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Tag: immunity
March 30, 2021
Verified infections with endemic common cold coronaviruses do not entail significant protection against SARS-CoV-2
A previous confirmed seasonal coronavirus infection does not appear to provide protection against subsequent infection with SARS-CoV-2, according to analysis of a large database of respiratory specimens in Sweden. The analysis is based on a database of >75,000 respiratory specimens collected from 2013-2020 and linked to 10,000 samples collected during the pandemic (February-November 2020). There…
SARS-CoV-2 Variant B.1.1.7 Caused HLA-A2+ CD8+ T Cell Epitope Mutations for Impaired Cellular Immune Response
[Pre-print, not peer-reviewed] The SARS-CoV-2 B.1.1.7 variant is associated with reduced CD8+ T cell activation due to at least two specific mutations in ORF1. The authors used algorithms to predict HLA-A2 binding epitopes in both the B.1.1.7 strain and the ancestral Wuhan strain and determined whether these epitopes could activate CD8+ T cells using an…
Dynamics of SARS-CoV-2 Neutralising Antibody Responses and Duration of Immunity: A Longitudinal Study
Five distinct patterns of SARS-CoV-2 neutralizing antibody dynamics were found in a longitudinal study of 164 SARS-CoV-2-infected patients in Singapore with follow-up of up to 180 days post-symptom onset. The different dynamics were defined by the trajectory by which antibody levels waned or evolved. Persistent dynamics, observed in the largest group of patients (32%), was…
March 25, 2021
Genomic Evidence of SARS-CoV-2 Reinfection Involving E484K Spike Mutation, Brazil
SARS-CoV-2 reinfection with a variant harboring the E484K mutation (occurring in the P.2 variant) was confirmed by genome sequencing in a case study in Brazil. The primary infection occurred in May 2020 by a widely circulating variant B.1.1.33 without the E484K mutation, while the reinfection occurred 147 days later in October 2020. Findings from this…
March 23, 2021
Association of Age With SARS-CoV-2 Antibody Response
SARS-CoV-2 antibody responses are distinct in different age groups, according to a cross-sectional study of a New York City hospital using 31,426 SARS-CoV-2 antibody test results from pediatric and adult patients. IgG levels were negatively correlated with age in the pediatric population (r = -0.45, P < .001), but moderately positively correlated with age in…
Exposure to SARS-CoV-2 Generates T-Cell Memory in the Absence of a Detectable Viral Infection
Exposure to SARS-CoV-2 may still lead to the development of SARS-CoV-2-specific memory T cells in the absence of detectable SARS-CoV-2 virus or antibodies against SARS-CoV-2 antigens (spike and nucleocapsid). In blood samples collected from 69 individuals between 48 and 86 days after close contact with an individual with a confirmed SARS-CoV-2 infection, 58% and 14%…
Risk of Reinfection after Seroconversion to SARS-CoV-2 A Population-Based Propensity-Score Matched Cohort Study
[Pre-print, not peer-reviewed] 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…
Reduced BNT162b2 MRNA Vaccine Response in SARS-CoV-2-Naive Nursing Home Residents
[Pre-print, not peer-reviewed] Nursing home (NH) residents had blunted antibody responses following vaccination with BNT162b2 mRNA vaccine (Moderna) when compared to healthcare workers. SARS-CoV-2-naive NH residents mounted antibody responses with nearly 4-fold lower median neutralization titers and half the anti-spike level compared to SARS-CoV-2-naive healthcare workers. In contrast, NH residents who had recovered from infection…
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…
Neutralizing Antibodies Against SARS-CoV-2 Variants After Infection and Vaccination
Neutralizing antibody activity against four SARS-CoV-2 variants, including B.1, B.1.1.7, and N501Y was maintain in sera from individuals with infection- and vaccine-induced antibodies. There was minimal reductions in serum neutralization observed across four representative SARS-CoV-2 strains. Serum was obtained from adults (n=20) hospitalized with COVID-19 5 to 19 days after symptom onset, convalescent individuals (n=2)…
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