People who get the COVID-19 vaccine may notice some soreness in their arm and other side effects, which is normal. The good news is that the symptoms are usually short lived, according to experts in the Johns Hopkins School of Medicine. There are other things to know after a shot, too, such as when to follow up and what other precautions to take. Here are some answers from Dr. Panagis Galiatsatos, an assistant professor in the Division of Pulmonary and Critical Care Medicine, and Namandjé Bumpus, professor and director of the Department of Pharmacology and Molecular Sciences.
What can you expect right after and a day after getting a COVID-19 vaccines?
Galiatsatos: A good portion of individuals will develop some symptoms after receiving the vaccine, especially the second dose. These can range from fatigue to chills to a low grade fever. I would encourage trying to give yourself 8 to 12 hours after receiving the vaccine to rest at home, as these mentioned symptoms impact people differently. You should also expect some level of arm soreness from where the vaccine was inserted.
How do I treat side effects and when do I need to call a doctor?
Galiatsatos: The majority of side effects, as described, will be transient. After a few hours they will self-resolve. Staying well hydrated will be key to help mitigate some of the side-effects. However, if you develop chills or a fever, make sure you have discussed with your clinician what is the most appropriate course of action. For some, acetaminophen (e.g. Tylenol) would be fine to take to for fevers and/or chills. If other side effects occur, such as shortness of breath or rash, I would notify your clinician as soon as possible.
When do I need my second shot, and do I have some leeway on timing?
Bumpus: The established efficacy of the vaccines is based on receiving the second shot at the recommended interval. For the Pfizer-BioNTech vaccine this is three weeks (21 days) after the first shot and for the Moderna vaccine this is four weeks (28 days) after the first shot. It is important to receive the second shot as close as possible to the recommended interval. The second dose should not be scheduled for an earlier date, however, based on current guidance, the second shot will still be considered valid if administered within a grace period of four days earlier than the recommended interval. Data from clinical trials indicate that when it is not feasible to adhere to the recommended interval between doses, the second shot can be administered up to six weeks (42 days) after the first shot and current guidance from the [Centers for Disease Control] allows for this. However, again, it is important to have the second shot administered as close to the recommended interval as possible.
How long does it take for the vaccine to build immunity?
Bumpus: The Pfizer-BioNTech vaccine exhibited efficacy of 95% at preventing COVID-19 at least seven days after the second shot. The Moderna vaccine was 94% efficacious in preventing COVID-19 at least 14 days after the second dose.
Do I still have to wear a mask and take other measures to keep myself and other safe?
Galiatsatos: Yes. The vaccines are designed to protect you from getting sick with COVID-19. If you do you become infected with SARS-CoV-2, you are unlikely to develop severe, life threatening COVID-19. However, it is unclear if the vaccine will stop the spread of the virus. Therefore, until enough people are vaccinated, we encourage the hygienic interventions to continue. The vaccine protects you, but will not protect a person who has not been vaccinated from developing severe COVID-19.
If I had COVID-19 do I still need a vaccine?
Bumpus: Yes, a COVID-19 vaccine would likely be beneficial. Because of the severe health risks of COVID-19, vaccination is important regardless of whether a person has already had COVID-19. While vaccine supplies remain limited, people with recent acute SARS-CoV-2 infection may want to discuss the timing of their need for vaccination with their healthcare provider.