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Topic: Vaccines and Immunity
February 17, 2021
SARS-CoV-2 Variants Show Resistance to Neutralization by Many Monoclonal and Serum-Derived Polyclonal Antibodies
[Pre-print, not peer-reviewed] Most convalescent sera from people who had recovered from COVID-19 and virtually all Pfizer-BioNTech mRNA vaccine-induced immune sera were shown to have diminished neutralizing activity against engineered SARS-CoV-2 strains including a chimeric strain combining a strain identified in Washington state with a B.1.351 spike gene (Wash SA-B.1.351 strain), or recombinant viruses containing…
February 16, 2021
Persistence of SARS-CoV-2 Specific B- and T-Cell Responses in Convalescent COVID-19 Patients 6-8 Months after the Infection
Anti-SARS-CoV-2 antibodies were detected in 85% of 119 samples collected from 88 COVID-19 convalescent donors within 4 weeks post symptom onset. IgM/IgA levels declined after 1 month, while IgG levels remained relatively stable and were detected in 80% of samples up to 6-8 months irrespective of disease severity. SARS-CoV-2-specific memory B- and T-cell responses developed…
Sensitivity of Infectious SARS-CoV-2 B.1.1.7 and B.1.351 Variants to Neutralizing Antibodies
[Pre-print, not peer reviewed] The SARS-CoV-2 B.1.1.7 variant (first described in the UK) was experimentally shown to have similar sensitivity to the neutralizing activity of convalescent sera (n=83) collected up to 9 months post symptom onset compared to the wild-type virus. In contrast, neutralizing titers had a mean 6-fold reduction against the B.1.351 variant (first…
Longitudinal Analysis of Antibody Response Following SARS-CoV-2 Infection in Pregnancy: From the First Trimester to Delivery
In a cohort of 17 SARS-CoV-2 PCR-positive pregnant women followed from the end of the first trimester to delivery, IgG non-neutralizing antibodies (nNAbs) were detected in 71% (12 of 17), while neutralizing antibodies (NAbs) were detected in 53% of individuals (9 of the 12 who seroconverted with IgG nNAbs). Levels of NAbs remained stable throughout…
Discrete SARS-CoV-2 Antibody Titers Track with Functional Humoral Stability
There may be a distinct threshold of immune activity, defined by the level of antibodies, in response to SARS-CoV-2 infection that is required to elicit a vigorous humoral and cellular response necessary to prevent subsequent re-infection. These conclusions were based on a community-based surveillance study of 120 SARS-CoV-2 convalescent patients, which found that sustained functional…
Reports of Anaphylaxis After Receipt of MRNA COVID-19 Vaccines in the US—December 14, 2020-January 18, 2021
The CDC identified 66 reports of anaphylaxis from the Vaccine Adverse Event Reporting System (VAERS) during December 14, 2020 to January 18, 2021 (47 cases out of nearly 10 million Pfizer vaccine doses and 19 cases out of nearly 7.6 million Moderna vaccine doses). All cases were treated in healthcare settings, and no deaths from…
February 13, 2021
Safety and Efficacy of the ChAdOx1 NCoV-19 (AZD1222) Covid-19 Vaccine against the B.1.351 Variant in South Africa
[pre-print; not peer-reviewed] A randomized trial conducted in South Africa found the incidence of COVID-19 >14 days after the second dose of the AstraZeneca-Oxford SARS-CoV-2 vaccine was 93.6 per 1,000 person-years (23 cases among 717 participants) in the vaccine group and 73.1 per 1,000 person-years (19 cases among 750 participants) in the placebo group, yielding…
Impact of Age, Ethnicity, Sex and Prior Infection Status on Immunogenicity Following a Single Dose of the BNT162b2 MRNA COVID-19 Vaccine: Real-World Evidence from Healthcare Workers, Israel, December 2020 to January 2021
A single dose of the Pfizer SARS-CoV-2 vaccine produced detectable anti-SARS-CoV-2 spike IgG antibodies 21 days after vaccination in 92% (n=475) of a cohort of healthcare workers in Israel, including in 92% (n=458) of people who had no history of COVID-19 infection. The 39 healthcare workers who did not respond to the first dose were…
February 11, 2021
Lasting Antibody and T Cell Responses to SARS-CoV-2 in COVID-19 Patients Three Months after Infection
In a longitudinal study of 25 convalescent SARS-CoV-2 positive patients, approximately 65% of patients had detectable T cell responses 3-4 months post-symptom onset (PSO) despite all patients seroconverting. All patients had detectable IgG against the nucleocapsid (N) and spike (S) protein as well as detectable IgG and IgM responses against the receptor-binding domain (RBD); all…
Impact of COVID-19 Vaccination Program on Healthcare Worker Infections in an Academic Hospital
An academic hospital in Virginia reported a 25% decrease in health care worker (HCW) SARS-CoV-2 infections 6 days after beginning employee immunizations. Vaccines included both the Pfizer vaccine initiated on December 12, 2020 and the Moderna vaccine initiated on December 28, 2020. After achieving 60% vaccination coverage of the 1st dose, infections decreased by 50%….
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