Summary: As the rollout of the Johnson & Johnson and AstraZeneca COVID-19 vaccines face hurdles around the world, we take a look at the science behind the shots and the risk of "extremely rare" blood clots.
Summary: As the rollout of the Johnson & Johnson and AstraZeneca COVID-19 vaccines face hurdles around the world, we take a look at the science behind the shots and the risk of "extremely rare" blood clots.