Synthesis Summary Reports

Rozhnova et al. (Mar 12, 2021). Model-Based Evaluation of School- and Non-School-Related Measures to Control the COVID-19 Pandemic. Nature Communications. https://doi.org/10.1038/s41467-021-21899-6

• An age-structured SARS-CoV-2 transmission model fitted to data from the COVID-19 pandemic in the Netherlands suggested that if methods to reduce the effective reproduction number (R_e) of non-school-based contacts with non-school-based measures are exhausted or undesired and R_e is still near 1, school-based prevention measures may be beneficial, particularly among older students. The authors provide examples from summer and autumn 2020 as evidence that keeping schools closed after summer of 2020 likely would not have prevented the fall wave of infections, but closing schools in November 2020 may have reduced R_e.

Klein et al. (Feb 24, 2021). Stepping Back to School: A Step-by-Step Look at COVID Introduction, Spread, and Exportation. https://covid.idmod.org/data/Stepping_Back_to_School.pdf

• [Report, not peer-reviewed] Covasim, a model previously used to describe SARS-CoV-2 transmission among inter-personal contacts in King County, Washington predicted that the rate of introduction of SARS-CoV-2 into K-12 school classroom settings is proportional to the prevalence of SARS-CoV-2 in the community. The model is an agent-based model of contacts at home, school, work and in the community. According to the model, each 0.1% increase in community prevalence resulted in an increase in daily introduction rate by 3.1 per 100,000 population. In a classroom setting, if in-school transmissibility is low, potential outbreaks were predicted to be small, with additional countermeasures such as asymptomatic testing adding little value. If transmission is high, however, large outbreaks are possible with more transmissible variants or if interventions are insufficient. The model also predicted that the frequency of exports from schools to the broader community is dependent on the number of students infected in the schools. 

Kaiser et al. (Dec 2, 2020). Social Network-Based Strategies for Classroom Size Reduction Can Help Limit Outbreaks of SARS-CoV-2 in High Schools. A Simulation Study in Classrooms of Four European Countries. Pre-print downloaded Dec 3 from https://doi.org/10.1101/2020.11.30.20241166

• Pre-print, not peer reviewed] A simulation study of classroom based on longitudinal survey data collected from four European countries (n=507 classrooms, 12,291 students) found that while establishing student cohorts that minimize out-of-school contact between different cohorts would be most effective in preventing spread of SARS-CoV-2, cohorting by approximation of social networks also performed well. Network-based cohorting outperformed dividing classrooms by gender. For all cohorting strategies, schedules with alternating weeks of instruction were most effective.

Naimark et al. (Nov 21, 2020). The Potential Impact of School Closure Relative to Community-Based Non-Pharmaceutical Interventions on COVID-19 Cases in Ontario Canada. Pre-print downloaded Nov 23 from https://doi.org/10.1101/2020.11.18.20234351

• [Preprint, not peer-reviewed] A modeling study based on a scenario of one million individuals in Ontario, Canada predicted that school reopening would result in a small change in COVID-19 case numbers among students and teachers in a setting with community-based prevention measures. The model showed that the increase was driven mostly by acquisition in the community, and fewer than 5% of infections among students and teachers were acquired within schools. It also indicated that implementation of community-based prevention measures would reduce 39,355 COVID-19 incident cases by October 31, 2020, while school closure vs. reopening on September 15 would reduce 2,040 cases.

Bracis et al. (Nov 13, 2020). Widespread Testing, Case Isolation and Contact Tracing May Allow Safe School Reopening with Continued Moderate Physical Distancing: A Modeling Analysis of King County, WA Data. Infectious Disease Modelling. https://doi.org/10.1016/j.idm.2020.11.003

• Modeling based on King County, Washington State indicates that returning to a level of 75% of pre-COVID-19 physical interactions between May 15-July 15 was projected to result in 350 daily deaths by early September 2020. Maintaining less than 45% of pre-COVID-19 physical interactions was required to ensure low levels of daily infections and deaths. A combination of increased testing, isolation of symptomatic infections, and contact tracing permitted 60% of pre-COVID-19 physical interactions and allowed opening of schools with <15 daily deaths.

Klein et al. (Nov 5, 2020). Testing the waters: is it time to go back to school? Diagnostic screening as a COVID‐19 risk‐mitigation strategy for reopening schools in King County, WA. Institute for Disease Modeling. Downloaded Nov. 5 from https://covid.idmod.org/data/Testing_the_waters_time_to_go_back_to_school.pdf 

• [Pre-print, not peer-reviewed] Modeling of K-12 school reopening in King County, Washington found that if in-school countermeasures are observed, diagnostic screening either with PCR tests or rapid antigen tests may be of little benefit due to a higher rate of false positive tests in this low prevalence setting. Modeled in-school countermeasures included daily symptom screening, contact tracing, face masks, hand hygiene, improved ventilation, and physical distancing. Countermeasures could reduce the 3-month cumulative incidence to 2% or less for students, teachers, and staff. In this setting, school-based transmission was also found to be a limited driver of community spread, holding the effective reproduction number Re = 1 over 3 months.

Saad et al. (Nov 3, 2020). COVID-19 Active Surveillance Simulation Case Study – Health and Economic Impacts of Active Surveillance in a School Environment. Pre-print downloaded Nov 4 from https://doi.org/10.1101/2020.10.28.20221416

• A simulation study of a school environment concluded that daily testing can assist with maintenance of a low infection rate. The authors concluded that a reasonable daily test percentage (6%-10% with social distancing and mask wearing, or 8-10% without mitigation procedures) among the student population can achieve a low infection rate (≤10%).

Evidence of the effectiveness of bans on mass gathers, independent of the effect of other non-pharmaceutical interventions is relatively limited; however, there is some evidence that earlier implementation of bans on mass gatherings reduced mortality due to COVID-19. A number of well-documented “superspreading” events provides additional evidence for the potential effectiveness of mass gathering bans (Lemieux, Firestone).

Direct evidence for the effectiveness of school closures on community transmission of SARS-CoV-2 is inconclusive. In the presence of effective mitigation strategies, K-12 schools have not been shown to be important drivers of community transmission, at least in the context of relatively low community transmission (CDC). [For a more thorough examination of schools and COVID-19, refer to the COVID-19 the Synthesis Summary on COVID-19 and Schools. See section below on Mitigation Protocols – K-12 Schools].

Reopening of colleges and universities for in-person instruction has been linked to surges in cases in some communities (Pray, Vang). Much of the transmission on college and university campuses has been linked to social events and gatherings rather that in-person classes (Weil). [See section below on Mitigation Protocols – Colleges and Universities].

Experiments that simulate the dissemination of aerosols and droplets as well as computer models have shown that a broad range of mask and face covering types are at least partially effective at blocking the spread of aerosols and droplets from an infected individual (Akhtar). The greatest protection was from N95 respirators, with similar protection from a cloth mask over a medical procedure mask (double masking) (Brooks, Sharma).

Leung et al. (May 2020). Respiratory Virus Shedding in Exhaled Breath and Efficacy of Face Masks. Nature Medicine. https://doi.org/10.1038/s41591-020-0843-2

• Use of a surgical mask significantly reduced the proportion of droplets and aerosols with detectable virus among children and adults with confirmed seasonal coronavirus and seasonal influenza infection. Among 17 patients with seasonal coronavirus, virus was detected in 30% of droplets and 40% of aerosols among those randomized to not wear a surgical mask compared to 0% detection in both droplets and aerosols of those randomized to wear a surgical mask.
• Similar results were found for the effect of surgical masks worn by patients with seasonal influenza, but there was no effect of wearing a surgical mask among those with a rhinovirus infection.

Wide variation has been observed across different mask/face covering types in terms of control of aerosols and droplets, protection from infection, and filtration efficiency. N95 masks offer the highest level of protection, with similar performance for cloth masks combined with a medical procedure mask. Double layer cloth masks and higher thread-count cloth masks offer intermediate control of aerosols and droplets, while most single layer masks showed limited control (Guha, Clapp). It may be possible to improve the airtight fit of masks by using adhesive strips (Pan).

Face masks have been shown to prevent acquisition of SARS-CoV-2 when worn consistently and correctly by individuals who were taking care of patients with SARS-CoV-2. This protection has been observed both for healthcare workers (Akinbami, Schneider) and for caregivers of children with COVID-19 (Yun, Lee).

The implementation of mandates to wear facemasks or face coverings in public places when physical distancing is not possible have been associated with declines in the incidence COVID-19 cases (Guy). Most evidence for the effectiveness of mask mandates has come from ecological and time series analyses, which often complicate the identification of the effect of mask mandates separate from other non-pharmaceutical interventions (Rebeiro, Van Dyke, Adjodah). One analysis estimated that statewide mask mandates resulted in a 5.5 percentage point decrease in the COVID-19 hospitalization growth rate among adults aged 18–64 years after mandate implementation, compared to the growth rates during the 4 weeks preceding implementation of the mandate (Joo). Survey results indicate that higher levels of reported mask usage and physical distancing are associated with a greater likelihood that communities are able to gain control of SARS-CoV-2 transmission (Rader).

Arvelo et al. (Feb 12, 2021). COVID-19 Stats: Percentage of Middle and High School Students Aged 13–21 Years Attending In-Person Classes Who Reported Observing Fellow Students Wearing a Mask All the Time, by School Setting and Activity — United States, October 2020. MMWR. https://doi.org/10.15585/mmwr.mm7006a5 

• Among a sample of 3,953 middle and high school students participating in a Falcon-CDC Foundation cross-sectional web panel survey in October 2020, approximately 65% reported that fellow students wore a mask “all the time” in the classroom, hallways, and stairwells. Lower frequencies were reported for other indoor settings, including school buses (42%), restrooms (40%), and the cafeteria when not eating (36%). Reported mask use was lowest in outdoor settings (extracurricular activities 28%, outside school property 25%).

Basch et al. (Feb 2, 2021). Promoting Mask Use on TikTok: A Descriptive Study on Unconventional Approach to Public Health Education. JMIR Public Health and Surveillance. https://doi.org/10.2196/26392 

• Videos promoting mask use posted on the social media platform TikTok with the hashtag #WearAMask (n=100) received almost 10 times as many cumulative views as videos by the World Health Organization (WHO) to promote mask use (n=32). Most of the #WearAMask videos used humor and dance to garner almost 500 million views. In contrast, the WHO videos, of which 3 included humor and none included dance, only garnered over 57 million views.

Barceló and Sheen. (Dec 1, 2020). Voluntary Adoption of Social Welfare-Enhancing Behavior: Mask-Wearing in Spain during the COVID-19 Outbreak. PloS One. https://doi.org/10.1371/journal.pone.0242764

• A nationally representative survey of 4000 citizens in Spain during early stages of the COVID-19 pandemic reported that 49% of respondents wore protective masks either occasionally or very frequently, 10% rarely wore a mask, and 41% never wore a mask. People who were young, had higher educational attainment, reported a lower concern about infection, and with an introverted personality were less likely to wear a mask.

Hoeben et al. (Mar 15, 2021). Social Distancing Compliance: A Video Observational Analysis. PLOS ONE. https://doi.org/10.1371/journal.pone.0248221

• Closed Circuit Television (CCTV) footage in inner-city Amsterdam, Netherlands showed short-lived adherence to physical distancing measures following implementation of “lockdown” policies. From February to May 2020, the observed number of physical distancing violations (less than 1.5 meters) decreased following announcements of physical distancing measures and full lockdown on March 23rd, but then increased onwards from April 2 until the end of the observation period.

Czeisler et al. (Mar 15, 2021). Early Public Adherence with and Support for Stay-at-Home COVID-19 Mitigation Strategies despite Adverse Life Impact: A Transnational Cross-Sectional Survey Study in the United States and Australia. BMC Public Health. https://doi.org/10.1186/s12889-021-10410-x

• Self-reported adherence to COVID-19 mitigation policies was high in both highly- and minimally-affected regions in the US around the time of the first wave in April 2020, according to representative cross-sectional surveys (n=5,573) administered to adults residing in throughout the US, in New York City and Los Angeles, and Australia. 82% reported adherence to recommended quarantine and stay-at-home policies, and 90% supported government-imposed measures.

de Vries et al. (Jan 25, 2021). Dynamic Public Perceptions of the Coronavirus Disease Crisis, the Netherlands, 2020. Emerging Infectious Diseases. https://pubmed.ncbi.nlm.nih.gov/33493429

• Monitoring of public perceptions during the first 3 months of the COVID-19 pandemic in the Netherlands found that respondents believed the risks associated with COVID-19 to be considerable, were positive about mitigation measures, trusted in information and response from authorities, and reported widespread adoption of protective measures. Differences in perception were mostly driven by factors such as respondents’ age and health condition. Respondents consisted of roughly 11,000 residents participating across 6 repeat surveys, with an oversampling of persons aged >65 years.

McAloon et al. (Jan 25, 2021). Numbers of Close Contacts of Individuals Infected with SARS-CoV-2 and Their Association with Government Intervention Strategies. Pre-print downloaded Jan 26 from https://doi.org/10.1101/2021.01.20.21250109

• [Pre-print, not peer-reviewed] Analysis of more than 140,000 contacts of over 40,000 SARS-CoV-2 positive cases in Ireland from May to December 2020 showed that the number of contacts per case varied across specific populations and trended with implementation of government interventions. The number of contacts per case was highest among those aged 18-24 years and lowest among those >65 years. The number of contacts per case increased after stay-at-home orders were lifted in May from a minimum of 2 to a peak of 6, then fell back to 2.6 at the beginning of Level 5 restrictions in October.

Crane et al. (Jan 22, 2021). Change in Reported Adherence to Nonpharmaceutical Interventions During the COVID-19 Pandemic, April-November 2020. JAMA. https://doi.org/10.1001/jama.2021.0286

• An analysis of the Coronavirus Tracking Survey completed between April 1 and November 24, 2020 found that the adherence index (range 0 [low] to 100 [high]) to non-pharmaceutical interventions decreased substantially from 70 in April to the high 50’s in June, before rising back to 60 by late November. All US Census regions experienced significant decreases in the NPI adherence index during this time. Protective behaviors that had the largest decreases in adherence were staying at home, except for essential activities or exercise, (80% to 41%), having no close contact with non–household members (64% to 38%), not having visitors (80% to 58%), and avoiding eating at restaurants (87% to 66%). Reported mask wearing showed a significant increase among participants from 39% to 89%.

Ipsen et al. (Jan 18, 2021). A Cross-Sectional Analysis of Trust of Information and COVID-19 Preventative Practices among People with Disabilities. Disability and Health Journal. https://doi.org/10.1016/j.dhjo.2021.101062

• Survey participants with disabilities who live outside of metropolitan areas had the lowest COVID-19 information trust ratings and reported significantly less trust in most information sources when compared to people with disabilities in either metropolitan or micropolitan counties. Increased compliance with CDC guidelines was associated with being over 65, identifying as female, and higher general trust scores. Decreased compliance with CDC guidelines was associated with being nonwhite, living in a nonmetropolitan area, higher trust scores in President Trump, and having a communication disability.

Bateman et al. (Jan 21, 2021). Confronting COVID-19 in under-Resourced, African American Neighborhoods: A Qualitative Study Examining Community Member and Stakeholders’ Perceptions. Ethnicity & Health. https://doi.org/10.1080/13557858.2021.1873250

• Qualitative research conducted in under-resourced communities in Alabama found that Black community members highlighted concerns about contracting COVID-19 and noted apathy, difficulty with social distancing, lack of information, mixed messages from authority figures, and lack of PPE as barriers to prevention. Facilitators to coping with the pandemic included religious faith, increased physical activity, and a sense of hope; barriers included insecurity, mental health issues, isolation, economic hardships, lack of health care access, and issues with virtual schooling and church services, which were exacerbated by Internet connectivity problems. Facilitators to testing included incentives, clear information from trusted sources, convenient testing locations, and free tests, while misunderstanding, fear, mistrust, testing restrictions, and location of testing sites were identified as barriers.

Anderson and Stockman. (Dec 29, 2020). Staying Home, Distancing, and Face Masks: COVID-19 Prevention among U.S. Women in The COPE Study. International Journal of Environmental Research and Public Health. https://doi.org/10.3390/ijerph18010180

• Findings from the cross-sectional COPE Study (n=491) of women in the United States conducted from May to June 2020 suggest that women’s prevention behaviors for SARS-CoV-2 transmission are influenced by multilevel factors. Women who lived in urban environments, had minimal formal education, or had a household annual income of USD 30,000–50,000 were less likely to practice prevention behaviors. Cultural context was noted as a potentially important factor in the decision-making process.

Hutchins et al. (Oct 27, 2020). COVID-19 Mitigation Behaviors by Age Group — United States, April–June 2020. MMWR. https://doi.org/10.15585/mmwr.mm6943e4 

• A nationally representative survey (n=6,475) conducted in three waves from April to June 2020 found that self-reported mask wearing increased across survey waves, while handwashing, physical distancing, and cancelling social activities decreased. Avoiding some or all restaurants did not change significantly. While >40% of respondents reported following all recommended behaviors across all waves, engagement was lowest among adults aged 18-29 years and highest among those aged >60 years.

While there is clear evidence for the potential for widespread transmission of SARS-CoV-2 in a school environment, there is also direct and indirect evidence that the development of and adherence to protocols to minimize the risk of transmission through the use of face masks, physical distancing, and other control measure as well as identifying cases, isolating infected individuals, quarantining close contacts, and maintaining cohorts or capsules with limited mixing between groups can substantially limit the spread of SARS-CoV-2 in the context of group settings with school-age children. The role of fomite transmission remains incompletely understood, particularly in the context of high levels of mask usage (Kraay).

The CDC has revised its guidelines regarding physical distancing in classrooms, recommending a change from ≥6 foot to  ≥3 foot spacing in response to evidence the schools with a 3 foot spacing policy did not have higher incidence of COVID-19 compared to schools with a 6 foot spacing policy in the context of universal masking and other mitigation measures in place (van den Berg).

There is very little evidence, both in the context of low and high community transmission, that schools have been a driver of transmission (Leidman, Monod, Mensah, Doyle, Ladhani). In England (Mensah) and Florida (Doyle), incidence of COVID-19 in school children mirrors the incidence in the general population with a lag indicating that community transmission was the driver of infections in children. Another study from England found adults (≤65 years old) had a higher risk of SARS-CoV-2 infection if they lived in a household with school-age children during the second wave of the pandemic, although the role of school-based transmission was not clear (Forbes). During a period when schools had not yet re-opened, relaxation of mobility restrictions and re-opening other businesses and activities was associated with considerable increases in the prevalence of COVID-19 among adolescents and youth, indicating that exposures outside of the classroom are like more relevant to transmission in this age group than school-based transmission (Rumain).

Secondary transmission of SARS-CoV-2 from an infected student to their close contacts has been low, estimated at 2% of 102 close contacts identified in investigations of cases that occurred in K-12 schools (n=22) in Springfield and St. Louis County, Missouri (Dawson) and a secondary attack rate of 0.5% in New York City (Varma).

A small number of countries in regions with some level of community transmission of SARS-CoV-2 never imposed school closures. Sweden is notable among countries that did not close all schools, although Sweden did close schools for secondary grade students between March 18 and June 4, 2020 (Vogel). The incidence of severe COVID-19 was low among school-age children in Sweden and the risk among schoolteachers was similar to other occupations (Ludvigsson) Starting in late April and May 2020, many countries around the world started re-opening schools, many of which also sustained limits on other mobility and closures of many businesses after schools were re-opened. Since the initial re-opening, which often occurred for subsets of students or with modified schedules, schools have fully reopened for all students in many settings. While there have been examples of large-scale school closures in response to cases arising in schools soon after re-opening, particularly when school re-opening coincided with widespread relaxation of mobility restrictions and business closures (Israel, parts of the United States), many countries have been able to keep the large majority of schools open, even as cases of COVID-19 have increased in the community (Germany, France, Norway, Belgium, Scotland, South Korea). 

According to a landscape analysis, most of the largest public and private institutions of higher education provided at least some in-person teaching during the Fall 2020 semester, most of which offered a hybrid reopening structure (Freeman). Outbreaks of SARS-CoV-2 have been observed on multiple college and university campuses, with evidence that campus outbreaks have driven surges in surrounding communities in some cases. Much of the transmission linked to colleges and universities has been linked to social and extracurricular activities rather than in-person instruction (Vang, Weil). Implementation of mitigation protocols and testing programs has been shown to result in control of outbreaks (Fox, O’Donnell).

Self, J et al. (Mar 18, 2021). Shelter Characteristics, Infection Prevention Practices, and Universal Testing for SARS-CoV-2 at Homeless Shelters in 7 US Urban Areas. American Journal of Public Health. https://doi.org/10.2105/AJPH.2021.306198

• Findings from SARS-CoV-2 testing offered to clients and staff at 63 homeless shelters, irrespective of symptoms, found lower prevalence of infection at shelters that implemented head-to-toe sleeping and that excluded symptomatic staff from working. Shelters with medical services available were less likely to have very high infection prevalence (defined as >10%).

Chin et al. (Mar 8, 2021). Covid-19 in the California State Prison System An Observational Study of Decarceration Ongoing Risks and Risk Factors. Pre-print downloaded Mar 9 from https://doi.org/10.1101/2021.03.04.21252942

• [Pre-print, not peer-reviewed] In 9 California prisons that experienced major COVID-19 outbreaks, risk factors for SARS-CoV-2 infection included living in a dormitory vs. in a cell (2.5-fold risk) and living in a room with residents who participated in out-of-room labor vs. other rooms (1.6-fold).  By the end of the study, 18% had high COVID-19 risk scores, among whom nearly 40% lived in dormitory settings, and 15% lived in rooms with 10 or more occupants. The observational study also found that the incarcerated population in the state decreased by 19% between March to October 2020.

Marcus et al. (Feb 25, 2021). Risk Factors Associated With COVID-19 Transmission Among US Air Force Trainees in a Congregant Setting. JAMA Network Open. https://doi.org/10.1001/jamanetworkopen.2021.0202

• A higher number of symptoms and higher viral loads were associated with subsequent clusters of SARS-CoV-2 cases among cohorts of US Air Force basic trainees. Among 10,613 US Air Force basic trainees, of whom 3% (403) received a diagnosis of COVID-19 during the study period, higher numbers of symptoms and higher viral loads (lower cycle threshold (Ct) values) were associated with subsequent development of clusters of individuals with COVID-19 infection. The authors suggest that Ct values may be useful in assessing risk of ongoing transmission in specific cohorts. 
• Although individual cases of COVID-19 occurred in almost half of all training cohorts, only 11% of cohorts had an initial individual case that resulted in a cluster of 5 or more cases, a success that the authors attributed to effective non-pharmaceutical interventions among the trainees. 

Kiran et al. (Jan 30, 2021). Factors Associated with SARS-CoV-2 Positivity in 20 Homeless Shelters in Toronto, Canada, from April to July 2020: A Repeated Cross-Sectional Study. CMAJ Open. https://doi.org/10.9778/cmajo.20200253

• Among 872 residents of homeless shelters in Toronto, Canada across 20 shelter locations, 504 unique individuals had a SARS-CoV-2 tests performed in outbreak settings (April 1 to July 31, 2020), of which 69 (14%) were positive. There was no association between SARS-CoV-2 positivity and medical history or symptoms. Those who tested positive for SARS-CoV-2 were significantly less likely than those who tested negative to have visited another shelter in the last 14 days (0% vs. 18%). The authors suggest that their findings support testing asymptomatic individuals in shelter settings when a positive case has been identified at the same shelter.

Shumsky et al. (Mar 16, 2021). Retail Store Customer Flow and COVID-19 Transmission. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.2019225118

• A mathematical model analyzing retail customer flow and SARS-CoV-2 transmission found that then restricting customers to one-way movement could reduce transmission rates to less than one-third of the rate with two-way movement, if all customers comply and transmission occurs primarily through close contact. The model was calibrated using published epidemiologic data and predicted that for a medium-sized retail store in an area with relatively high COVID-19 prevalence, the transmission rate (via direct and wake exposure) would be 0.33 infections per day without complete one-way flow compliance. 

Nachman et al. (Mar 12, 2021). Day Camp in the Time of COVID-19: What Went Right? Pre-print downloaded Mar 15 from https://doi.org/10.1101/2021.03.11.21253309

• [Pre-print, not peer-reviewed] A survey of summer day camp directors (n = 23) in the metropolitan New York area conducted in September 2020 regarding their camps’ COVID-19 policies during the summer of 2020 found that common infection prevention policies included COVID-19 screening at entry, placing camp attendees in cohorts, maximizing outdoor activities, mandating mask use when indoors, and frequent hand sanitizing. Out of 8,480 children and 3,698 staff, six staff and one camper tested positive for COVID-19. There was no secondary transmission within camps, and infection rates were lower in camps than in the counties where the camps were located. 

Watson et al. (Mar 3, 2021). COVID-19 in Youth Soccer During Summer 2020. Journal of Athletic Training. https://doi.org/10.4085/610-20

• US youth soccer clubs reported a relatively low incidence of COVID-19 among their players in a retrospective cohort study of 119 US youth soccer clubs representing 91,007 players with a median duration of 73 days since restarting group activities. Soccer players reported a 49% lower incidence than children nationally over the same time period (254 vs 477 cases per 100,000). After adjusting for local COVID-19 incidence, there was no relationship between club COVID-19 incidence and phase of return. Clubs reported using a median of 8 COVID-19 risk reduction strategies.

Lendacki et al. (Feb 24, 2021). COVID-19 Outbreak Among Attendees of an Exercise Facility — Chicago, Illinois, August–September 2020. MMWR. https://doi.org/10.15585/mmwr.mm7009e2

• A large outbreak of COVID-19 occurred among attendees of indoor high-intensity classes at a Chicago exercise facility in August, 2020, with 55 cases identified among 81 attendees (68% attack rate). All classes were held at reduced capacity (<25%), temperature checks were required upon entry, and participants were required to space mats at least 6 feet apart. 22 (40%) people with COVID-19 attended classes on or after the day symptoms began, and most attendees (76%) wore masks infrequently, including people with (84%) and without COVID-19 (60%). Overall, 43 (78%) of attendees with COVID-19 attended more than one class while they were potentially infectious.

Groves et al. (Feb 24, 2021). Community Transmission of SARS-CoV-2 at Three Fitness Facilities — Hawaii, June–July 2020. MMWR. https://doi.org/10.15585/mmwr.mm7009e1

• An outbreak of COVID-19 cases occurred that was linked to a fitness instructor resulting in cases at 3 fitness facilities, with the highest attack rate (95%) occurring in classes that were taught <1 day before the onset of symptoms in the instructor. Twenty-one cases of COVID-19 were linked to an index case fitness instructor in Hawaii in July, 2020, including a case in another fitness instructor. The aggregate attack rates in classes taught by both instructors <1 day, 1 to <2 days, and ≥2 days before symptom onset were 95% (20 of 21), 13% (one of eight), and 0% (zero of 33), respectively. Among the 21 secondary cases, 20 (95%) had symptomatic illness, two (10%) of whom were hospitalized. At the time of the outbreak, mask use was not required in the facilities. 

Sami et al. (Feb 24, 2021). SARS-CoV-2 Infection and Mitigation Efforts among Office Workers, Washington, DC, USA. Emerging Infectious Diseases. https://doi.org/10.3201/eid2702.204529

• Two SARS-CoV-2 outbreaks in April, 2020 were identified among office workers in Washington, DC. The study identified two factors potentially associated with SARS-CoV-2 infection and transmission in the workplace: a significantly higher percentage of seropositive participants lived with someone who had a confirmed positive test result (13%) than those who were seronegative (1%), and more (60% vs. 32%) seropositive participants traveled by taxi after the cancellation of nonessential gatherings on March 11, 2020. There was no significant difference in workplace mitigation activities between seropositive and seronegative participants, including using a face covering most of the time or always, maintaining a distance of >6 feet, and washing hands or using hand sanitizer >5 times per day.

Billock et al. (Feb 19, 2021). Required and Voluntary Occupational Use of Hazard Controls for COVID-19 Prevention in Non-Health Care Workplaces – United States, June 2020. MMWR. https://doi.org/10.15585/mmwr.mm7007a5

• 46% of non-remote, non–health care workers used hazard controls to prevent COVID (e.g., physical barriers, masks, and other personal protective equipment). Although 56% of workers surveyed reported required use at work, higher-income workers were more likely to report required use and to use hazard controls than were lower-income workers. Among workers not using hazard controls, 8% were prohibited from using them, 15% could not obtain them, and 77% did not believe they were needed.

Leidman et al. (Oct 23, 2020). Adoption of Strategies to Mitigate Transmission of COVID-19 During a Statewide Primary Election — Delaware, September 2020. MMWR. https://doi.org/10.15585/mmwr.mm6943e2

• Survey responses from primary election poll workers in Delaware indicated that SARS-CoV-2 mitigation measures at polling places generally aligned with CDC guidelines and were widely adopted and feasible, but there were some gaps in infection prevention control efforts. Most poll workers surveyed had good knowledge about SARS-CoV-2 transmission and 80% had received COVID-19 mitigation training. However, masks were not always worn correctly (covering both nose and mouth), and 72% of respondents reported being within 6 feet of more than 100 people on election day.

Ronchi et al. (Dec 7, 2020). Evaluation of Rooming-in Practice for Neonates Born to Mothers With Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Italy. JAMA Pediatrics. https://jamanetwork.com/journals/jamapediatrics/fullarticle/2773311

• It may be possible to effectively mitigate the risk of mother-to-infant transmission of SARS-CoV-2 infection, based on findings from a multi-cohort study of mother-infant dyads (n=62 neonates, 61 mothers) in Italy that found no positive results among neonates 24 hours after birth despite a 95% breastfeeding rate. Infected mothers observed contact precautions such as handwashing and mask use while breastfeeding. At follow-up until age 3 weeks, only 1 infant was diagnosed as having SARS-CoV-2 infection.

McIlveen et al. (Feb 5, 2021). Reduction in Oregon’s Medication Dosing Visits After the SARS-CoV-2 Relaxation of Restrictions on Take-Home Medication. Journal of Addiction Medicine. https://pubmed.ncbi.nlm.nih.gov/33560697

• Opioid treatment programs in Oregon saw a reduction in medication dosing visits and an increase in take-home doses dispensed following a relaxation of restrictions on take-home medication dosing that were intended to slow the spread of SARS-CoV-2. During the pre-SARS-CoV-2 period (February and early March 2020), patients made a mean of 16 visits per month to opioid treatment programs, with 6 take-home doses per patient per month. Following the policy change, medication visits declined 33% and take-home medication increased 97% with a mean of 10 visits per patient and a mean of 11 take-homes per patient.

Courtney et al. (Feb 4, 2021). Decreases in Young Children Who Received Blood Lead Level Testing During COVID-19 – 34 Jurisdictions, January-May 2020. MMWR. https://doi.org/10.15585/mmwr.mm7005a2

• 34% fewer US children aged <6 years had blood lead level (BLL) testing during January–May 2020 when compared to January–May 2019, according to data from 34 state and local health departments. The authors estimate that reduced testing due to the COVID-19 pandemic has led to missed identification of 9,603 children with elevated BLLs.

Holland et al. (Feb 3, 2021). Trends in US Emergency Department Visits for Mental Health, Overdose, and Violence Outcomes Before and During the COVID-19 Pandemic. JAMA Psychiatry. https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2775991

• The median proportion of US emergency department (ED) visits that were related to mental health conditions, suicide attempts, all drug and opioid overdoses, and suspected child abuse and neglect (SCAN) were significantly higher from mid-March to October 2020 compared to the same period in 2019, based on a cross-sectional study of nearly 190 million visits using data from the CDC’s National Syndromic Surveillance Program. In contrast, the proportion of visits due to intimate partner violence (IPV) was similar in the 2019 and 2020 time periods. Median visit counts for suicide attempts, all drug and opioid overdoses, IPV, and SCAN were significantly higher in the 2020 than 2019 time periods.

Partridge et al. (Jan 25, 2021). Evaluation of Seasonal Respiratory Virus Activity Before and After the Statewide COVID-19 Shelter-in-Place Order in Northern California. JAMA Network Open. https://doi.org/10.1001/jamanetworkopen.2020.35281

• Infection rates for influenza and rhinovirus or enterovirus were significantly lower during March 25 to July 31, 2020 compared to the same time period during the past 5 years, according to a cohort study in California that included over 45,000 tests for the viral respiratory infections. This significant drop in infection rates coincided with implementation of shelter-in-place orders on March 19, 2020. Influenza infection rates decreased by 93%, while rhinovirus or enterovirus infection rates decreased by 81%. In contrast, infection rates for the portions of the 2020 respiratory virus season prior to March 25th were similar to rates for the same period over the past 5 years (30.4 vs 33.7 positive results per 100 tests).

Chang and Levy. (Jan 19, 2021). High Prevalence of Elder Abuse During the COVID-19 Pandemic: Risk and Resilience Factors. The American Journal of Geriatric Psychiatry. https://doi.org/10.1016/j.jagp.2021.01.007

• A survey of older adults (n=897) sheltering in place during the pandemic found the prevalence of self-reported elder abuse was 21.3%, an 83% increase from the pre-pandemic period. Increased risk of elder abuse was associated with greater pandemic-related financial hardship, while reduced risk was associated with having a strong sense of community (OR = 0.89) and adherence to distancing measures (OR = 0.94).

Freeman et al. (Jan 1, 2021). Effectiveness of Physical Distancing: Staying 6 Feet Over to Put Respiratory Viruses 6 Feet Under. Mayo Clinic Proceedings. https://doi.org/10.1016/j.mayocp.2020.10.040

• Results from an analysis of 13,324 nasopharyngeal swabs collected at a single hospital in Arizona between January 1, 2017, and July 31, 2020, found a significant reduction in the detection of respiratory viruses other than SARS-CoV-2, coinciding with the implementation of distancing and masking policies during the COVID-19 pandemic. The average monthly positivity rate for the months between April and July declined from 25% for 2017–2019 to 2% in the same period of 2020. However, it is not clear what proportions of the observed declines in testing and positivity were due to non-pharmaceutical interventions, since the COVID-19 pandemic may also be causing reluctance to seek medical care.

Altschul et al. (Dec 20, 2020). Face Covering Adherence Is Positively Associated with Better Mental Health and Wellbeing a Longitudinal Analysis of the CovidLife Surveys. Pre-print downloaded Dec 21 from https://www.medrxiv.org/content/10.1101/2020.12.18.20248477v1

• [Pre-print, not peer-reviewed] A longitudinal UK-wide survey found that individuals who wore face coverings “most of the time” or “always” had better mental health and wellbeing than those who did not, even after controlling for behavioral, social, and psychological factors. The odds of feeling anxious were 58% lower among individuals who “always” adhered to guidance on wearing face coverings, and the odds of having depressive symptoms were 25% lower among individuals who “always” adhered to the guidance.

Trenholme et al. (Dec 2, 2021). COVID-19 and Infant Hospitalizations for Seasonal Respiratory Virus Infections, New Zealand, 2020. Emerging Infectious Diseases. https://doi.org/10.3201/eid2702.204041

• A pediatric hospital in South Auckland, New Zealand observed a dramatic decrease in cases of influenza and respiratory syncytial virus after COVID-19 lockdown measures were implemented in March 2020, compared to prior seasons. Additionally, case reductions were sustained after gradual reopening beginning in April 2020. While annual hospitalizations for lower respiratory tract infections ranged from 1,486 to 2,046 during 2015-2019, only 268 admissions were reported in 2020, despite similar rates of clinician-directed PCR tests.

Zhang et al. (Nov 30, 2020). Rapid Disappearance of Influenza Following the Implementation of COVID-19 Mitigation Measures in Hamilton Ontario. Pre-print downloaded Dec 1 from https://doi.org/10.1101/2020.11.27.20240036

• [Pre-print, not peer reviewed] Following population-wide implementation of COVID-19 interventions in Hamilton, Ontario, the proportion of samples that tested positive for influenza A and B dropped rapidly to 0% by the week of March 15-21. During the 2010-2019 influenza seasons, the proportion of positive tests reached 0% on a median of the week of May 30-June 6. Data were collected from all nasopharyngeal swab specimens (n=57,503) submitted for routine respiratory virus testing between January 2010 and June 2020.

Sherman et al. (Nov 8, 2020). The Effect of SARS-CoV-2 Mitigation Strategies on Seasonal Respiratory Viruses: A Tale of Two Large Metropolitan Centers in the United States. Clinical Infectious Diseases. https://doi.org/10.1093/cid/ciaa1704 

• Public health measures implemented to reduce SARS-CoV-2 transmission may have reduced the transmission of other seasonal respiratory viruses. In a retrospective review of medical records from health systems in Atlanta and Boston, average reproductive number (R_t) was found to remain above 1 for much longer in the past 5 seasons for influenza A, influenza B, and respiratory syncytial virus (RSV) compared to the September 2019-May 2020 season, which coincided with the COVID-19 pandemic. Declines in R_t in both locations in 2020 seemed to coincide with implementation of non-pharmaceutical interventions.

Type: mRNA

Doses: 2 doses 28 days apart

Handling requirements: (per EUA package insert) Store -25 °C to -15 °C. Can be refrigerated up to 30 days at 2 °C to 8 °C prior to use (cannot refreeze).

Level of evidence for efficacy: Phase III placebo-controlled efficacy trial

Regulatory status:

US: Approved for use under an Emergency Use Authorization

• Results from a phase 3 randomized, observer-blinded, placebo-controlled trial of the Moderna SARS-CoV-2 vaccine candidate (mRNA-1273) indicated that the vaccine showed 94.1% efficacy at preventing COVID-19, including severe disease. 30,420 volunteers were enrolled (15,210 placebo, 15,210 vaccine).
• Efficacy was similar across key secondary analyses, including in participants who had evidence of SARS-CoV-2 infection at baseline and analyses in participants 65 years of age or older.
• Serious adverse events were rare, and the incidence was similar to placebo.
• Reactogenicity after one dose was less than that observed for the recombinant adjuvanted herpes zoster (shingles) vaccine and after the second mRNA-1273 dose was similar to that of the herpes zoster vaccine (Cunningham).

Primary Endpoints by arm

Definition of primary endpoints

PCR+ with approved test PLUS:

Type: mRNA

Doses: 2 doses, 21 days apart

Handling requirements: -80 °C to -60 °C storage. Once thawed, can store undiluted vials for up to five days (120 hours) at 2C-8C.

Level of evidence for efficacy: Phase III placebo-controlled efficacy trial

Regulatory status:

US: Approved for use under an Emergency Use Authorization

• Results of the phase 3 double-blind, randomized, placebo-controlled trial for the Pfizer-BioNTech mRNA vaccine BNT162b2 (n=21,720 in vaccine group, and 21,728 in placebo group) showed a vaccine efficacy of 95% (95% CI 90.3-97.6), with 8 cases of COVID-19 (1 severe case) in the vaccine group and 162 cases (9 severe cases) in the placebo group.
• Efficacy was similar across subgroups defined by age, sex, race, ethnicity, body-mass index, and presence of co-existing conditions.
• Mild-to-moderate reactogenicity was commonly observed and increased with the second dose. Severe fatigue was observed in approximately 4% of BNT162b2 recipients, which is lower than observed in recipients of the Shingrix vaccine (another approved viral vaccine for older adults).
• Few participants in either group had severe or serious adverse events, and the 6 deaths (2 in vaccine group, 4 in placebo group) were determined by investigators not to be related to the vaccine or placebo by investigators.

Primary Endpoints by arm

Definition of primary endpoints

PCR+ with approved test PLUS:

Type: Replication incompetent adenovirus (Adenovirus 26)

Doses: 1 dose

Handling requirements: Stored at 2 °C to 8 °C.

Level of evidence for efficacy: Phase III placebo-controlled efficacy trial

Regulatory status:

US: Approved for use under an Emergency Use Authorization

• Vaccine efficacy against laboratory-confirmed moderate to severe/critical COVID-19 across all geographic areas in which the trial was conducted (including South Africa where the B.1.351 variant was circulating at the time) was 66.9% when considering cases occurring at least 14 days after the single-dose vaccination and 66.1% considering cases occurring at least 28 days after vaccination. Efficacy against severe/critical COVID-19 occurring at least 14 days and at least 28 days after vaccination was 76.7% and 85.4%, respectively.

Primary Endpoints (COVID-19 Onset at least 14 Days after vaccination) by arm

Primary Endpoints (COVID-19 Onset at least 28 Days after vaccination) by arm

Definition of primary endpoints

PCR+ with approved test PLUS:

Type: Recombinant protein

Doses: 2 doses, 21 days apart

Handling requirements: Store at 2 °C to 8 °C.

Regulatory status:

US: Anticipated EUA application is expected soon on the basis of US trial results

• Based on a press release from Novavax, preliminary results for phase 2/3 trials for the recombinant protein-based COVID-19 vaccine NVX-CoV2373 made by Novavax showed up to 3% efficacy in the UK cohort (n= >15,000), where 56 participants in the placebo group developed COVID-19 vs 6 in the vaccine group (Novavax).
• Of note, the 1.1.7 variant (first described in the UK) was observed in 32 of the COVID-19 cases, yielding an estimate of 85.6% efficacy against the variant.
• Preliminary results from the South Africa cohort (n= >4,400) showed efficacy of 60% in the HIV-negative study population vs. 49.4% in the overall study population, with 29 COVID-19 cases observed in the placebo group vs. 15 in the vaccine group.
• In the South Africa cohort, among 27 of the 44 cases with sequence data, mutations consistent with the B.1.351 variant (first described in South Africa) were detected in 25 (93%).
• Approximately 1/3 of patients in the South Africa cohort (but not included in the preliminary results) were SARS-CoV-2 seropositive at baseline, indicating prior SARS-CoV-2 infection.

Primary Endpoints by arm (Note: US trial is ongoing)

Definition of primary endpoints

Type: Chimpanzee adenoviral vector

Doses: 2 doses, 28 days apart

Handling requirements: Store at 2°C to 8 °C

Regulatory status:

US: Undergoing licensure trial in US (separate from trials that lead to licensure in UK)

The Oxford-AstraZeneca chimpanzee adenoviral vector vaccine (ChAdOx1 NCoV-19 Vaccine, AZD1222) has a more complex regulatory path and is currently undergoing a trial intended to facilitate licensure in the US. The results of that trial are not yet available. The trials supporting licensure in the UK are listed below. Additional complexity is added by different dosing intervals and doses used during each clinical trial conducted to date.

UK and Brazil Cohorts:

• An interim analysis of two of the four ongoing phase 2/3 trials for the Oxford–AstraZeneca chimpanzee adenovirus vectored vaccine ChAdOx1 nCoV-19 (n=7,548 in UK trial, n=4,088 in Brazil trial) showed a vaccine efficacy of 62.1% (95%CI 41.0-75.7%) among participants who received the planned two standard doses (Voysey).
• A smaller number of participants (n=1367 in the vaccine group and 1374 in the placebo group) erroneously received a low initial dose followed by a standard second dose. The observed vaccine efficacy for the low-dose/standard dose combination was 90.0% (95% CI 67.4-97.0) (3 of 1,367 in the vaccine group vs 30 of 1,374 in the placebo group) (Voysey).
• The overall vaccine efficacy against symptomatic COVID-19 was 70.4% (95.8% CI 54.8-80.6%) (Voysey).
• The majority of participants included in this interim analysis were aged 18-55 (88%), white (83%), and female (61%).
• The efficacy the ChAdOx1 nCoV-19 vaccine against the B.1.1.7 variant of SARS-CoV-2 was similar to the efficacy against parent lineages, with 74% efficacy against B.1.1.7 compared to 84% efficacy against non- B.1.1.7 lineages (Emary). Vaccine-induced antibodies had an approximately nine-fold reduction in neutralization activity against the B.1.1.7 variant compared to a canonical non-B.1.1.7 lineage in a live-virus neutralization assay.
• Among those vaccinated with ChAdOx1 who subsequently became infected with SARS-CoV-2, both the duration of shedding and viral load was lower than among control participants (Emary).
• Exploratory analysis of interim data from trials of the Oxford-AstraZeneca vaccine suggested that lengthening the interval between vaccination doses was associated with increases in clinical efficacy (Voysey).
• In a subset of participants who elected not to receive the second dose, the efficacy of a single-dose was 76% and protection did not decline during the 3-month period following the initial vaccination (Voysey).
• Participants in the study also received weekly swabs to look for detectable nucleic acid in the absence of symptoms. Overall reduction in PCR+ samples was 54% (45%-62%), suggesting a potential for reduced transmissibility (Voysey).

Note: the South African study was stopped due to the apparent lack of activity against the mild disease caused by the B.1.3.5 variant. Data from this decision – including efficacy against severe disease – have not been made public to date.

Primary Endpoints by arm

Type: Adenovirus viral vector

Doses: 2 doses, 21 days apart. Note: there are actually two adenoviruses used (first dose is recombinant adenovirus 26 followed by recombinant adenovirus 5).

Handling requirements: Stored at 2 °C to 8 °C

Logunov et al. (Feb 2, 2021). Articles Safety and Efficacy of an RAd26 and RAd5 Vector-Based Heterologous Prime-Boost COVID-19 Vaccine: An Interim Analysis of a Randomised Controlled Phase 3 Trial in Russia. The Lancet. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00234-8/fulltext 

• Interim analysis of the randomized, double-blind, placebo-controlled phase 3 trial for the recombinant adenovirus (rAd)-based vaccine Gam-COVID-Vac (Sputnik V) (n=19,866) showed an efficacy of 91.6% (CI: 85.6%-95.2%) by 21 days after the first dose of vaccine (the day of dose 2). 16 of 14,964 (0.1%) people in the vaccine group developed COVID-19 compared to 62 of 4,902 (1.3%) people in the placebo group. Participants were required to be IgG/IgM negative at baseline for enrollment. Rates of disease onset were similar for the vaccine and placebo groups until about 16 to 18 days after the first dose.
• The observed vaccine efficacy was >87% in all age and sex subgroups (60% male), and 91.8% in participants aged >60 years (11% of participants). 98.5% of participants were white, and the entire study was conducted in 25 hospitals and polyclinics in Moscow, Russia. 94% of reported adverse events were grade 1, with 0.3% and 0.4% of vaccine and placebo group experiencing serious adverse events, respectively.

Definition of primary endpoints

Type: inactivated

Doses: 2 doses, 14 days apart

Handling requirements: Stored at 2 °C to 8 °C

Note neither the underlying protocol nor the underlying data were made publicly available at present.

Press release: “As of December 16, 2020, there were 12,396 health workers over 18 years old enrolled. A total of 253 positive cases were collected during the observation period. After 14 days following vaccination with 2 doses of vaccine following a 0, 14 day schedule, the efficacy rate against diseases caused by COVID-19 was 50.65% for all cases, 83.70% for cases requiring medical treatment, and 100.00% for hospitalized, severe, and fatal cases.”

Wu et al. (Feb 3, 2021). Safety, Tolerability, and Immunogenicity of an Inactivated SARS-CoV-2 Vaccine (CoronaVac) in Healthy Adults Aged 60 Years and Older: A Randomised, Double-Blind, Placebo-Controlled, Phase 1/2 Clinical Trial. The Lancet Infectious Diseases. 

https://www.thelancet.com/article/S1473-3099(20)30843-4/fulltext

• In a randomized, double-blind, placebo-controlled phase 1/2 trial of the inactivated SARS-CoV-2 vaccine CoronaVac conducted among healthy, seronegative adults aged ≥60 years (n=421), all adverse reactions were mild or moderate, with injection site pain as the most frequently reported reaction (9%). Seroconversion after two doses was reported in at least 90% of all dosage groups and none in the placebo groups.

Type: inactivated 

Doses: 2 doses, 14 days apart

Ella et al. (Mar 8, 2021). Safety and Immunogenicity of an Inactivated SARS-CoV-2 Vaccine, BBV152: Interim Results from a Double-Blind, Randomised, Multicentre, Phase 2 Trial, and 3-Month Follow-up of a Double-Blind, Randomised Phase 1 Trial. The Lancet Infectious Diseases. https://doi.org/10.1016/S1473-3099(21)00070-0

• Interim results from a double-blind randomized phase 2 trial (n=380) of the Bharat Biotech whole-virion inactivated SARS-CoV-2 vaccine (BBV152) show robust neutralizing titers against wild-type SARS-CoV-2 at day 56 following two doses administered on day 0 and day 28. In a plaque-reduction neutralization test, the 6 µg dose group compared to the 3 µg dose group had higher geometric mean neutralizing titers (197 vs 100) and higher proportion of seroconversion (98% vs 93%) at day 56. No significant difference was observed in the proportion of participants who reported local or systematic adverse reactions between the dose groups (20% vs 21%), and no serious adverse events were reported in the study.