It was already known that previous illness with Covid-19 does not permanently protect against reinfection. Therefore, health authorities in the USA, Europe, and England advise those who have recovered to refresh their immunity.
Two recent studies now show a significant decrease in reinfection rates when natural immunity is boosted by a vaccine, the New England Journal of Medicine reports.
Israeli epidemiologists evaluated data from 149,032 patients infected during Israel’s first two waves of disease. Of these, 83,356 Israelis had responded to a call from the Ministry of Health and had been vaccinated with Biontech/Pfizer between 100 and 190 days after their infection.
Only 354 became reinfected with SARS-CoV-2 in the delta wave: an incidence of 2.46 cases per 100,000 person-days. Among the 65,676 nonvaccinated recovered persons, 2,168 infections occurred: This corresponds to an incidence of 10.21/100,000 person-days – four times higher.
For a British study, more than 35,000 asymptomatic healthcare workers were tested twice weekly by PCR from December 2020 to September 2021.
About 9,000 of them were already infected with Covid-19 before the study began: With one or two subsequent vaccinations (almost all with Biontech), protection against reinfection increased several-fold – with no signs of waning protection during the study period.
- source: kurier.at/picture: pixabay.com
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