What’s next for Pfizer’s COVID-19 vaccine after UK rollout

Britain began the mass-vaccination of its population against COVID-19 on Tuesday, becoming the first Western nation to do so in a global endeavour that poses one of the biggest logistical challenges in peacetime history.

Margaret Keenan, a 90-year-old grandmother from Britain, became the first person in the world to receive the Pfizer vaccine outside of a trial following its rapid clinical approval on Dec. 2.

Pfizer said in November final results from the late-stage trial of its COVID-19 vaccine showed it was 95