Some countries are moving ahead with plans to offer a fourth dose of COVID-19 vaccine. But studies are raising questions about the potential advantages of this extra booster.

Researchers in South Africa have found that people infected with omicron, on average, are less likely to end up in the hospital. But the variant may act differently here in the U.S.

This animated video uses puzzle pieces to show how a coronavirus binds to a cell's surface — and what happens when a mutation occurs.

On an eight-hour Emirates flight, with mask-wearing enforced, a whopping 27 coronavirus-positive people boarded the plane in Dubai. Guess how many passengers got infected?

The conventional wisdom is that it takes 15 minutes of close contact to a contagious person to put you at risk. But even a short exposure could prove problematic.