Vaccinating pregnant women against influenza whenever the opportunity arises could be a simple and effective strategy for areas with year-round flu transmission, a study in JAMA Network Open suggests.

The retrospective cohort study took place in Singapore, which has year-round flu transmission because of its tropical climate, said the authors led by the country’s Communicable Diseases Agency.

They said Singapore typically updates recommended vaccine composition twice yearly, when both Northern and Southern Hemisphere flu seasons start.

The study tracked 220,000 infants born from 2017 to 2024 — including 26% whose mothers were vaccinated against flu — until flu hospitalisation, death or age six months.