How does the Delta variant dodge the immune system? Scientists find clues.
One dose of vaccine is not enough to protect against the Delta and Beta variants, new research suggests, and even people who have had Covid-19 should be immunized.
Another US Covid-19 surge may look different, experts say, particularly for younger people. Here's how
Experts say Covid-19 vaccinations in the United States are going extremely well -- but more people need to be protected and the country may be at the start of another surge.