The country's first coronavirus shots are one step closer to getting injected into the general public after the Food and Drug Administration (FDA) granted emergency authorization late Friday to the vaccine manufactured by Pfizer and BioNTech.
The announcement comes as the country is reeling from a new surge of COVID-19 infections, with deaths now exceeding 3,000 people each day.
Now that the FDA has given the vaccine the green light, the federal government is able to start distributing it to states. However, vaccinations won't begin until after a Centers for Disease Control and Prevention (CDC) committee recommends the vaccine and the CDC accepts that recommendation.
The CDC panel is expected to meet soon to vote on whether to recommend the vaccine and for which groups.
For example, the vaccine has not been studied in children younger than 16 years old, or women who are pregnant or breastfeeding.
Once that decision occurs, vaccinations can begin. Health and Human Services Secretary Alex Azar said on ABC News Friday that vaccinations could come as early as Monday or Tuesday.
Earlier this month, the same CDC vaccine panel recommended that the first doses should be administered to health workers as well as residents and staff of long-term care facilities.
However, each state can make its own decisions about whom to prioritize and where to administer the vaccines. The decisions are complicated by the vaccine's logistical challenges, including the extreme cold storage temperatures it requires.
Initial doses will be also extremely limited.
"The fact is vaccines are not going to have a public health impact for at least several months,” Anthony Fauci, the government’s top infectious diseases expert, said Friday on a webcast hosted by the Journal of the American Medical Association.
The Trump administration's Operation Warp Speed expects to ship 2.9 million doses to states within 24 hours of authorization, but even under perfect conditions, the general population likely won't get vaccinated until late spring or summer 2021. Until then, health officials are warning everyone that the coming months will be dire.
The vaccine is intended to be administered in two doses given three weeks apart, and officials said they intend to hold back the second dose and ship it to states separately to ensure there's no waste.
One potential area of concern that's arisen among CDC and FDA officials is the possibility of allergic reactions. The U.K. began vaccinating people this week, and there were reports of people experiencing serious allergic reactions almost immediately after receiving the vaccine.
The U.K.’s National Health Service on Tuesday said people with a significant history of allergies shouldn’t receive the shot.
During a presentation to an FDA advisory panel Thursday, Pfizer representatives said they were unaware of any instances of allergic reactions during the clinical trial.
Still, the issue of allergic reactions led the CDC to convene a meeting of experts on Thursday night, after the FDA panel voted 17-4 in favor of recommending authorization.
The CDC and FDA are also working out the right instructions for doctors that will need to go on the vaccine's label, but it's not expected to be a major roadblock.
Clinical trials endorsed by the FDA have shown the vaccine to be 95 percent effective at preventing infection with no severe side effects.
The authorization is occurring under a political cloud, as President Trump and White House Chief of Staff Mark Meadows have repeatedly pressed the agency to move quicker.
The authorization is short of a full approval; Pfizer would have to file a separate application for full FDA approval for its vaccine. Meanwhile, clinical trials are still ongoing and company representatives intend to monitor trial subjects for two years in order to study the full effects of the vaccine.