Duration of immune protection of SARS-CoV-2 natural infection against reinfection in Qatar

BACKGROUND The future of the SARS-CoV-2 pandemic hinges on virus evolution and duration of immune protection of natural infection against reinfection. We investigated duration of protection afforded by natural infection, the effect of viral immune evasion on duration of protection, and protection against severe reinfection, in Qatar, between February 28, 2020 and June 5, 2022. …

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Rates of COVID-19 Among Unvaccinated Adults With Prior COVID-19

Risk of SARS-CoV-2 reinfection among unvaccinated people with prior COVID-19 is a subject of debate.1,2 We performed a survival analysis in a large US population to assess the degree and duration of protection associated with natural immunity in unvaccinated individuals MethodsThis cohort study used data from patients tested for SARS-CoV-2 at 1300 sites of care …

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Risk of SARS-CoV-2 reinfection and COVID-19 hospitalisation in individuals with natural and hybrid immunity: a retrospective, total population cohort study in Sweden

Real-world evidence supporting vaccination against COVID-19 in individuals who have recovered from a previous SARS-CoV-2 infection is sparse. We aimed to investigate the long-term protection from a previous infection (natural immunity) and whether natural immunity plus vaccination (hybrid immunity) was associated with additional protection. MethodsIn this retrospective cohort study, we formed three cohorts using Swedish …

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Risk and severity of SARS-CoV-2 reinfections during 2020-2022 in Vojvodina, Serbia: a population-level study

AbstractBackground: Data on the rate and severity of reinfections with SARS-CoV-2 in real-world settings are scarce and the effects of booster vaccination on reinfection risk are unknown. Methods: In a retrospective cohort study, all SARS-CoV-2 laboratory-confirmed residents of Vojvodina, registered in the database of the Institute of Public Health of Vojvodina, between March 6, 2020 …

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Necessity of COVID-19 vaccination in previously infected individuals

The purpose of this study was to evaluate the necessity of COVID-19 vaccination in persons previously infected with SARS-CoV-2. Methods Employees of the Cleveland Clinic Health System working in Ohio on Dec 16, 2020, the day COVID-19 vaccination was started, were included. Any subject who tested positive for SARS-CoV-2 at least 42 days earlier was …

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