Vaccinated people who were infected by the earlier Omicron subvariants have four times greater protection than vaccinated people who were not infected against the new variants like BA.5, finds a new study, published in the New England Journal of Medicine journal.

For the study, the team accessed the registry of Covid-19 cases at Portugal's national level. The research indicates that previous infection in vaccinated people (the so-called hybrid immunity) continues to confer immunity for the variants that are known for their ability to evade the immune response.