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Open AccessJournal ArticleDOI

Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection.

TLDR
It is shown that neutralization level is highly predictive of immune protection, and an evidence-based model of SARS-CoV-2 immune protection that will assist in developing vaccine strategies to control the future trajectory of the pandemic is provided.
Abstract
Predictive models of immune protection from COVID-19 are urgently needed to identify correlates of protection to assist in the future deployment of vaccines. To address this, we analyzed the relationship between in vitro neutralization levels and the observed protection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection using data from seven current vaccines and from convalescent cohorts. We estimated the neutralization level for 50% protection against detectable SARS-CoV-2 infection to be 20.2% of the mean convalescent level (95% confidence interval (CI) = 14.4–28.4%). The estimated neutralization level required for 50% protection from severe infection was significantly lower (3% of the mean convalescent level; 95% CI = 0.7–13%, P = 0.0004). Modeling of the decay of the neutralization titer over the first 250 d after immunization predicts that a significant loss in protection from SARS-CoV-2 infection will occur, although protection from severe disease should be largely retained. Neutralization titers against some SARS-CoV-2 variants of concern are reduced compared with the vaccine strain, and our model predicts the relationship between neutralization and efficacy against viral variants. Here, we show that neutralization level is highly predictive of immune protection, and provide an evidence-based model of SARS-CoV-2 immune protection that will assist in developing vaccine strategies to control the future trajectory of the pandemic. Estimates of the levels of neutralizing antibodies necessary for protection against symptomatic SARS-CoV-2 or severe COVID-19 are a fraction of the mean level in convalescent serum and will be useful in guiding vaccine rollouts.

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Impact of vaccination on the symptoms of hospitalised patients with SARS-CoV-2 Delta variant (B.1.617.1) infection

TL;DR: In this paper , the authors performed a retrospective observational study on patients hospitalised in 10 centers with a SARS-CoV-2 infection (Delta variant) from July to November 2021 by including all patients who had completed their primary vaccination at least 14 days before hospital admission and the same number of completely unvaccinated patients.
Journal ArticleDOI

Post-Vaccination Neutralization Responses to Omicron Sub-Variants

TL;DR: A large number of published and pre-print studies reporting sub-variant specific reductions in cross-neutralization compared to the prototype strain of SARS-CoV-2 raised concerns about the effectiveness of COVID-19 vaccines against infection and disease.
References
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Journal ArticleDOI

Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK.

Merryn Voysey, +81 more
- 09 Jan 2021 - 
TL;DR: ChAdOx1 nCoV-19 has an acceptable safety profile and has been found to be efficacious against symptomatic COVID-19 in this interim analysis of ongoing clinical trials.
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Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK.

Merryn Voysey, +81 more
- 09 Jan 2021 -