The US just authorized a 3rd coronavirus shot, adding a convenient, single-dose option to boost the rollout

• The FDA just authorized Johnson & Johnson’s single-dose coronavirus vaccine.
• The decision comes after a panel of independent experts voted unanimously on Friday in favor of recommending the shot. 
• J&J has said it will be ship nearly 4 million doses immediately following a regulatory OK. 
• Visit the Business section of Insider for more stories.

The US vaccination campaign received another jolt of good news, with US regulators on Saturday authorizing a third coronavirus vaccine for emergency use. 

This single-dose vaccine, developed by the healthcare giant Johnson & Johnson, was found to be and safe and effective in a massive clinical trial. J&J expects to quickly deliver nearly 4 million doses to the US, and they’ll be made available to individuals for free. 

The authorization, which the FDA announced in a statement, comes after an expert panel on Friday voted unanimously in favor of the shot. The FDA said J&J’s vaccine can be given to adults over age 18.

With three authorized vaccines, the US is on the precipice of enjoying a surge in supply in the coming weeks. By the end of June, according to drugmakers’ projections, the US should have enough doses to immunize 300 million people. 

A vaccine that’s easier to store and administer

J&J’s vaccine should bring some much-needed simplicity to a chaotic nationwide rollout. It’s a single-dose immunization and can be kept stable for months at standard refrigerator temperatures. The other authorized vaccines in the US require two shots, several weeks apart.

A 40,000-person trial found that J&J’s shot was safe and 66% effective at preventing moderate-to-severe COVID-19.

The first two US-authorized vaccines demonstrated 94% and 95% efficacy at preventing symptomatic cases of COVID-19, though experts caution against comparing those figures directly.

J&J has emphasized its vaccine’s ability to prevent the worst outcomes of COVID-19.

Starting two weeks after receiving an injection in the study, 31 people were hospitalized with COVID-19: 29 had received the placebo shot and just two had gotten J&J’s vaccine. The study also tallied seven deaths from COVID-19 – all in the placebo group.

Already, more than 47 million Americans have received at least one dose of a vaccine, according to the Centers for Disease Control and Prevention.

The accelerating immunization campaign is one reason to be optimistic about the state of the pandemic, doctors and scientists told Insider. They said they think that by summer, it’ll be safe to see extended family and to plan outdoor vacations.

On the other hand, coronavirus variants, some of which may diminish the power of vaccines, could bring a surge in cases. And we’ll need to overcome some individuals’ hesitancy to get a shot.