I Covid vaccines provide extra protection for those recovered from Sars-CoV-2 infection, especially against serious illness. But in general it appears that these people who have combined immunity (natural-induced shield injection) are also at a lower risk of reinfection. This is what emerges from two new studies published in ‘The Lancet Infectious Diseases’.
In the first work, conducted in Brazil, the researchers found that four vaccines – CoronaVac, Oxford-AstraZeneca (ChAdOx1), Janssen (Ad26.COV2.S) and Pfizer-BioNTech (BNT162b2) – provide additional protection against symptomatic reinfection ( 39% for CoronaVac, 56% for AstraZeneca, 44% for Janssen, 65% for Pfizer-BioNTech) and against severe outcomes, hospitalization and death (81% for CoronaVac, 90% for Oxford-AstraZeneca, 58% for Janssen and 90 % for Pfizer-BioNTech) in people who have already had a Sars-CoV-2 infection. The study did not include cases of reinfection from Omicron variants.
A second research, conducted in Sweden, found that the first three months following Sars-CoV-2 infection were associated with higher mortality than in people who had not had the infection, but patients recovered. they had a lower risk of reinfection for up to 20 months. Vaccination provided additional protection for the recovered for at least 9 months.
Importantly, however, the study only followed people until October 2021, so it did not include any analyzes of reinfection from Omicron variants. For this reason, experts point out that more research is needed to understand the impact of new variants, including Omicron with its ability to evade immunity.