Covid vaccines give extra protection to previously infected, studies show | Coronavirus

Covid-19 vaccines provide significant extra protection for people who have already been infected, according to two new studies.

The jabs have proven highly effective in protecting those who have never had Covid, but their effectiveness at preventing symptoms and severe outcomes in people who have previously been infected has, until recently, been less clear.

Now two separate pieces of research, published in the Lancet Infectious Diseases journal, confirm that Covid-19 vaccines provide additional protection for people who have already been infected with Sars-CoV-2 – especially against severe disease.

In the first study, conducted in Brazil, researchers found that four vaccines – CoronaVac, Oxford/AstraZeneca, Janssen and Pfizer/BioNTech – provide extra protection against symptomatic reinfection and severe outcomes such as hospitalization and death in people who had previously caught coronavirus.

The second study, from Sweden, found that vaccination against Covid-19 provided additional protection to those who had had Covid before, for at least nine months.

Together, the studies provide crucial data on vaccine effectiveness in people with a prior infection and underline the benefits of getting vaccinated regardless of whether someone has had Covid. Experts say the findings could also help inform global vaccine strategies.

“Covid-19 vaccines have been proven to be highly effective at preventing symptomatic infection and hospitalisation among those with no prior infection but effectiveness for those with prior infection is less clear,” said the author of the first study, Julio Croda, of Universidade Federal of Mato Grosso do Sul and Foundation.