Covid vaccines fight off infections but less effective against delta: Study

Results from UK survey are likely to fuel calls to give booster shots to the fully vaccinated.

Vaccines against Covid-19 are less effective against the delta variant, a large U.K. study showed in results that may fuel a push for booster shots for fully vaccinated people.

Pfizer Inc. and BioNTech SE’s messenger RNA vaccine lost effectiveness in the first 90 days after full vaccination, though that shot and the one made by AstraZeneca Plc still staved off a majority of Covid infections. When vaccinated people did get infected with delta, they had similar levels of virus in their bodies as those who hadn’t had their shots, backing up a recent assessment by the Centers for Disease Control