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Tag: immunity
February 11, 2021
Characterization of SARS-CoV-2 RNA, Antibodies, and Neutralizing Capacity in Milk Produced by Women with COVID-19
SARS-CoV-2 RNA was not detected by RT-qPCR in breast milk samples (n=37) collected from 18 women following COVID-19 diagnosis. Breast milk was collected on average 12.0 +/- 8.9 days after onset of signs and/or symptoms. In contrast, 76% and 80% of samples contained anti-SARS-CoV-2 IgA and IgG, respectively, and 62% of samples neutralized SARS-CoV-2 in…
February 8, 2021
Antibody Responses Boosted in Seropositive Healthcare Workers after Single Dose of SARS-CoV-2 MRNA Vaccine
[Pre-print, not peer-reviewed] Among healthcare workers who received a single dose of the Pfizer/BioNTech vaccine, those who had SARS-CoV-2 infection 30-60 days prior to vaccination (n = 36) had significantly higher antibody levels at 3 weeks post-vaccination than individuals with no prior infection (n = 152). After the first vaccine dose, both previously infected and…
February 4, 2021
Impact of the B.1.1.7 Variant on Neutralizing Monoclonal Antibodies Recognizing Diverse Epitopes on SARS-CoV-2 Spike
[Pre-print, not peer reviewed] The SARS-CoV-2 B.1.1.7 variant (first identified in the UK) was shown to reduce neutralizing activity of monoclonal antibodies (mAbs) targeting subdominant epitopes in the SARS-CoV-2 spike protein. In particular, the B.1.1.7 (UK) variant reduced neutralizing activity of mAbs specific to the N-terminal domain (NTD) by up to 16-fold. NTD-specific mAbs consisted…
Dynamics of Neutralizing Antibody Titers in the Months After Severe Acute Respiratory Syndrome Coronavirus 2 Infection
Neutralizing antibody titers against SARS-CoV-2 declined by an average of 4-fold after 4 months post-symptom onset in a cohort of 32 individuals recovering from SARS-CoV-2 infection. The authors conclude that the dynamics of the antibody response to SARS-CoV-2 in the first several months after infection are consistent with what would be expected based on knowledge…
February 3, 2021
Neutralization of SARS-CoV-2 VOC 501Y.V2 by Human Antisera Elicited by Both Inactivated BBIBP-CorV and Recombinant Dimeric RBD ZF2001 Vaccines
[Pre-print, not peer-reviewed] Sera from 12 participants who received either the inactivated virus vaccine BBIP-CorV or the ZF2001 RBD protein subunit vaccine (both manufactured in China) showed neutralizing activity against the 501Y.V2 SARS-CoV-2 variant (first identified in South Africa). Neutralization was measured by microcytopathogenic effect assay and there were slightly reduced geometric mean antibody titers…
February 1, 2021
Quantification of Occupational and Community Risk Factors for SARS-CoV-2 Seropositivity Among Health Care Workers in a Large U.S. Health Care System
Adjusted SARS-CoV-2 seropositivity was estimated to be 3.8% among healthcare workers (n=10,275) at a large Atlanta health care center who participated in a survey from April-June 2020. Odds of infection were higher among those with community contact with a person known or suspected to have COVID-19 (aOR = 1.9), community COVID-19 incidence (aOR = 1.5),…
Impact of Age Gender Ethnicity and Prior Disease Status on Immunogenicity Following Administration of a Single Dose of the BNT162b2 MRNA Covid-19 Vaccine Real-World Evidence from Israeli Healthcare Workers December-January 2020
[Pre-print, not peer-reviewed] Among 514 healthcare workers in Israel who received a SARS-CoV-2 vaccine (majority Pfizer), 92% had detectable IgG antibodies 21 days post-vaccination. There was no statistically significant difference in antibody titers between males and females or by ethnicity, but titers decreased with increasing age. Individuals with prior COVID-19 who received the vaccine had…
Mapping a Pandemic SARS-CoV-2 Seropositivity in the United States
[Pre-print, not peer-reviewed] Between May and July 2020, there were an estimated 4.8 undiagnosed cases of COVID-19 for every case diagnosed in the United States, and an estimated 16.8 million undiagnosed cases by mid-July, based on findings from a serostudy conducted among adults (n = 11,3182) who had not been diagnosed with COVID-19. Undiagnosed seropositivity…
Robust Spike Antibody Responses and Increased Reactogenicity in Seropositive Individuals after a Single Dose of SARS-CoV-2 MRNA Vaccine
[Pre-print, not peer-reviewed] One dose of mRNA vaccine elicited a rapid and strong immune response among individuals already seropositive for SARS-CoV-2, with antibody titers 10-20 times higher than those of naïve vaccinees at the same timepoint. Seropositive individuals also had antibody titers that exceeded by >10-fold the median titers among individuals without previous infection who…
Assessment of Maternal and Neonatal Cord Blood SARS-CoV-2 Antibodies and Placental Transfer Ratios
IgG antibodies to SARS-CoV-2 from pregnant women with symptomatic or asymptomatic SARS-CoV-2 infection were transferred across the placenta, and cord antibody concentrations were positively correlated with maternal IgG concentrations (r=0.9). IgG antibodies were detected in cord blood from 72 of 83 newborns (87%), while IgM antibodies were not detected in any cord blood samples. Eleven…
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