COVID-19 Vaccine Safety & Side Effects

Important Message Regarding Vaccine Symptoms & Side Effects


If you are experiencing any severe symptoms consult your doctor or call 911. If you are still at the vaccine clinic notify the medical personnel in the observation area.

​Vaccine Side Effects

COVID-19 vaccines will have side effects and that’s a good thing!

The technical term for a vaccine that produces side effects is reactogenic: in other words, you react to it when it enters your system. Your reaction may be a sore arm or redness where the injection was given. You may even feel flu-like, have a headache or body aches, or feel very tired. These reactions are completely normal- and do not last very long.

While you may not feel well, the reaction means the vaccine is doing its job. These reactions are a sign of the body’s immune response kicking into gear, creating antibodies that will not only help your body build protection against COVID-19, but train it to fight the virus much faster.

Reactions to the vaccine are just as unique as you are. Not everyone will have the same reaction to the vaccine.  Additionally, your reaction may be different following the second dose compared to the first dose.

Learn more about side effects and find helpful tips to reduce discomfort after your vaccination at: 
What to Expect after Getting a COVID-19 Vaccine

For more information on vaccine safety and side effects for 12-15 year olds visit: 


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What should I do about side effects?


If you are experiencing any severe signs or symptoms, immediately notify the medical personnel in the observation area. If you have already left the clinic, consult your doctor or call 911.

If you have any side effects that bother you or do not go away, call your healthcare provider.  

 Report vaccine side effects to FDA/CDC Vaccine Adverse Event Reporting System (VAERS).

  • Call the toll-free number: 1-800-822-7967
  • Report online on the VAERS website

You will also receive information on how to enroll in v-safe. V-safe is a new, smartphone-based tool that uses text messaging and web surveys to check in with people who have been vaccinated to identify potential side effects after COVID-19 vaccination. V-safe asks questions that help CDC monitor the safety of COVID-19 vaccines. V-safe also provides second-dose reminders if needed and live telephone follow-up by CDC if participants report a significant health impact following COVID-19 vaccination.


Severe Allergic Reactions

There is a remote chance that a COVID-19 vaccine could cause a severe allergic reaction. Severe allergic reactions occur in approximately 2.5 per 1,000,000 individuals (CDC, 2021).  

A severe allergic reaction usually occurs within a few minutes to one hour after getting a dose of a COVID-19 vaccine. However, reactions may occur up to 4 hours after injection. For this reason, the Chester County Health Department requires that you remain at the vaccine clinic for at least 15 minutes for monitoring. Individuals with known allergic reactions (previous anaphylaxis to vaccines, food allergies, insects, etc.) must stay in the observation room for at least 30 minutes. Signs of a severe allergic reaction can include: difficulty breathing, swelling of your face and throat, a fast heartbeat, a bad rash all over your body, dizziness and weakness.
 

If you are experiencing any signs or symptoms, immediately notify the medical personnel in the observation area. If you have already left the clinic, consult your doctor or call 911.



The tables below represent the reported side effects of:

  •  The Moderna Vaccine among participants ages 18 to 64 years old. Individuals ages 65 and older reported less side effects following each vaccine dose.
  • The Pfizer - BioNTech Vaccine among participants ages 18 to 55 years old. Individuals over the age of 55 reported less side effects following each vaccine dose. 
  • The Johnson & Johnson Vaccine among participants 18-59 years within 7 days following vaccination. 

* At the site of injection

  1. Moderna - 1st Dose
  2. Moderna-2nd Dose
  3. Pfizer - 1st Dose
  4. Pfizer- 2nd Dose
  5. Johnson & Johnson
  6. Pfizer - 12 to 15 Year Olds

First Dose

Any Reaction

Mild

Moderate

Severe

Pain*

83.1%

51.1%

31.1%

1%

Redness*

4.5%

3.1%

1.2%

0.3%

Swelling*

5.7%

3.8%

1.7%

0.2%

Fever

3.7%

2.8%

0.7%

0.3%

Fatigue

47.4%

26.1%

19.9%

1.4%

Headache

41.9%

27.4%

13.4%

1%

Muscle Pain

21.3%

11.2%

9.5%

0.6%

Joint Pain

11%

6.4%

4.3%

0.2%

Chills

14%

10%

3.6%

0.4%

Vomiting

1.2%

1%

0.2%

0.2%

Diarrhea

11.1%

9%

2%

0.1%


The side effect tables were condensed for readability.

Significant reaction is typically defined as a reaction that prevents or inhibits daily activity.

References:

CDC: https://www.cdc.gov/mmwr/volumes/70/wr/mm7004e1.htm?s_cid=mm7004e1_w

FDA: https://www.fda.gov/media/144434/download

Moderna: https://www.modernatx.com/covid19vaccine-eua/providers/?gclid=Cj0KCQiA0-6ABhDMARIsAFVdQv9vCknCgqofM6-Z65WuICq6hX7DIq-8vvjKkQMHvQcmLsrF3n4M4eUaAkC8EALw_wcB&gclsrc=aw.ds