Three jabs best for preventing Covid infections, global analysis finds

Number of doses, not vaccine combinations, key to boosting immunity, according to largest study of its kind

Three doses of the same Covid-19 vaccine or a combination of jabs work equally well in preventing infections, according to the largest study of its kind.

While the effectiveness of individual coronavirus vaccines is well known, the evidence around combinations of jabs has been less clear, especially for particular groups such as older people and those who are immunocompromised.