Left up to the imagination, vaccine reactions sound scary, but COVID-19 vaccine reactions are similar to those that may occur after the flu shot or the shingles vaccine. Dr. Sharon Wright, Infection Control Lead at Beth Israel Lahey Health explains that “fever, chills, headache, joint and muscle aches” or “pain at the injection site” can occur and may last for 1-2 days. Around 10 to 30 percent of people who get the vaccine will experience one or more of these symptoms after the first and second injection.

Importantly, these reactions are not because there is any live virus within your body; they come from your immune system activating. “They’re really a good sign that the vaccine is doing its job to build protections for you in the future,” said Dr. Wright.

In the UK rollout of the Pfizer/BioNTech vaccine, two participants had allergic reactions. The Centers for Disease Control and Prevention (CDC) has since stated that anyone with a history of severe reactions to any of the components of the COVID-19 vaccine should not get vaccinated.  People with severe reactions after other types of vaccinations or injectable medications should consult with their doctor before having the vaccination and be monitored for 30 minutes afterward. All UK participants with allergic reactions have since recovered.

Dr. Sarah Mbaeyi, a medical officer at the CDC’s National Center for Immunization and Respiratory Diseases, said that people who report “anaphylactic reactions to other vaccines or injectables” can still get the vaccine but that they should “be counseled” on the risks and “balance these risks against the benefit of vaccination.”

Mbaeyi notes that those who have other allergies like latex, food, pollen, or other substances, without anaphylactic reactions are recommended to get the Pfizer/BioNTech vaccine and require no additional precautions.

What reactions can I expect after the COVID-19 vaccine?

Sharon Wright, MD, MPH, Infection Control Lead, BILH Incident Command, talks about the possible side effects of the COVID-19 vaccine and why your body may have certain reactions.