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Tag: immunity
April 26, 2021
Re-Infection with SARS-CoV-2 in Patients Undergoing Serial Laboratory Testing
A low frequency of SARS-CoV-2 re-infection (0.7%) was identified in a large cohort of patients (n = 9,119) who received serial tests at 62 health care facilities in the United States between December 1, 2019 and November 13, 2020. Re-infection was defined as two positive tests separated by an interval of more than 90 days…
COVID-19 Vaccine Coverage in Health-Care Workers in England and Effectiveness of BNT162b2 MRNA Vaccine against Infection (SIREN): A Prospective, Multicentre, Cohort Study
The Pfizer-BioNTech vaccine showed 70% effectiveness against SARS-CoV-2 infection 21 days after the first dose, and 85% effectiveness 7 days after two doses among staff working in publicly-funded hospitals in the UK. Participants were followed for two months, for a total of 1,106,905 person-days. During follow-up, 977 new infections occurred among unvaccinated individuals (14 per…
Protection of Previous SARS-CoV-2 Infection Is Similar to That of BNT162b2 Vaccine Protection A Three-Month Nationwide Experience from Israel
[Pre-print, not peer-reviewed] A population-based study in Israel found that the level of protection against reinfection conferred by prior infection with SARS-CoV-2 within the last 6 months was similar to that elicited by the Pfizer-BioNTech vaccine among people who had no prior infection. Vaccine effectiveness against severe disease was 66% for individuals followed from the…
Asymptomatic and Symptomatic SARS-CoV-2 Infections Elicit Polyfunctional Antibodies
Cellular assays evaluating antibody-dependent cellular cytotoxicity (ADCC) combined with assessments of antibody titers and neutralization activity indicated that asymptomatic infection with SARS-CoV-2 induces a polyfunctional antibody response. In this study, antibody responses were slightly lower among asymptomatic than symptomatic individuals, but did not differ in neutralization activity or the ability to trigger ADCC and complement…
April 21, 2021
Postvaccination SARS-CoV-2 Infections Among Skilled Nursing Facility Residents and Staff Members — Chicago, Illinois, December 2020–March 2021
Twenty-two possible breakthrough SARS-CoV-2 infections (infection ≥14 days after the second vaccine dose) were identified among skilled nursing facility staff (n = 10) and residents (n = 12) across 15 facilities in the Chicago, IL area. Among these cases, 14 (64%) were asymptomatic, two residents were hospitalized, and one resident died due to multiple concurrent…
Asymptomatic or Mild Symptomatic SARS-CoV-2 Infection Elicits Durable Neutralizing Antibody Responses in Children and Adolescents
[Pre-print, not peer-reviewed] Children and adolescents with mild or asymptomatic SARS-CoV-2 infection (n = 69) had robust IgM, IgA, and IgG antibody responses to a range of antigens at the time of infection, and at 2- and 4- month follow-up. Neutralizing activity was still detectable 4 months after infection in 94% of participants, and antibody…
April 20, 2021
Serological Investigation of Asymptomatic Cases of SARS-CoV-2 Infection Reveals Weak and Declining Antibody Responses
SARS-CoV-2 anti-nucleocapsid IgM antibodies were detected in a small proportion (6%) of asymptomatic food workers (n=508) in Wuhan in April 2020. In a follow-up survey among 21 of seropositive participants, IgM levels had declined by up to 50% in 90% of individuals. In comparison to a cohort of symptomatic patients 2 months after infection, asymptomatic…
April 19, 2021
Humoral and Cellular Immune Responses against SARS-CoV-2 Variants and Human Coronaviruses after Single BNT162b2 Vaccination
[Pre-print, not peer-reviewed] An assessment of humoral and T cell responses against a wild type SARS-CoV-2 strain, variants of concern (B.1.1.7, B.1.351, and P.1), and endemic human coronaviruses (hCov) induced after the Pfizer-BioNTech vaccine found that IgG against the receptor-binding domain of the SARS-CoV-2 S protein was readily detectable at day 14, but inhibition of…
April 15, 2021
Vaccination Boosts Protective Responses and Counters SARS-CoV-2-Induced Pathogenic Memory B Cells
[Pre-print, not peer-reviewed] SARS-CoV-2 specific B cells isolated from individuals who had recovered from SARS-CoV-2 infection appeared similar to B cells isolated previously described in individuals with chronic infections or inflammation (IgD negative, CD27 negative), according to a longitudinal study of convalescent individuals (n=22). After vaccination, the frequency of IgD/CD27 negative cells (“double negative”) decreased….
Early T Cell and Binding Antibody Responses Are Associated with Covid-19 RNA Vaccine Efficacy Onset
In a cohort of 20 healthcare workers receiving the first dose of the Pfizer-BioNTech vaccine, SARS-CoV-2 spike-specific memory T-cell and binding antibody responses were universally detected prior to the time where vaccine efficacy is first detected in clinical trials (day 12). In contrast, receptor blocking and neutralizing antibodies were not detected on day 7 and…
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