Man sitting at the COVID-19 vaccination clinic at CU Boulder.

While side effects can be uncomfortable, they can be one way to show that your immune system is building protection against the COVID-19 virus. 

If you’re feeling hesitant about getting a COVID-19 vaccine because of possible side effects here are some things to know.

1: Side effects are usually mild

Many people don’t experience side effects after being vaccinated, but if you do it’s a normal reaction. The most common side effect is a sore arm, which is similar to many other types of vaccines. For those who do experience side effects, they are usually more common after receiving the second dose of the Moderna or Pfizer vaccines, or after receiving the Janssen (Johnson & Johnson) single-dose vaccine. Keep in mind that side effects may not show up immediately. In many cases, side effects begin a day or two after vaccination.

2: Side effects are temporary

Side effects from the COVID-19 vaccine typically go away within a few days. The current approved vaccines help prevent serious illness, hospitalization and death from COVID-19. While COVID-19 vaccines may cause some temporary discomfort, they are worth the protection they offer against the potentially long-term effects of the COVID-19 virus. Talk with your medical provider about the ways you can help manage these typically mild side effects.

Common COVID-19 vaccine side effects can include:

  • Pain, redness or swelling at the injection site
  • Chills
  • Headache
  • Muscle pain
  • Tiredness (fatigue)
  • Fever
  • Nausea

3: Allergic reactions are extremely rare

Experiencing a severe allergic reaction to the vaccine is extremely rare. Vaccine providers typically require vaccine recipients to wait 15-30 minutes after receiving their vaccine to watch for an allergic reaction. Everyone who receives a vaccine through CU Boulder will complete a form that asks about any previous allergic reactions to other vaccines. If someone were to experience a severe allergic reaction, our health care staff have medications available for immediate treatment. 

4: COVID-19 vaccines cannot infect you with COVID-19

While some of the vaccine side effects can be similar to symptoms of COVID-19, it is important to remember that none of the authorized COVID-19 vaccines in the United States contain live virus. This means that the vaccines cannot infect you with COVID-19, and you will not test positive for a viral test. Keep in mind that vaccines help your body develop antibodies against the virus, so you could test positive on an antibody test, but that does not mean you have the virus.

Questions about the vaccine or potential side effects?

  • Buff Info
    If you have any questions about COVID-19 or the COVID-19 vaccines, you can contact Buff Info. They are available Monday through Friday from 9 a.m. to 6 p.m. The university will extend these hours as needed.

    Call: 303-492-INFO (4636)

  • Medical Services
    Students can schedule a telehealth appointment with a Medical Services provider to discuss vaccine options and side effects. Schedule online through the MyCUHealth portal.
  • Health care providers
    You can also reach out to your personal healthcare provider to discuss possible side effects and which vaccine is right for you. 

Learn more about COVID-19 vaccines