Findings from Brazil, Sweden and the United Kingdom show that before the advent of Omicron, vaccination benefited even those who had had a bout of COVID-19.

Even people who have had COVID-19 receive long-lasting benefits from a full course of vaccination, according to three recent studies¹^–³. What's more, one of the studies³ found that the ‘hybrid’ immunity caused by vaccination and infection is long-lasting, conferring highly effective protection against symptomatic disease for at least six to eight months after vaccination.

The data were collected before the Omicron variant emerged, casting some doubt on the studies’ relevance today. But if the findings hold up, they could inform vaccination schemes and vaccine passports, which some countries require for entry to places such as restaurants. The work also counters high-profile claims that people who have had COVID-19 don’t benefit from vaccination.

Just such a claim helped to launch some of the research. Brazilian President Jair Bolsonaro “said that he already had COVID-19, and for this reason, it is not necessary to take a vaccination”, says Julio Croda, an infectious-disease doctor and epidemiologist at the Oswaldo Cruz Foundation in Rio de Janeiro, Brazil. Croda and his colleagues drew on Brazilian vaccination and infection databases to test such assertions.

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