After vaccination, antibody levels can help predict how much protection a COVID-19 shot offers, scientists are learning. The finding could speed up the development of future vaccines.

An analysis of blood from people who had received the Johnson & Johnson COVID-19 vaccine found a lower level of neutralizing antibodies against viral variants but a strong response involving T cells.

For most people, COVID-19 vaccines promise a return to something akin to normal life. But for the hundreds of thousands of Americans who have a transplanted organ, it's a different story.

Scientists say the pandemic will only end in the U.S. when we achieve what's called herd immunity. Play with our simulations to see how immunity can stop an outbreak in its tracks.

First, can someone who has been vaccinated still spread the disease? Second, will the vaccine remain effective as the virus itself evolves? And third, how long will the vaccine's protection last?

Science writer Robin Marantz Henig has written about dangerous emerging pathogens for 30 years. But none of what she learned could shed light on her own confusing encounter with this virus.

Researchers found that a class of antibodies in a monkey's blood provides protection from COVID-19. If that hold true for humans, a blood test may predict whether a vaccine candidate is working.

There's a lot that scientists don't know about how viral infections can interact. But researchers are eager to figure out how coronavirus infections might affect flu infections and vice versa.

A vaccine against the coronavirus needs to keep people from getting very sick and dying. But preventing the spread of the disease is also important, and vaccines delivered by nasal spray may do that.

Recent studies have raised fears that immunity to the coronavirus might be fleeting, thus making potential vaccines ineffective. The reality of the science is more complex — and more reassuring.