Pfizer's COVID-19 vaccine was the first to be OK'd for emergency use by the U.S. Food and Drug Administration (FDA) last year. And millions of people have received it safely so far.
Here are some important questions and answers about this vaccine. (See information about the Moderna and Johnson & Johnson vaccines.)
Q. How does the vaccine work?
A. The Pfizer vaccine contains genetic material called messenger RNA (mRNA). This small piece of the coronavirus's mRNA orders the cells in your body to make copies of a distinctive but harmless spike protein that appears on the surface of the coronavirus. These spike proteins trigger an immune reaction. Your body creates antibodies, which then protect you from getting sick if you're exposed to the real virus later.
It's important to note that the vaccine doesn't contain the real coronavirus. So getting the vaccine cannot give you COVID-19.
Q. How many shots are given and how far apart?
A. This vaccine requires two shots given three weeks apart.
Q. How long after getting your shots does it take to be effective?
A. According to the Centers for Disease Control and Prevention (CDC), it usually takes a few weeks for immunity to develop after any vaccine. Trial data suggest that this vaccine starts to offer some protection within two weeks of the first shot. But you won’t be considered fully immunized until two weeks after your second shot.
Q. How effective was the vaccine in clinical trials?
A. The vaccine was 95% effective in preventing COVID-19 in clinical trials. That's very good. FDA's benchmark was an efficacy rate of 50%.