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Tag: immunity
April 15, 2021
Sera Neutralizing Activities against SARS-CoV-2 and Multiple Variants Six Month after Hospitalization for COVID-19
Neutralizing activity in sera of SARS-CoV-2 infected individuals (n=104) against the variants D614G, B.1.1.7, and P.1 up to 6 months after infection was similar compared to the prototypic strain isolated originally in Wuhan, but was reduced 3-fold against the B.1.351 variant. Similar to other studies, anti-spike and anti-nucleocapsid IgG levels waned over time (2.8% reverted…
SARS-CoV-2 Antibody Response in Persons with Past Natural Infection
Vaccine-elicited neutralizing antibody geometric mean titers (GMT) among healthcare workers who received the first dose of the Pfizer-BioNTech vaccine 1-2 months, 2-3 months, and more than 3 months after a prior SARS-CoV-2 infection were 437, 559, and 694 arbitrary units/mL, respectively. In contrast, healthcare workers with no prior infection had a GMT of 118 units/mL…
April 14, 2021
Detection of SARS-CoV-2 Specific IgA in the Human Milk of COVID-19 Vaccinated Lactating Health Care Workers
[Pre-print, not peer-reviewed] SARS-CoV-2 specific IgA and IgG were detected in milk and plasma samples from 22 lactating healthcare workers who had received either the Moderna or Pfizer-BioNTech vaccines, with peak levels occurring 7-10 days after the second dose. Samples were collected prior to vaccination, after the first dose, and after the second dose in…
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
Antibody Responses in Elderly Residential Care Persons Following COVID-19 MRNA Vaccination
[Pre-print, not peer-reviewed] While all fully vaccinated long-term care residents (n = 70) in a cross-sectional study in the Pittsburg region between March 15 and April 1, 2021 had detectable SARS-CoV-2 antibodies, levels tended to be lower among those who were male, older, used steroid medications, or had a longer length of time since vaccination….
April 7, 2021
Antibody Persistence through 6 Months after the Second Dose of MRNA-1273 Vaccine for Covid-19
Neutralizing antibody activity elicited by the Moderna vaccine remained high 6 months after the second dose in all 33 adults in an ongoing phase 1 trial, as measured by 3 different serologic assays. Binding antibody half-life estimates after day 43 for all the participants were 52 days when calculated via an exponential decay model (assumes…
April 5, 2021
Antibody Responses to the BNT162b2 MRNA Vaccine in Individuals Previously Infected with SARS-CoV-2
Among healthcare workers in California who received the Pfizer-BioNTech vaccine (n = 1,090), spike-specific IgG antibody levels and ACE2 antibody binding inhibition responses were similar between individuals who had been previously infected with SARS-CoV-2 and received a single dose (n = 35), and those who had no prior infection and received both vaccine doses (n…
SARS-CoV-2 Infection Is Asymptomatic in Nearly Half of Adults with Robust Anti-Spike Protein Receptor-Binding Domain Antibody Response
In a study of 4996 participants (aged 18–82 years, 34.5% men) from Greece with plasma antibodies against SARS-CoV-2 nucleocapsid protein between June and November 2020, 49% of seropositive cases (39/79) reported no history of SARS-CoV-2 infection-related clinical symptoms. The majority of SARS-CoV-2 asymptomatic infections were “unsuspected” cases (26/39) who had no known contact with a…
April 2, 2021
Genetic Evidence and Host Immune Response in Persons Reinfected with SARS-CoV-2, Brazil
4 cases of possible SARS-CoV-2 reinfection characterized by a more severe second episode were identified in a case series in Brazil. In March 2020, all patients recovered from a mild course of COVID-19 and retested with negative PCR results during early April. In the last week of May, all 4 cases reported SARS-CoV-2 symptoms and…
April 1, 2021
Longitudinal Dynamics of Antibody Responses in Recovered COVID-19 Patients
SARS-CoV-2-specific IgG antibody titers gradually increased with neutralizing antibody titers while IgM titers more quickly waned in a study of the antibody response dynamics in 24 COVID-19 recovered patients followed up to 42 weeks. While IgG titers were higher among severe than among mild cases, titers did not decline significantly over time in either group….
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