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. 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. Participants who had this side effect: 62.9 percent Participants who had this side effect: 55.1 percentae0fcc31ae342fd3a1346ebb1f342fcb And for more up-to-date information, sign up for our daily newsletter. Participants who had this side effect: 38.3 percent 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. Participants who had this side effect: 23.6 percent 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.