Intended for healthcare professionals


Covid-19: FDA authorizes Moderna vaccine as US starts vaccinating health workers

BMJ 2020; 371 doi: (Published 21 December 2020) Cite this as: BMJ 2020;371:m4924

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  1. Janice Hopkins Tanne
  1. New York

The US Food and Drug Administration (FDA) authorized the Moderna vaccine against covid-19 for emergency use on 18 December, with the US on track to receive 20 million doses by the end of this month and a further 85-100 million doses in the first three months of 2021.1

The move follows the authorization of the Pfizer-BioNTech vaccine for emergency use a week ago. Both vaccines are said to have around 95% efficacy. Pfizer and Moderna have said that they will apply to the FDA for full licensure. Vaccines from other makers are expected in early 2021.

Infections and deaths increase in the US every day. As of 20 December it recorded 193 947 new cases, 2628 new deaths, and 113 929 people hospitalized. The past week has seen an average of 216 705 new cases a day. The US has so far had 17.8 million cases, by far the highest number in the world.2 Hospitals in several states have said that they are running out of intensive care unit beds.

Gustave Perna, head of the US government’s Operation Warp Speed, which is in charge of distributing the vaccines, apologized for some states receiving smaller doses of the Pfizer vaccine than expected, blaming manufacturing problems.3 Other reports said that the Pfizer vials had more doses than expected and thus were capable of immunizing more people.4

Building confidence

Two vaccines will now be available to many of the 21 million frontline healthcare workers in the US. Next in line will be staff and residents at age care homes. A Centers for Disease Control and Prevention (CDC) panel voted on 20 December that next in line should be “frontline essential workers” and people over 75.5

The first person to receive the vaccine was Sandra Lindsay, director of critical care nursing at Long Island Jewish Health Center in New York City, an area hard hit at the beginning of the pandemic in the US. Lindsay, who is Black, received the injection from Michelle Chester, a Black physician at the hospital. This photo-op was an attempt to build confidence for the vaccines in the Black community, where there is much distrust of the medical establishment.6

Senior US government officials have already received the first dose of the Pfizer vaccine: Nancy Pelosi, speaker of the House; Mitch McConnell, Senate majority leader; Vice President Mike Pence and his wife, Karen Pence; and the US surgeon general, Jerome Adams. President elect Joe Biden and his wife, Jill Biden, will receive injections on 21 December.

President Donald Trump has neither received the vaccine nor made a statement about vaccine distribution.

Side effects

Both Moderna’s and Pfizer-BioNTech’s vaccines use the new messenger RNA (mRNA) technology, but Moderna’s vaccine can be kept cold in an ordinary freezer, whereas the Pfizer-BioNTech vaccine must be kept at –70°C.

Both vaccines require two injections: 21 days apart for the Pfizer vaccine and 28 days apart for the Moderna vaccine. Side effects have been reported with both: pain at the injection site, muscle aches and pains, and sometimes a slight fever.

A few anaphylactic reactions have been reported with the Pfizer-BioNTech vaccine in the UK and the US. The UK now advises that people with any history of anaphylactic reactions should not receive the vaccine. The CDC says that people who have had an allergic reaction to an ingredient in the vaccines should not receive the vaccine, while people who have not had allergic reactions to injectable vaccines but have had allergic reactions to food, pets, or medicines—but not anaphylactic reactions—may receive it.

All who receive the vaccine should be monitored for 15 to 30 minutes after injection.7


  • Correction: On 22 December 2020 we corrected the headline to “FDA authorizes Moderna vaccine” (not “approves”).

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