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Tag: antibodies
May 6, 2021
BNT162b2 MRNA COVID-19 Vaccine Induces Antibodies of Broader Cross-reactivity than Natural Infection but Recognition of Mutant Viruses Is up to 10-fold Reduced
Antibodies induced by the Pfizer-BioNTech vaccine had higher binding capacities (avidity) than antibodies induced by natural infection against the receptor binding domain (RBD) containing mutations representative of circulating SARS-CoV-2 variants of concern (N501Y, K417N, E484K, and a combination of all three). Vaccine-induced sera (n=6) had 2.5- to 3-fold reduced binding to a RBD containing the…
May 4, 2021
SARS -CoV-2 T-Cell Immunity to Variants of Concern Following Vaccination
[Pre-print, not peer-reviewed] A study using two standardized, functional assays to measure memory T cell immunity to SARS-CoV-2 found that individuals vaccinated with the COVID-19 mRNA vaccines (n=29) mounted a more robust T cell response than convalescent patients (n=19) or healthy controls with no prior infection (n=25). The assay was based upon the “Quantiferon Gold”…
SARS-CoV-2 antibody-positivity protects against reinfection for at least seven months with 95% efficacy
Incidence of SARS-CoV-2 infection was 95% lower among persons with prior SARS-CoV-2 infection, indicated by seropositivity, in a cohort study in Qatar. In the study, 129 of 43,044 seropositive persons (0.3%) followed for a median of 16 weeks had at least one positive PCR test supported by evidence of reinfection at least 14 days after…
April 30, 2021
The Impact on Infectivity and Neutralization Efficiency of SARS-CoV-2 Lineage B.1.351 Pseudovirus
An in-vitro comparison of SARS-CoV-2 spike pseudoviruses carrying mutations characteristic of the B.1.351 lineage (N501Y, K417N, and E484K) and the original D614G lineage found that the viruses in the B.1.351 lineage demonstrated increased infectivity in cellular assays. Additionally, the monoclonal antibody imdevimab neutralized all three B.1.351 lineage viruses, while neutralization by the monoclonal antibody casirivimab…
April 29, 2021
Antibody Response to Coronavirus Disease 2019 (COVID-19) Messenger RNA Vaccination in Pregnant Women and Transplacental Passage Into Cord Blood
Among 122 pregnant women who delivered on or after 35 weeks gestation and received a COVID-19 mRNA vaccine by the time of delivery (n= 55 first dose, n=67 both doses), anti-SARS-CoV-2 IgG antibodies were detected in maternal blood as early as 5 days and in cord blood as early as 16 days after the first…
Maternal Antibody Response, Neutralizing Potency, and Placental Antibody Transfer After Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) Infection
Among maternal blood samples from SARS-CoV-2 positive patients obtained after delivery (n=32), higher median anti-RBD IgG titers were significantly associated with symptomatic (vs. asymptomatic) infection but not with having a PCR-positive test more than 14 days earlier (vs. PCR-positive test within 14 days). Paired cord blood samples also obtained after delivery show that median cord/maternal…
April 22, 2021
Immunogenicity of SARS-CoV-2 Vaccine in Dialysis
[Pre-print, not peer-reviewed] 89% of 186 dialysis patients developed anti-SARS-CoV-2 spike antibodies following two doses of mRNA vaccines (Pfizer-BioNTech and Moderna). Among patients without prior SARS-CoV-2 infection (n=148), the seropositivity rate was 86%. A majority (70%) of seropositive patients had maximum titers for anti-spike IgG antibodies at least 14 days after the second dose. No…
April 21, 2021
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…
Identification of Natural SARS-CoV-2 Infection in Seroprevalence Studies among Vaccinated Populations
[Pre-print, not peer-reviewed] Anti-nucleocapsid protein (N) antibodies were found to be an accurate method for differentiating between antibodies produced by natural infection and antibodies produced in response to vaccination, according to a study of healthcare workers (n=82). Participants were tested for anti-spike (S) IgG antibodies and anti-N IgG at two time points. No participants were…
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