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Instructions for After Receiving the COVID-19 Vaccine

Updated: February 11, 2021

Instructions to follow after the vaccine

The following are instructions to follow after your child receives the COVID-19 vaccination.

  1. CDC recommendations state that all vaccine recipients be observed for 15-30 minutes after vaccination. Licensed Children's Mercy staff can be found in the observation area and are available to answer any questions.
  2. Please take time as you wait after your vaccine to register with V-Safe, the CDC’s smartphone tool that surveys vaccine recipients for side effects. You must use Google Chrome to access the link. Your participation in the CDC’s V-Safe makes a difference- it helps keep COVID-19 vaccines safe.
  3. Please make sure that you keep your CDC COVID-19 Vaccination Record Card and bring it back with you for your 2nd vaccination. While we have an electronic record, this is your personal proof of vaccination, noting the date, brand, and lot number of your vaccine.
  4. Even after vaccination, we are still required to mask and avoid large crowds or gatherings to prevent spread of COVID-19.
  5. Please make sure you have the date and time for your 2nd dose before leaving after your 1st vaccine. It is extremely important to keep this appointment.  You will need the 2nd dose to have the full effect of the vaccine.  There is a specific timeframe to receive the 2nd dose.  Please make this appointment a priority.
  6. If you have any reactions or concerns after your vaccination, please call our Nurse Advice Line at (816) 234-3188 for assistance with next steps.  

What to expect after getting the vaccine


COVID-19 vaccination will help protect you from getting COVID-19.

You may have some side effects, which are normal signs that your body is building protection. These side effects may affect your ability to do daily activities, but they should go away in a few days.

Common side effects

On the arm where you got the shot: 

  • Pain
  • Swelling

Throughout the rest of your body:

  • Fever
  • Chills
  • Tiredness
  • Headache

Helpful tips

If you have pain or discomfort, talk to your doctor about taking an over-the-counter medicine, such as ibuprofen or acetaminophen.

To reduce pain and discomfort where you got the shot:

  • Apply a clean, cool, wet washcloth over the area.
  • Use or exercise your arm.

To reduce discomfort from fever:

  • Drink plenty of fluids.
  • Dress lightly.

When to call the doctor

In most cases, discomfort from fever or pain is normal. Contact your doctor or health care provider:

  • If the redness or tenderness where you got the shot increases after 24 hours.
  • If your side effects are worrying you or do not seem to be going away after a few days.

If you get a COVID-19 vaccine and you think you might be having a severe allergic reaction after leaving the vaccination site, seek immediate medical care by calling 911.

About your second shot

Both COVID-19 mRNA vaccines will need 2 shots to get the most protection. The timing between your first and second shot depends on which vaccine you received. You should get your second shot:

  • For the Pfizer-BioNTech, 3 weeks (or 21 days) after your first shot.
  • For the Moderna, 1 month (or 28 days) after your first shot.

You should get your second shot as close to the recommended 3-week or 1-month interval as possible. However, there is no maximum interval between the first and second doses for either vaccine. You should not get the second dose earlier than the recommended interval. ​


  • Side effects may feel like flu and even affect your ability to do daily activities, but they should go away in a few days.
  • With most COVID-19 vaccines, you will need 2 shots in order for them to work. Get the second shot even if you have side effects after the first shot unless a vaccination provider or your doctor tells you not to get a second shot.
  • It takes time for your body to build protection after any vaccination. COVID-19 vaccines that require 2 shots may not protect you until a week or two after your second shot.

It is important for everyone to continue using all the tools available to help stop this pandemic as we learn more about how COVID-19 vaccines work in real-world conditions. Cover your mouth and nose with a mask when around others, stay at least 6 feet away from others, avoid crowds, and wash your hands often. ​

Sign up for v-safe

The CDC offers v-safe, a smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after you receive a COVID-19 vaccination. Children's Mercy encourages all patients who receive the vaccination to participate in v-safe.

Your participation in CDC's v-safe makes a difference — it helps keep COVID-19 vaccines safe.