COVID-19 vaccine FAQ: Here's everything you need to know

COVID-19 vaccines offer hope for getting out of the pandemic. They also raise a lot of questions. Here are some answers.

Are they safe? What are the side effects?

Both vaccines authorized in the United States, from Pfizer and Moderna, have been found to be safe after intensive reviews by the Food and Drug Administration (FDA).


Experts looked at safety data from about 30,000 people who participated in the clinical trials for each vaccine, and now millions more people have gotten the vaccines. Serious side effects have been extremely rare and have so far consisted of severe allergic reactions in a few people. The rate of severe allergic reactions is about 4.5 per 1 million shots administered, according to Centers for Disease Control and Prevention (CDC) data. And allergic reactions can be treated.

“If this occurs, vaccination providers have medicines available to effectively and immediately treat the reaction,” the CDC notes.

Mild reactions that go away in a few days are more common. Those include pain at the injection site, fatigue, headache and chills. The CDC even has a smartphone app to help track reactions.

How well do they work?

Both the Pfizer and Moderna vaccines have been found to work extremely well, above the previous guesses of many experts. Both vaccines were about 95 percent effective in preventing people from getting COVID-19 in clinical trials.

Does it cost money to get the vaccine?

No. It is free, even if you don’t have health insurance.


Which vaccine should I get? Is one better than others?

Both the Pfizer and Moderna vaccines work extremely well, and experts say people should get whichever happens to be available at a particular site.

The choices might get a bit more complicated when and if additional vaccines are authorized. Johnson & Johnson, for example, has applied to the FDA and could be authorized later this month or early in March.

That vaccine was 66 percent effective overall, a lower level, but still above the FDA’s minimum of 50 percent.

Still, Ashish Jha, dean of the Brown University School of Public Health, wrote in The Washington Post that Johnson & Johnson is 100 percent effective in what really matters: preventing hospitalizations and deaths.

“If you are able to get a vaccine — any vaccine — get it,” he wrote.

How long after getting vaccinated will I be protected? And how long does it last?

The Centers for Disease Control and Prevention says it can take up to two weeks following the second dose to get full protection. Both the Pfizer and Moderna vaccines require two doses. Still, some protection can build even after the first dose.

It is unclear how long the protection will last. It is possible a booster shot will be necessary in future years. Researchers need more time to continue following study participants to see if the protection from the vaccine continues or wears off over time.

Do I still need to wear a mask and take precautions after vaccination?

The CDC advises that, yes, you still do. Why? Because while the vaccines are very effective in preventing you from getting sick, there is less evidence on whether you can still transmit the virus on to someone else, meaning wearing a mask and maintaining distance from others is still important until a higher percentage of people are vaccinated.

The good news is that early evidence indicates the vaccine does cut transmission of the virus to other people as well.

Anthony FauciAnthony FauciFauci: Whatever COVID-19 vaccine is available, 'take it' Julia Roberts presents Award of Courage to Fauci: 'You have been a beacon for us' The Hill's Morning Report - Presented by The AIDS Institute - Ahead: One-shot vax, easing restrictions, fiscal help MORE, the government’s top infectious diseases expert, said at a briefing that there are now “some studies that are pointing into a very favorable direction” for vaccinations cutting transmission.

Also, the CDC says that if you are fully vaccinated, you do not need to quarantine if you are exposed to the virus.


When can I get vaccinated? Where do I go?

Eligibility for the vaccine is determined by each state, though there are recommendations from the federal government.

Vaccinations largely started with health care workers and people in nursing homes. Now, they have progressed in many places to categories such as people over 65 and essential workers. The average person not in those categories is not yet eligible.

It is unclear exactly when everyone will be eligible, but it is expected to be sometime in the spring. Even then, it will still take some time once the doors are open to everyone for everyone to actually be able to book an appointment and get a shot in the arm.

How to sign up also depends on your state and location. There are multiple avenues, including pharmacies such as CVS, other health care providers and mass vaccination sites such as sports stadiums.

Check your local or state health department website for more information.

How does the vaccine work?


Both the Pfizer and Moderna vaccines are mRNA vaccines, a new technology. The mRNA vaccine provides genetic code for the body to make part of the coronavirus, called a spike protein, which the virus uses to enter cells. The body then triggers an immune response to these spike proteins, teaching it how to fight the virus.

It is impossible for the vaccine to give you the coronavirus, since the vaccine does not contain the virus, and it also does not alter your DNA in any way.

Were the vaccines rushed?

The vaccines were developed in record time given that the process usually takes multiple years. But the speed was not due to cutting corners. The Pfizer and Moderna vaccines both went through three stages of clinical trials, with roughly 30,000 people each in the phase 3 trials, and a full FDA review process with a public hearing of an advisory panel of experts. The speed was helped along by the urgency of the crisis, meaning ample funds were available, including from the government, and because the companies started manufacturing doses even before the trials were complete.

Do the vaccines still work against the new variants of the virus?

New, more contagious variants of the virus are causing concern and leading to spikes in cases in some countries. The good news is that the current vaccines have been shown to work well against one of the most prevalent variants, first found in the United Kingdom.

Experts are more concerned about a variant first identified in South Africa. That variant has been shown in studies to reduce the level of antibodies the vaccines produce to fight the virus, though exactly how much that will reduce effectiveness is still unclear for the Pfizer and Moderna vaccines.


Moderna said in late January that although there was a drop in antibody levels, they are still “above levels that are expected to be protective.”

The vaccines still offer protection, particularly on the most important aspect: preventing severe disease that can hospitalize or kill you, Fauci said on MSNBC.

“There is enough cushion in the efficacy of the vaccine that there is still some protection, particularly against serious disease,” he said.

It is not yet clear if the Pfizer and Moderna vaccines will need to be updated for the new variant, but the companies are working on that possibility.

What happens if I miss the second dose?

The Pfizer vaccine is intended to have a second dose 21 days after the first dose, and the Moderna vaccine has a second dose 28 days later. But don’t panic if you miss that exact day. You should still get a second dose, but the CDC says that while it is best to get it on schedule, you can get it up to 6 weeks after the first dose if you miss the window.

Can kids get the vaccine?

Not yet. The Pfizer and Moderna vaccines are currently authorized only for ages 16 and up and 18 and up, respectively. Additional studies are needed in kids. According to Fauci, data on children ages 12 to 17 is expected sometime in the fall, but data on children younger than that is not expected until the first quarter of next year.

Should I get the vaccine if I have allergies?

Yes. The FDA is advising people to avoid the vaccine only if they are allergic to an ingredient of the vaccine. (Ingredients are listed here and here.)

Should I get the vaccine if I’m pregnant?

The CDC says pregnant women can get the vaccines, though they may want to discuss the issue with their doctor. “Experts believe [the vaccines] are unlikely to pose a specific risk for people who are pregnant,” the CDC states. “However, the actual risks of mRNA vaccines to the pregnant person and her fetus are unknown because these vaccines have not been studied in pregnant women.”

Should I get the vaccine if I already had COVID-19?

The CDC says you should. That’s because it is unclear how long immunity from having had the virus lasts. Some studies suggest that only one vaccine shot may be needed for people who have already had the virus since the vaccine helps boost the preexisting level of protection.