New Covid Variants Are Circulating. Here’s What to Know. The “nightmare variant” is not as bad as it sounds.
U.S. Health Officials Urge Vigilance as Ebola Spreads in Uganda There are no cases in the United States, but the C.D.C. wants doctors to be on the alert for patients with telltale symptoms.
Setting the Record Straight on Covid Variants and Reinfections There has yet to be a variant the negates the benefits of vaccines.
A Better Way to Measure Immunity in Children Some scientists believe that a clearer picture of Covid vaccine efficacy could have emerged sooner if investigators had tracked certain immune cells, not just antibodies.