Woman wearing a mask with a germ in the background

Coronavirus (COVID-19) Vaccines

A vaccine is a major component of preventing COVID-19. In an unprecedented effort to curb the pandemic, scientists from around the world have come together to condense a 10-year research and development timeline into roughly 10 months. There are over 200 vaccines in development, and dozens are in clinical trials. In the United States, three vaccines have received emergency use authorization from the Food and Drug Administration (FDA). Of those three, two—the Pfizer-BioNTech vaccine and the Moderna vaccine—have received full approval from the FDA.

To move at such a rapid pace, researchers explored new vaccine platforms, like mRNA. Manufacturers produced batches of vaccines without waiting for final clinical trial results in order to have them immediately ready if proven safe and effective. In spite of the speed, safeguards like data and safety monitoring boards remained in place throughout the process. A vaccine is only FDA-authorized once it is proven to be safe. 

Learn the Basics of Getting Vaccinated

Frequently Asked Questions

  • Which vaccines are currently available?

    In the U.S., there are currently three available vaccines. The FDA has granted full approval to the Pfizer-BioNtech vaccine, the Moderna vaccine, and emergency use authorization to the Johnson & Johnson vaccine. There are large-scale Phase 3 clinical trials in progress or being planned for two additional COVID-19 vaccines in the U.S.: AstraZeneca’s vaccine and Novavax’s vaccine​.

  • Are the COVID-19 vaccines safe?

    The available COVID-19 vaccines underwent extensive safety and regulatory processes. In order for the vaccines to receive FDA emergency use authorization, each clinical trial was subjected to review from a panel of scientists who are independent of the companies developing the vaccines. These scientists are members of data and safety monitoring boards (DSMB) that review clinical trials of drugs and vaccines. DSMBs have vetted drugs and vaccines for decades.

  • When can I get the COVID-19 vaccine?

    Everyone 12 and older across the U.S. is now eligible to be vaccinated. Appointments, including walk-in appointments, are now readily available nationwide.

  • How do I sign up to get vaccinated?

    The best place to start is with a healthcare provider. Vaccines are being distributed locally and you may be able to walk in or secure appointments at a local clinic. You can also search for pharmacies and providers that offer vaccination on Vaccines.gov.

  • What are the side effects of the COVID-19 vaccine?

    Public health officials say to expect largely mild side effects. You may feel pain and redness at the injection site, fatigue, a headache, joint and muscle aches, and/or a fever. Some less common side effects can include swollen lymph nodes (especially in the armpit) and swelling at the injection site. A very rare symptom may include a temporary weakness or paralysis of the facial muscles called Bell’s Palsy. In extremely rare cases, some people who received the Johnson & Johnson vaccine developed a blood clot called cerebral venous sinus thrombosis.

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

    Even if you’ve previously been infected with COVID-19 and recovered, experts recommend getting vaccinated. Your natural immune response may not be strong enough to protect you from future infections. If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, you should wait 90 days before getting a COVID-19 vaccine, according to the CDC. And if you currently have an active case of COVID-19, wait until after the isolation period is over to make your appointment to prevent spreading the virus at the vaccine site. 

  • Should I get the vaccine if I'm pregnant?

    Both the CDC and the American College of Obstetricians and Gynecologists (ACOG) recommend that pregnant and breastfeeding individuals get vaccinated. Pregnancy is considered a risk factor for severe COVID-19 illness by the CDC.

  • Do the vaccines protect against new strains of COVID-19?

    Research has increasingly found that the available vaccines still protect against variants of the virus like Delta. Moderna, Pfizer, and Johnson & Johnson also all developed booster shots that may help increase immunity against virus variants. Scientists say the virus would have to mutate extensively to escape the vaccine response. They say the vaccines will likely still be protective against new strains that are not significantly different from the original virus.

  • Can I take pain relievers before or after getting vaccinated?

    In order to ensure the vaccine is as effective as possible, some experts are recommending against taking over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) before or after you get injected in an effort to prevent or soothe side effects. NSAIDS include well-known pain relievers such as aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve). A recent study found that NSAIDS dampen the production of protective antibodies against the virus. If you can’t tolerate symptoms post-vaccine, experts recommend using acetaminophen (Tylenol) over an NSAID. If you take NSAIDS long-term for chronic conditions, you should continue following your prescription.

  • How long will it take for the vaccine to work?

    While your body likely will build some immunity to the virus shortly after receiving the single-dose COVID-19 vaccine or the first dose of a two-shot regimen, you won’t be fully protected. To reach full protective immunity, current research suggests you will have to wait two weeks after your second dose for the Pfizer and Moderna vaccines or two weeks after your single dose of the Johnson & Johnson vaccine. 

  • How long will immunity from the vaccine last?

    Some experts believe immunity from the virus will likely last at least a year, and Moderna reports its vaccine will likely provide immunity for at least that period of time. It’s possible you may have to receive the shot annually like a flu shot in order to boost waning immunity. The FDA has recommended Pfizer and Moderna vaccine recipients who are immunocompromised, 65 and older, or at high risk for serious COVID-19 receive a booster six months after their initial vaccine regimen. The FDA recommends all Johnson & Johnson vaccine recipients 18 and older get a booster two months after their shot.

  • What is safe to do after I’ve been fully vaccinated?

    If you’ve been fully vaccinated and are two weeks past the date of your second shot—or your first shot in the case of the Johnson & Johnson vaccine—the CDC says you may begin to loosen safety precautions. According to CDC guidance, you can forego face masks and resume activities that you did prior to the pandemic. The CDC also says domestic travel is considered “low-risk” for fully vaccinated people.

  • Can I still transmit the virus if I’ve been vaccinated?

    The CDC released real-world data showing that the COVID-19 vaccines prevented transmission among healthcare personnel, essential workers, and first responders. But experts say only time will tell if this data will continue to hold up—though it’s likely it will. Early data from Israel shows that the Pfizer vaccine may be effective at preventing transmission of the virus. Johnson & Johnson data also suggests that the vaccine may curb asymptomatic transmission. While the CDC has released guidance stating that people who are fully vaccinated against COVID-19 don’t need to quarantine or test after being exposed to the virus if asymptomatic, experts haven’t taken a hard and fast stance in regards to transmission. 

  • Do I still need to wear a mask after I get vaccinated?

    CDC guidance says you can safely stop wearing your mask indoors and outdoors. But you’ll still need to wear a mask if it’s mandated by your county, state, workplace, or business you’re entering. You can also expect to stay masked up on public transportation like planes, buses, and trains. If you are immunocompromised, the CDC encourages you to wear a mask, even if you’re fully vaccinated.

  • Will the coronavirus vaccine be mandatory?

    Experts believe it’s unlikely the government will institute one overarching COVID-19 vaccine mandate to protect public health. Instead, the government has released recommendations and vaccine mandates for businesses and federal workers. Vaccination requirements are currently being implemented through employers and schools—both of which have instituted vaccine requirements in the past.

How the Vaccine Works in the Body

Explore interactive models that show how the human body responds to a COVID-19 vaccine, and what the body of a vaccinated person would do if exposed to the SARS-CoV-2 virus.

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Page Sources
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  1. United States Food and Drug Administration. COVID-19 Vaccines. Updated February 27, 2021.

Additional Reading