Result for
Topic: Vaccines and Immunity
August 5, 2020
Estimating the Reproductive Number R 0 of SARS-CoV-2 in the United States and Eight European Countries and Implications for Vaccination
[pre-print, not peer reviewed] Ke et al. estimate that the herd immunity threshold needed to prevent sustained transmission of COVID-19 ranges between 73% and 84%. Based on these estimates and evidence that immunity may not be long-lasting, they suggest the need for repeated waves of vaccination. If mass vaccination achieves 85% immunity that lasts approximately one year, vaccination campaigns will need to occur multiple times a year. Annual vaccination or vaccination every two would be sufficient to…
July 31, 2020
ChAdOx1 NCoV-19 Vaccine Prevents SARS-CoV-2 Pneumonia in Rhesus Macaques
A single dose of a vaccine similar to one previously discovered to protect against MERS was reported by van Doremalen et al. to produce neutralizing antibodies specific to SARS-CoV-2 in both mice and rhesus macaques. A booster shot significantly improved humoral immune response in macaques. The vaccine candidate is moving on to clinical trials. van Doremalen et al. (July 30, 2020). ChAdOx1 NCoV-19 Vaccine Prevents SARS-CoV-2…
Single-Shot Ad26 Vaccine Protects against SARS-CoV-2 in Rhesus Macaques
A single dose of an adenovirus serotype 26 vaccine expressing the SARS-CoV-2 spike protein induced robust neutralizing antibody responses and provided complete or near-complete protection after SARS-CoV-2 challenge in rhesus macaques. A version of the vaccine (Ad26.COV2.S) is currently being evaluated in clinical trials. Mercado et al. (July 30, 2020). Single-Shot Ad26 Vaccine Protects against SARS-CoV-2 in Rhesus…
July 29, 2020
Evaluation of the MRNA-1273 Vaccine against SARS-CoV-2 in Nonhuman Primates
Corbett et al. report that vaccination of Indian-origin rhesus macaques with mRNA-1273, a vaccine candidate encoding the prefusion-stabilized spike protein of SARS-CoV-2, induced robust antibody and T-cell responses before challenge with SARS-CoV-2 in upper- and lower-airway. Following exposure of the animals to infectious doses of SARS-CoV-2 there was indication of rapid protection from infection and no pathologic changes in…
July 24, 2020
Immunogenicity and Safety of a Recombinant Adenovirus Type-5-Vectored COVID-19 Vaccine in Healthy Adults Aged 18 Years or Older: A Randomised, Double-Blind, Placebo-Controlled, Phase 2 Trial
Zhu et al. report findings from a phase 2 randomized, double-blind, placebo-controlled single-center (Wuhan) trial of an Ad5-vecctored COVID-19 vaccine. A total of 508 participants were randomly assigned to treatment (n=253 low dose, n=129 medium dose) or placebo (n=126; vaccine excipients with no viral particles). Both treatment groups had high seroconversion rates by 28 days (96% in the…
Safety and Immunogenicity of the ChAdOx1 NCoV-19 Vaccine against SARS-CoV-2: A Preliminary Report of a Phase 1/2, Single-Blind, Randomised Controlled Trial
Folegatti present preliminary results of a phase 1/2 single-blind, randomized multi-center (5 UK sites) trial of a chimpanzee adenovirus-vectored vaccine expressing the SARS-CoV-2 spike protein (n=543 treatment and n=534). Controls received a meningococcal conjugate vaccine. Adverse effects were more common in the treatment arm and included included pain, fever, chills, muscle ache, and malaise. No serious adverse events were reported. Cell-mediated immunity peaked on…
July 23, 2020
Kinetics and Isotype Assessment of Antibodies Targeting the Spike Protein Receptor Binding Domain of SARS-CoV-2 In COVID-19 Patients as a Function of Age and Biological Sex
[Preprint, not peer reviewed] The receptor-binding domain of the CoV spike (RBD-S) protein is important in host cell recognition and infection, and antibodies targeting this domain are often neutralizing. Graham et al. tested anti-RBD-S responses among 32 COVID-19 patients. They found that IgG, IgM, and IgA responses were all induced within 10 days following symptom onset, and IgG response was sustained over…
Potent Neutralizing Antibodies Directed to Multiple Epitopes on SARS-CoV-2 Spike
A large number of monoclonal antibodies that potently neutralize the SARS-CoV-2 virus were identified from COVID-19 cases from New York. Liu et al. report the isolation of 61 SARS-CoV-2-neutralizing monoclonal antibodies from 5 infected patients hospitalized with severe disease at the Columbia University Irving Medical Center in New York City. Among these are 19 antibodies that potently…
July 20, 2020
Articles Immunogenicity and Safety of a Recombinant Adenovirus Type-5-Vectored COVID-19 Vaccine in Healthy Adults Aged 18 Years or Older : A Randomised , Double-Blind , Placebo- Controlled , Phase 2 Trial
Zhu et al. conducted a randomized, double-blind, placebo-controlled, phase 2 trial of the Ad5-vectored COVID-19 vaccine to determine the immunogenicity and incidence of adverse reactions. Both doses of the vaccine induced significant neutralizing antibody responses to live SARS-CoV-2. Evidence of antigen-specific T-cell responses were observed in 88-90% of vaccine recipients. Within 14 days, 72% of participants in one vaccine dose…
July 15, 2020
An MRNA Vaccine against SARS-CoV-2 — Preliminary Report
The candidate vaccine mRNA-1273 was shown to induce antibody and T-cell immune responses in all participants (n=45). Jackson et al. conducted a phase 1, dose-escalation, open-label trial including 45 healthy adults, to test the candidate vaccine mRNA-1273 encoding the stabilized prefusion of SARS-CoV-2 spike protein. Participants received two vaccinations, 28 days apart in three dose groups. After the first vaccination,…
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