Agency officials said reducing the number of doses creates a potential for harm in patients because "they may assume that they are fully protected when they are not" and may "take unnecessary risks."

The top military official with the federal vaccine effort spoke less than 24 hours after Moderna's COVID-19 vaccine became the second to receive an emergency use authorization from the FDA.

The Food and Drug Administration greenlights the biotech firm's vaccine for emergency use in the U.S. The move bolsters a vast inoculation effort that's already underway.

Advisers to the Food and Drug Administration voted 20-0 to recommend that the agency authorize Moderna's vaccine for emergency use during the pandemic. There was a single abstention.

Despite being founded a decade ago, Moderna has never had a product make it to market. And the company registered its first factory with the Food and Drug Administration just this week.

Two days before a panel of experts is set to review Moderna's COVID-19 vaccine and advise the Food and Drug Administration, documents show the vaccine is 94% effective and well-tolerated.

States are starting to administer their first doses of Pfizer's newly FDA-authorized COVID-19 vaccine. It marks a new phase in the pandemic, but what's that mean for you?

The power of family history can lead a person to do a lot of things. For Howard Berkes, the family tradition of facing crises head-on led him to sign up for experimental testing of a COVID-19 vaccine.

In the U.S., front-line health care workers are likely first in line to get immunized with a COVID-19 vaccine, once the FDA says yes. But what about the rest of us? Here's what we know so far.

As FDA emergency use authorization of Pfizer and Moderna vaccines nears, airlines, FedEx and UPS prepare to transport millions of vials of life saving shots.

Experts say low-risk people in the U.S. will likely be immunized before many high-risk people in poor countries.

One of the two leading vaccine candidates requires deep, deep freezing. Here's how communities are working to solve for this and how the new Moderna vaccine could help.

The vaccine is nearly 95% effective in preventing illness, according to an interim analysis of a clinical test involving 30,000 people.

Several COVID-19 vaccine candidates are being tested now. But why does it take 30,000 volunteers to know if one is safe and effective? And what does it mean to say a vaccine candidate is working?

Moderna is currently developing a promising, yet still unproven, vaccine against the coronavirus. But Moderna executives have already sold tens of millions of dollars worth of stock in the company.