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, four vaccines have received emergency use authorization (EUA) from the Food and Drug Administration (FDA). Of those four, 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?

    The Food and Drug Administration (FDA) has fully approved or granted emergency use authorization (EUA) to four COVID-19 vaccines in the United States:

    In May of 2022, the FDA scaled back its EUA for the J&J vaccine because of concerns about blood clot side effects. The CDC recommends that people receive one of the mRNA vaccines (Moderna or Pfizer) or the Novavax vaccine over the J&J 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 ages 6 months and older across the U.S. is now eligible to be vaccinated. Appointments, including walk-in appointments, are now readily available nationwide. You can also search for pharmacies and providers that offer vaccination on

  • 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

  • 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. According to the CDC, if you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, you can get a COVID-19 vaccine anytime; you do not have to wait. 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 and Omicron. The FDA recently granted EUAs for updated bivalent COVID-19 boosters of the Moderna and Pfizer COVID-19 vaccines. The updated (bivalent) boosters are called “bivalent” because they protect against both the original virus that causes COVID-19 and the Omicron variant BA.4 and BA.5. People ages 5 years and older are eligible to get an updated booster at least 2 months after completing the primary series or last booster.

  • 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, Moderna, and Novavax vaccines or two weeks after your single dose of the J&J vaccine. According to the CDC, you are considered up to date immediately after you have received the most recent booster recommended for you.

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

    According to CDC guidance, COVID-19 prevention measures such as mask-wearing should be based on COVID-19 levels in a community and an individual's risk for serious illness. For example, a mask is not necessary for most people when the community level is low or medium. If the community level is high, wearing a mask is recommended. The CDC says that people may choose to wear masks at any time. For example, public transportation does not require masks, but the CDC recommends wearing one on indoor public transportation. If you are immunocompromised, the CDC encourages you to wear a mask, even if you're fully vaccinated.

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.

More In Coronavirus (COVID-19)

Page Sources
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  1. Centers for Disease Control and Prevention. Stay Up to Date with Vaccines.

  2. Centers for Disease Control and Prevention. Use of COVID-19 Vaccines in the U.S: Appendices.

Additional Reading