Booster shot of Pfizer Covid jab increases protection to over 90%, new study finds

A booster shot of the Pfizer vaccine gives over 90% protection against symptomatic Covid-19 regardless of which vaccine was used first, a British study has found.

The study, led by the UK Health Security Agency and published on Monday, examined the effectiveness of this booster for over-50s who had received AstraZeneca or Pfizer as their first shots.