Vaccine Safety

The Food and Drug Administration is responsible for making sure that any authorized vaccines are safe and that they work. This process can take many months, but because of an unprecedented scientific effort, financial support and willing volunteers, researchers were able to test the vaccine on large groups of people much faster than ever before.

Potential Side Effects

When you receive the vaccine, your immune system starts to ward off COVID-19. This can cause some side effects. The majority of patients have had mild side effects. A few patients have experienced moderate reactions.

You may see reactions in the immediate area of where you receive your shot. This includes redness, swelling and pain. Other side effects include fever, fatigue, headache, chills, vomiting, diarrhea and muscle or joint pain. In general, these side effects are like having a flu-like illness. There may be other reactions that are not currently known.

While the side effects can be uncomfortable, it is necessary for you to get both doses of the vaccine. Skipping the second dose will greatly reduce your protection from COVID-19.

You’ll receive information about potential side effects at the time of your vaccination.

Reporting reactions or side effects

The Vaccine Adverse Event Reporting System collects information on reported side effects. Healthcare providers use the system to report vaccination side effects.

Patients and caregivers should report adverse events as well. Even if you are unsure that the vaccine caused the adverse event, we encourage you to report them in any case.

  • If you experience a severe allergic reaction, call 9-1-1, or go to the nearest hospital.
  • Call your healthcare provider if you have any side effects that bother you or do not go away.
  • Report vaccine side effects to the Vaccine Adverse Event Reporting System (VAERS). You can also call them toll-free at 1-800-822-7967. Please specify which vaccine you received in the first line of box #18 of the report form:
    • Moderna COVID-19 Vaccine EUA or
    • Pfizer COVID-19 Vaccine (Comirnaty)
    • Johnson & Johnson COVID-19 Vaccine EUA


V-safe is a CDC smartphone app that monitors the safety of COVID-19 vaccines. You’ll receive text messages and daily symptom surveys to see how you’re feeling after your vaccination. V-safe will remind you to get your second dose if needed. The CDC will follow-up by telephone if you report a significant adverse event. Learn more and register for the app on the CDC website.

Reporting to Manufacturers

  • Moderna vaccine: Report side effects at 1-866-MODERNA (1-866-663-3762).
  • Pfizer vaccine: Report Pfizer side effects online or at 1-800-438-1985.
  • Johnson & Johnson: Report side effects at 1-800-565-4008.
Getting a COVID-19 Vaccine

important things to know

Getting a COVID-19 Vaccine

Information on potential side effects, how to report side effects to and other things to keep in mind.

Dr. Michael Lauzardo Answers Questions About Vaccine Safety and Effectiveness

Dr. Lauzardo Discusses Side Effects

Listen to UF Health expert Dr. Michael Lauzardo discuss current side effects from the vaccine trials.

Common Questions about vaccine safety

If I get a vaccine, do I still need to wear a mask and practice physical distancing?

Given national guidance from the Centers for Disease Control and Prevention (CDC) and in concert with the State University System, the University of Florida has made masks optional rather than required for students, faculty, staff and guests on UF property and in UF facilities. Those not fully vaccinated for COVID-19 are recommended to continue wearing masks, according to CDC guidance. It is recommended (but not required) that those who have not been vaccinated continue to practice physical distancing. We encourage everyone to be mindful that this is a time of adjustment and to be considerate and respectful of others’ personal space.

How do you counsel people to feel safe about the vaccine?

Can children get the COVID-19 vaccine?

The FDA has authorized the use of the Pfizer (Comirnaty) vaccine for 5 to 17 year olds.

Who should I contact if I have questions about whether to receive the vaccine?

You should contact your primary care physician to discuss your concerns. Additionally, the State of Florida has set up a 24-hour hotline that is dedicated to answer your questions or concerns about the vaccine. The number is 866-779-6121. The call center is open 24 hours a day, 7 days a week.

What is Emergency Use Authorization?

The FDA can issue an Emergency Use Authorization (EUA). These are issued for public health emergencies. For the FDA to issue an EUA for COVID-19 vaccines, safety and effectiveness of the product must be demonstrated through a phase 3 clinical trial, and certain criteria must be met, including that there are no approved and available alternatives. The FDA has approved an EUA for the Johnson & Johnson COVID-19 vaccine.

  • The FDA fully approved the Pfizer BioNTech vaccine on August 23, 2021. This vaccine was renamed Comirnaty.
  • The FDA approved the Moderna COVID-19 vaccine for individuals over the age of 18 on January 31, 2022. This vaccine was renamed Spikevax.

FDA full approval was based on continuing clinical evidence of the vaccine’s safety and efficacy. Moderna has been shown to be at least 93% effective, and Pfizer has been shown to be at least 88% effective.

CDC Information

Vaccine Testing and the Approval Process

The Centers for Disease Control and Prevention offer resources describing how vaccine development and testing occur.

COVID 19 Testing in the Emerging Pathogens Institute

COVID-19 Vaccines for Pregnant or Nursing Women

The effectiveness of preventing COVID-19 is expected to be the same in pregnant women as other people. If you are pregnant, your exposure to COVID-19 and the number of cases in your community are important to consider when getting vaccinated. Pregnant women are vulnerable to more severe illness from COVID-19 compared to nonpregnant women of reproductive age. Scientific studies to date have shown no safety concerns for babies born to people who were vaccinated against COVID-19 during pregnancy.

Are the vaccines safe for women who are nursing?

The Pfizer and Moderna vaccines are considered low-risk for breastfeeding individuals or their children. Women who are nursing will be offered COVID-19 vaccination based on the same priority groups as others. 

Are the vaccines safe for women who want to become pregnant?

COVID-19 vaccination is recommended for women considering or trying to become pregnant. Pregnancy testing is not recommended prior to vaccination. If you become pregnant after the first dose, the second dose should still be taken. If you are trying to get pregnant, consider signing up for the CDC V-SAFE registry so you can report if you become pregnant within 30 days of vaccination.

COVID-19 Vaccines & Allergies

It is important to let the vaccination team know about your allergies because you will be monitored for 30 minutes for a potential reaction. All vaccination teams have trained personnel and are equipped with medications and protocols to handle a severe reaction. Consult with your doctor about receiving the vaccine if you have additional questions.

If I have an egg or gelatin allergy, can I get an mRNA COVID-19 vaccination (Pfizer or Moderna)?

Neither vaccine contains eggs or gelatin; thus, persons with allergies to these substances should be able to get vaccinated. Consult with your doctor about receiving the vaccine if you have additional questions.