The drug from Merck and Ridgeback Biotherapeutics cut the risk of hospitalization or death among subjects by 50% in an early look at the study’s progress.

Safety scares, including deaths of several young study subjects, have set back efforts to bring more gene therapies to market, clouding one of biotech’s most promising technologies and hottest sectors.

Rapid tests are in high demand. Here’s what to know about doing them at home, how long results take and how accurate they are.

The Delta variant is finding clusters of unvaccinated people even in some of the best-vaccinated parts of the country.

Despite a high vaccination rate, the graduate school said dozens of breakthrough Covid-19 infections required a temporary return to remote learning.

Everything you need to know after the FDA expanded use of Pfizer’s Covid-19 vaccines to children 12 to 15 years.

Many parents and doctors had hoped the Pfizer-BioNTech vaccine would be available for 5- to-11-year-olds next month, but Pfizer must finish filing study data and complete its application to the FDA.

Learn mountaineering expert Bill Burke’s workout secrets to keep prospering physically in your 70s.

The CDC’s backing extra shots for some people, but not all, has left many with more questions than answers.

Columbia University professor Jeffrey Sachs says the task force’s ties to a nonprofit that worked with the Wuhan Institute of Virology risked a perception of bias.

Places with higher vaccination rates are keeping hospitalizations and deaths in check.

Questions and answers on issues such as how well boosters protect against the Delta variant and how effective they are.

CVS, Walgreens say people will self-identify as meeting qualifications for third shots.

The director of the Centers for Disease Control and Prevention said workers at high risk of Covid-19 infection should receive a booster of Pfizer’s vaccine, in a decision that deviated from the recommendation of an advisory panel that the CDC typically follows.

The extra Pfizer doses are rolling out to certain fully vaccinated adults, after disputes inside the U.S. government and with its scientific advisers.

Scientists are working to develop shots targeting the highly transmissible variant that has caused surges around the world. The mRNA platform behind some vaccines can make this process relatively straightforward.

The third dose of the vaccine was authorized for people who are 65 years or older or at high risk of severe Covid-19, including from their jobs.

A federal health official said there isn’t enough data to support giving a Pfizer booster dose to people who have received other Covid-19 vaccines.

Changing guidelines and the possibility of being given a placebo made the trial unappealing to some expectant mothers.

Medicare insurers drew $9.2 billion in federal payments in one year through controversial billing practices, with 20 insurers combining for more than half of the total, according to federal health investigators.