Evidence is mounting that having COVID-19 may not protect against getting infected again with some of the new variants. People also can get second infections with earlier versions of the coronavirus if they mounted a weak defense the first time, new research suggests. How long immunity lasts...

When Dr. Stanley Fineman started as an allergist in Atlanta, he told patients they should start taking their medications and prepare for the drippy, sneezy onslaught of pollen season around St. Patrick’s Day. That was about 40 years ago. Now he tells them to start around St. Valentine’s...

Iran said on Monday that it only cares about actions and not words, following remarks by US President Joe Biden that sanctions will not be lifted to bring Iran back to the negotiating table. When America returns to its commitments, "it can sit at this table again", said Iranian Foreign...

The United States announced plans Monday to reengage with the much-maligned U.N. Human Rights Council that former President Donald Trump withdrew from almost three years ago, as the Biden administration reverses another Trump-era move away from multilateral organizations and agreements....