When the first monkeypox cases were identified in early May, European health officials were stumped. The virus was not known to spread easily among people, let alone infect dozens — and soon hundreds — of young men. The origins of the outbreak are now becoming clearer. Genetic analysis suggests thatContinue Reading

Wading into an acrimonious debate over booster doses, researchers in Israel reported on Wednesday that a third dose of the Pfizer-BioNTech coronavirus vaccine can prevent both infections and severe illness in adults older than 60 for at least 12 days. The study, published in the New England Journal of Medicine,Continue Reading

While the spread of new coronavirus cases is steady or slowing in many parts of the world, it is accelerating in the Western Hemisphere, where new case reports rose by 20 percent in the past week, the World Health Organization warned on Wednesday. North America, where new case reports areContinue Reading

Officials at the Centers for Disease Control and Prevention on Friday pushed back against the idea that the monkeypox virus can spread through the air, saying the virus is usually transmitted through direct physical contact with sores or contaminated materials from a patient. The virus may also be transmitted byContinue Reading

The three sizable urban centers in the United States where the coronavirus is spreading fastest right now have something in common: They are major warm-weather tourist destinations. Miami-Dade County, Fla., Honolulu County, Hawaii, and San Juan, P.R., are all averaging at least 85 new cases a day per 100,000 residents,Continue Reading

Alameda County, the San Francisco Bay Area’s second-most populous county, reinstated on Friday a mask mandate in most indoor spaces, which it had dropped in February. Officials cited growing hospitalizations in Alameda, whose county seat is Oakland, which are up about 35 percent over the last two weeks to aContinue Reading

Russia controls a fifth of Ukraine President Volodymyr Zelensky said Russian forces had seized 20 percent of Ukraine’s territory as the war nears its 100th day. He said that Russia had expanded its control of Ukrainian territory from an area roughly the size of the Netherlands before the invasion toContinue Reading

Coronavirus infections surged in South Africa in recent months despite research suggesting that about 98 percent of the population had some antibodies from vaccination, previous infection, or both. The study, released Thursday but not yet peer reviewed, analyzed the prevalence of two types of antibodies in 3,395 blood donors collectedContinue Reading

Covid cases and hospitalizations are rising again in the U.S., and deaths are starting to rise, too. In response, many people are understandably asking what the country can do to minimize the virus’s toll in the weeks ahead. So far, a lot of discussion has focused on mask mandates. SchoolsContinue Reading

After the Sept. 11 attacks, the United States considered immunizing the entire population to protect against a terrorist attack using smallpox. “In the end, it was decided no, because of the negative consequences of vaccinating lots of people,” Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of PublicContinue Reading