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Tag: variant
April 15, 2021
MRNA Vaccination Compared to Infection Elicits an IgG-Predominant Response with Greater SARS-CoV-2 Specificity and Similar Decrease in Variant Spike Recognition
[Pre-print, not peer-reviewed] Immune serological responses against SARS-CoV-2 among 55 recipients of the Pfizer-BioNTech vaccine were dominated by IgG antibody responses compared to more diverse responses (including IgM and IgA) elicited by natural infection among 100 COVID-19 patients. Vaccinated individuals also had decreased breadth of antibody response against endemic human coronaviruses compared to convalescent individuals….
April 14, 2021
SARS-CoV-2 Spike E484K Mutation Reduces Antibody Neutralisation
An in-vitro study of serum from persons with either prior SARS-CoV-2 infection or two doses of the Pfizer-BioNTech vaccine (N=34) found that antibody neutralization in all samples was reduced against SARS-CoV-2 virus with a single spike E484K mutation compared to the USA-WA1/2020 strain (the strain first detected in the US). The largest reductions in antibody…
April 12, 2021
Evidence for Increased Breakthrough Rates of SARS-CoV-2 Variants of Concern in BNT162b2 MRNA Vaccinated Individuals
[Pre-print, not peer-reviewed] A case-control study of individuals with SARS-CoV-2 infection in Israel who received the Pfizer vaccine (cases) versus unvaccinated carriers (controls) found that the predominant SARS-CoV-2 variant among vaccine recipients with a positive SARS-CoV-2 PCR result differed depending on their timing in the vaccine course. Compared to controls, vaccinated individuals infected at least…
Neutralization of SARS-CoV-2 Variants by Convalescent and Vaccinated Serum
[Pre-print, not peer-reviewed] Sera from convalescent individuals (n = 44) and individuals who received the Pfizer-BioNTech vaccine (n = 51) showed reduced neutralization activity against the SARS-CoV-2 B.1.1.7 and B.1.351 variants. Among vaccinated individuals, the geometric mean 50% receptor binding domain (RBD) antibody concentration was 1.3-fold lower for the B.1.1.7 variant and 1.4-fold lower for…
March 19, 2021
SARS-CoV-2 501Y.V2 variants lack higher infectivity but do have immune escape
The infectivity of the 501Y.V2 variants (which include the B.1.351 variant that was first identified in South Africa) was not significantly different than the reference strain (D614G) across multiple cell types. The neutralizing activity of multiple RBD-targeting monoclonal antibodies decreased significantly, and polyclonal antibodies (from RBD-immunized mouse sera and from SARS-CoV-2 convalescent sera) also had…
March 18, 2021
Estimating the Increased Transmissibility of the B.1.1.7 Strain over Previously Circulating Strains in England Using Fractions of GISAID Sequences and the Distribution of Serial Intervals.
[Pre-print, not peer-reviewed] The SARS-CoV-2 B.1.1.7 strain is suggested to be 40% more transmissible than previously circulating strains, according to a model-based analysis using the time course of the proportion of SARS-CoV-2 infections with the B.1.1.7 variant applied to SARS-CoV-2 genome sequence data and the distribution of serial intervals in England. For mitigation, the authors…
March 17, 2021
Efficacy of the ChAdOx1 NCoV-19 Covid-19 Vaccine against the B.1.351 Variant
Two doses of the Oxford-AstraZeneca (ChAdOx1 nCoV-19) vaccine did not show protection against mild-to-moderate COVID-19 among people infected with the B.1.351 variant in a multicenter randomized trial in South Africa. Mild-to-moderate COVID-19 developed in 23 of 717 placebo recipients (3.2%) and in 19 of 750 vaccine recipients (2.5%), for an efficacy of 21.9%. Among the…
February 23, 2021
Characterizing SARS-CoV-2 Genome Diversity Circulating in South American Countries: Signatures of Potentially Emergent Lineages?
Analysis of nearly 6,000 publicly available SARS-CoV-2 genome assemblies in South America identified a total of 169 circulating lineages across 16 South American countries, with the B lineage the predominantly circulating lineage. Lineages of concern that were identified include the P.1 variant (94 genomes) and the B.1.1.7 variant (28 genomes), with both variants displaying 33…
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