What to expect after a Covid-19 vaccine, from how long side effects last to when protection kicks in

Covid-19 shots from Pfizer and Moderna can carry side effects for a few days. They offer...

10 people in the US had bad allergic reactions to Moderna’s vaccine – after 4 million doses

Your odds of having an allergic reaction in the minutes after receiving Moderna's vaccine...

Claims of 'US variant' of the coronavirus baseless, says CDC

A White House report suggests a "USA variant" may be responsible for the recent...

Why you're not fully protected from Covid-19 after a single vaccine dose

Most Covid-19 vaccines are split into 2 doses. Only after the second will you be up to...

The 11 most mind-blowing, awe-inspiring health discoveries and innovations of 2020

Not everything was awful this year. Here are 2020's most impressive feats of health, from...

One striking chart shows just how well Pfizer's shot works to prevent Covid-19 infections

Two weeks after the first shot, people who received Pfizer's Covid-19 vaccine showed...

Quarantining is based on 700-year-old virus-fighting logic

14-day coronavirus quarantines were too long for many people to handle. Turns out, most...

Sweden's prince and princess have Covid, as their country struggles with a devastating second wave

Prince Carl Philip and Princess Sophia are isolating at home with flu-like symptoms. They...