This Is What Happens If You Only Get One Dose of the COVID Vaccine

By Kali Coleman

December 8, 2020

doctor in surgical mask giving male patient in mask a vaccine in arm — iStock

The race to a coronavirus vaccine is nearing the finish line, as the United States Food and Drug Administration (FDA) is set to review the Pfizer vaccine on Dec. 10. But the organization has already released some early documents ahead of this meeting, offering key information about the vaccine. In one document, the FDA revealed its findings on Pfizer's two-dose process: According to the organization, even one dose of this COVID vaccine offers people "some protection" against the coronavirus. Keep reading to find out more about the vaccine's efficacy, and for more on the vaccine, You Won't Be Able to Get the Pfizer COVID Vaccine in These 2 Places.

The FDA published a "Briefing Document" on Dec. 8 ahead of their planned meeting. In this document, the organization said that "based on the number of cases accumulated after Dose 1 and before Dose 2, there does seem to be some protection against COVID-19 disease following one dose" of the Pfizer vaccine, called BNT162b2.

However, the FDA notes that this data doesn't provide information about what happens with your protection long-term if you only receive one dose—which means the second dose is still extremely important. And long-term protection aside, the vaccine is only 52 percent effective after one dose. A week after receiving a second dose, that efficacy rises up to 95 percent.

"The efficacy observed after Dose 1 and before Dose 2 … cannot support a conclusion on the efficacy of a single dose of the vaccine, because the time of observation is limited by the fact that most of the participants received a second dose after three weeks. The trial did not have a single-dose arm to make an adequate comparison," the FDA document states.

It's worth noting that the increased protection afforded by a second dose does come with more adverse reactions. According to the FDA, the vaccine's side effects were more frequent after Dose 2 than after Dose 1. For the most common side effects experienced with the Pfizer vaccine, read on, and for more on coronavirus transmission, Dr. Fauci Says This One Thing Could Spread COVID More Than Anything Yet.

1

Injection site reactions

Older woman getting vaccinated — Shutterstock

Participants who had this side effect: 84.1 percent

And for more on the vaccine, The COVID Vaccine May Not Protect You From This One Thing, Experts Warn.

2

Fatigue

Shot of a mature man lying on his bed feeling exhausted — iStock

Participants who had this side effect: 62.9 percent

3

Headache

Woman waking up with headache — Shutterstock

Participants who had this side effect: 55.1 percent

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4

Muscle pain

young woman sitting on couch massaging sore neck — Shutterstock

Participants who had this side effect: 38.3 percent

5

Chills

Young man shivering under the blanket and drinking tea — iStock

Participants who had this side effect: 31.9 percent

And if you're worried about getting sick, Almost All COVID Transmission Is Happening in These 5 Places, Doctor Says.

6

Joint pain

Participants who had this side effect: 23.6 percent

7

Fever

man checking his temperature and making a phone call — Shutterstock

Participants who had this side effect: 14.2 percent

And for more on possible vaccine complications, These Are the COVID Vaccine Side Effects Doctors Are Worried About.

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