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Tag: immunity
June 1, 2021
Prior COVID-19 Protects against Reinfection, Even in the Absence of Detectable Antibodies
Risk of SARS-CoV-2 infection in the UK between August 2020 and January 2021 was 80% lower among individuals with lab-confirmed infection but later testing antibody-negative (i.e. RNA-positive antibody-negative) compared to individuals who did not have infection (no test or RNA-negative and antibody-negative) during March to July 2020, according to an analysis of datasets obtained from…
A Population-Based Analysis of the Longevity of SARS-CoV-2 Antibody Seropositivity in the United States
An observational study of 39,086 US individuals with PCR-confirmed COVID-19 followed up to 10 months from March 2020 to January 2021 found that prevalence of anti-SARS-CoV-2 IgG spike (S) and nucleocapsid (N) antibodies reached approximately 90% 21 days after infection, then declined to 88% for S antibodies and 68% for N antibodies after 10 months….
May 28, 2021
The Humoral Response to the BNT162b2 Vaccine in Hemodialysis Patients
[Pre-print, not peer-reviewed] Anti-SARS-CoV-2 spike antibodies were detected in 80% of chronic hemodialysis patients (n=66) 28 days after a single dose of the Pfizer-BioNTech vaccine in a cohort study in Toronto, Canada. However, only 23% mounted a robust response defined by exceeding the median level of anti-spike antibodies observed in serum of healthy convalescent controls…
Reduced Sensitivity of Infectious SARS-CoV-2 Variant B.1.617.2 to Monoclonal Antibodies and Sera from Convalescent and Vaccinated Individuals
[Pre-print, not peer-reviewed] The SARS-CoV-2 B.1.617.2 variant of concern, first described in India, was experimentally shown to completely escape neutralizing activity from the monoclonal antibody (mAb) bamlanivimab (made by Eli Lilly), while neutralizing activity of etesivimab (also Eli Lilly), casirivimab and imdevimab (Regeneron) were preserved. Neutralizing activity of sera from 56 individuals recovered from critical,…
Seroprevalence of SARS-CoV-2 Antibodies in Seattle, Washington: October 2019–April 2020
Residual clinical samples collected from 766 Seattle-area adults during October 2019 to April 2020 showed that anti-SARS-CoV-2 antibodies were not detected until mid-March 2020. Estimated antibody prevalence from March 5-April 1, 2020 was 1.2%, which was 11 times greater than the number of confirmed cases in King County, which includes Seattle, as of April 1….
Risk of Reinfection after Seroconversion to SARS-CoV-2: A Population-Based Propensity-Score Matched Cohort Study
Swiss adults who were seropositive for SARS-CoV-2 IgG antibodies were less likely to have a SARS-CoV-2 PCR positive test than propensity-score-matched seronegative adults in the 8 months following antibody measurements. Of the 498 seropositive individuals, only 5 (1%) retested positive (likely indicative of reinfection) after a mean follow-up of 36 weeks. In contrast, 154 of…
E484K as an Innovative Phylogenetic Event for Viral Evolution: Genomic Analysis of the E484K Spike Mutation in SARS-CoV-2 Lineages from Brazil
Genomic and phylogenetic analyses of SARS-CoV-2 genomes with the E484K mutation sequenced from samples in Brazil in 2020 showed that over 40% of sequenced genomes had this mutation by October 2020 across three distinct lineages (P.1, P.2, and N.9) in four different regions. Modeling of a random set of sequenced genomes suggests that the mutation…
May 27, 2021
Safety, Immunogenicity, and Efficacy of the BNT162b2 Covid-19 Vaccine in Adolescents
A randomized trial of the Pfizer-BioNTech vaccine (BNT162b2) among adolescents ages 12-15 reported vaccine efficacy of 100% (75.3-100%) against COVID-19 for the 2-dose vaccine series. There were 16 cases of COVID-19 among 1,129 placebo recipients and no COVID-19 cases among 1,131 vaccine recipients that occurred 7 or more days after the second dose among participants…
Cellular and Humoral Response after MRNA-1273 SARS-CoV-2 Vaccine in Kidney Transplant Recipients
Only 35 of 117 (30%) kidney transplant recipients without known prior SARS-CoV-2 infection had a detectable humoral immune response (anti-spike IgG and/or IgM antibodies) to the Moderna vaccine two weeks after the second dose, while 55% had a detectable cellular immune response. Development of both humoral and cellular immune responses was observed in 20% of…
Standardised Quantitative Neutralisation Responses to SARS-CoV-2 Variants of Concern by Convalescent Anti-Sera from First Wave Infections of UK Health Care Workers and Patients
[Pre-print, not peer-reviewed] Neutralizing activity of convalescent plasma collected from patients and healthcare workers infected during the first wave of the COVID-19 pandemic between July and September 2020 (n=61) was reduced by 2-fold against the B.1.1.7 variant and by 8-fold against the B.1.351 and P.1 variant compared to the parent B.1 strain. Neutralizing activity correlated…
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