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Tag: transmission
May 26, 2021
Estimating Infectiousness throughout SARS-CoV-2 Infection Course
An analysis of 936,423 SARS-CoV-2 RT-PCR-positive samples from hospitalized and non-hospitalized persons in Germany found that high viral loads (> 109 copies per swab) were found in 8% of subjects, 1/3 of whom were pre-symptomatic, asymptomatic, or mildly symptomatic. The mean number of days from onset of viral shedding to peak viral load was 4.3….
May 24, 2021
Epidemiological Characteristics of Three SARS-CoV-2 Variants of Concern and Implications for Future COVID-19 Pandemic Outcomes
[Pre-print, not peer-reviewed] A modeling study that accounted for under detection of infection, seasonality, concurrent use of non-pharmaceutical interventions, and mass vaccination, found that the B.1.1.7 variant was 47% more transmissible but infrequently escaped immunity from prior wild-type infection; B.1.351 was 32% more transmissible and had 61% immune escape; and P.1 was 43% more transmissible…
COVID-19 Mitigation Practices and COVID-19 Rates in Schools Report on Data from Florida New York and Massachusetts
[Pre-print, not peer-reviewed] A report of SARS-CoV-2 mitigation practices and infection rates in schools in Florida, New York, and Massachusetts during the 2020-2021 school year found higher infection rates among students attending schools with lower in-person density, but no association with rates among staff. The authors suggest these results could be attributed to a protective…
May 21, 2021
Mask Use and Ventilation Improvements to Reduce COVID-19 Incidence in Elementary Schools — Georgia, November 16–December 11, 2020
An analysis of COVID-19 incidence in K-5 public schools in Georgia (N=169 schools, 91,893 students) found that incidence was 37% lower in schools that required teachers and staff to wear masks and 39% lower in schools that improved ventilation. Incorporating ventilation strategies to dilute airborne particles (opening windows and doors and/or using fans) was associated…
May 20, 2021
Characteristics of COVID-19 Cases and Outbreaks at Child Care Facilities — District of Columbia, July–December 2020
24% of 469 licensed childcare facilities in Washington, DC reported at least one SARS-CoV-2 infection from July to December 2020, but facility-associated outbreaks (defined as two or more linked cases within a facility) only occurred in 6% of facilities. Among the 316 total cases, 56% were among teachers or staff and 49% occurred during outbreaks….
May 19, 2021
Rapidly Emerging SARS-CoV-2 B.1.1.7 Sub-Lineage in the United States of America with Spike Protein D178H and Membrane Protein V70L Mutations
[Pre-print, not peer-reviewed] Genomic surveillance of SARS-CoV-2 cases identified an expanding US-specific sub-lineage of the B.1.1.7 variant. This sub-lineage is characterized with sequential acquisition of a membrane protein mutation, V20L, in November 2020 and a spike mutation, D178H, in early February 2021. The proportion of B.1.1.7 isolates in the US belonging to this sub-lineage increased…
SARS-CoV-2 Superspread in Fitness Center, Hong Kong, China, March 2021
A SARS-CoV-2 superspreading event in a fitness center in Hong Kong that resulted in 102 cases likely occurred due to lack of mask wearing during exercise and poor ventilation. The outbreak was detected following investigation of a fitness trainer who worked at the facility who tested positive in a voluntary screening program. 45% of cases…
May 18, 2021
Susceptibility and Infectiousness of Children and Adults with SARS-CoV-2 Variant B.1.1.7 Deduced from Three Daycare Centre Outbreaks and Related Household Situations Germany 2021
[Pre-print, not peer-reviewed] Secondary attack rates (SARs) were 17-37% in three kindergarten schools in Germany during three SARS-CoV-2 outbreaks likely caused by the B.1.1.7 variant. A majority (>80%) of secondary cases occurred within 7 days. The pooled household SAR was 37% after excluding single-occupant households and households with another possible index case. Notably, the attack…
Size and Duration of COVID-19 Clusters Go along with a High SARS-CoV-2 Viral Load: A Spatio-Temporal Investigation in Vaud State, Switzerland
Clustering of SARS-CoV-2 cases in Switzerland from January to June 2020 by region and date of diagnosis found that of the 457 clusters with significantly higher risk of infection compared to the surrounding region, 57% had at least one person with extremely high viral load (>1 billion copies/mL). Clusters with the highest viral loads tended…
May 17, 2021
Asymptomatic SARS-CoV-2-Infected Children Attending Hospital with Non-COVID-19 Diagnoses, March 2020-February 2021
A surveillance study conducted between March 1, 2020 and February 21, 2021 in the UK found that out of 1,427 pediatric patients admitted to the hospital, 80 (5.6%) tested positive for SARS-CoV-2, of which 52 (65%) had symptoms compatible with COVID-19, 16 (20%) were asymptomatic, and 12 (15%) were “unclear” because of overlapping symptoms between…
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