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March 03, 2021

What to Expect After COVID-19 Vaccine

What to Expect After COVID-19 Vaccine

As the COVID-19 vaccine rollout has expanded to more Hoosiers in recent days, you may be one of the many thousand who have recently received a COVID-19 vaccine.

You’ve made an important decision that will protect you and those around you. But after the simple jab to get the vaccine, you might have gone back home and thought “Well, now what?” We have provided answers to your common questions:

What are the side effects from COVID-19?

The vaccines can cause mild to moderate symptoms. On your arm, this may include pain and swelling. On the rest of your body, you may experience fever, chills, tiredness or headaches. The side effects of the Pfizer and Moderna vaccines are similar to what we see with other common vaccines.

These vaccines do not have the live virus and cannot give you COVID-19. Side effects to the vaccine are a good sign – this is your body gearing up to fight the virus. It means the vaccine is working.

How long will side effects from vaccine last?

COVID-19 vaccine side effects last typically 24 to 48 hours after vaccination.

If I get the Moderna or Pfizer vaccine, why do I need a second dose?

Many vaccines require an initial dose and a follow-up “booster” shot to strengthen the immune response. The Moderna and Pfizer vaccines both need two doses to provide the greatest protection. For example, in the Pfizer clinical studies, the first shot only was about 52% effective after one dose. Effectiveness jumped to 95% after the second shot.

Can I still get COVID-19 after getting the vaccine?

Yes. It takes time for your body to build robust protection against the disease. Vaccine protection typically takes a few weeks. Pfizer and Moderna calculated their effectiveness rates 1-2 weeks after the second dose. Johnson & Johnson’s was measured 28 days after the single dose.

As your body builds protection or even in the days leading up to when you first got vaccinated, you may have been exposed to the virus.

The good news: experts believe based on early data that a great benefit from getting a COVID-19 vaccine is that it helps prevent you from developing severe case of disease even if you do get COVID-19.

Can I spread the virus to others if I’ve gotten the vaccine?

The answer is just not clear yet. While the vaccine clinical trials were set up to determine whether the vaccines were effective against preventing symptoms, they did not provide the answers on virus transmission.

What’s still unclear is: Could someone who has the vaccine develop an infection without symptoms (your body might still fight those off), but as they talk or sneeze are they then passing that along to others? And would it be enough to make others sick?

Can I get together with friends and family again after getting the COVID-19 vaccine?

Everyone wants to know the answer to that question! And certainly a vaccine will make things safer. But a couple warnings. Remember, vaccines don’t work right away – full protection doesn’t take affect until after the second dose.

As vaccine rollout expands, many in your close circles will not have had a vaccine – children won’t be approved for a vaccine for a while. Follow the CDC and the Indiana Department of Health for the latest information.

Do I still need to wear a mask and social distance?

Remember, it will take a while for your body to build full immunity from the vaccine. And scientists and researchers continue to work on understanding how vaccines work against passing the virus to others – many who aren't vaccinated yet.

It’s important to continue wearing your mask, social distancing and practicing good hand hygiene. A vaccine is just one tool to help stop the COVID-19 pandemic. We’ll need to use all the tools available.

Learn more about the COVID-19 vaccine or find full COVID-19 resources on our COVID-19 Resource Center. You can also learn more by visiting the vaccine resources at or visiting

Photo: The first day of COVID-19 vaccine shots at Riley Hospital for Children. Photographed on Dec. 18, 2020. (Mike Dickbernd)

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COVID-19 is a disease caused by a coronavirus named SARS-CoV-2. Find answers to symptoms, diagnosis, vaccine and testing questions.