COVID-19 Vaccine

There are 2 mRNA vaccines for COVID-19 used in the United States. mRNA vaccines contain messenger RNA of the virus that has been manufactured in a laboratory. The mRNA gives cells in the body instructions for how to make a protein or a piece of a protein of the virus. The body's immune system is then able to recognize and protect against future infection.

There is 1 recombinant spike protein vaccine for COVID-19 used in the United States. This vaccine contains a harmless version of the coronavirus spike protein that is manufactured in a laboratory and is recombined with other substances. The body's immune system is then able to recognize and fight the spike protein if a person becomes infected.

COVID-19 vaccines do not contain any live virus, so they cannot give people the COVID-19 infection. These vaccines do help people develop immunity to protect against severe outcomes resulting from COVID-19 infection.

All COVID-19 vaccines are injected into a muscle.

Recommendations for COVID-19 vaccines vary. The number of doses a person receives depends on their age, on whether they have a weakened immune system, and on whether they ever received any doses of vaccine.

All vaccine-related information, including who should and who should not receive the vaccine, for all age groups and people with special conditions, is available from the CDC at Interim Clinical Considerations for Use of COVID-19 Vaccines in the United States.

The COVID-19 vaccines cause similar side effects, which include:

• Pain, swelling, and redness at the injection site

• Tiredness

• Headache

• Muscle and joint pains

• Fever and chills

• Nausea and vomiting

• Swollen lymph nodes

Side effects tend to last several days.

There is a very small chance of a severe allergic reaction. This usually occurs within a few minutes to 1 hour after getting a dose of the vaccine and may require emergency treatment. If a person develops difficulty breathing, they or someone with them should call for emergency medical care (911 in the United States) or go to the nearest hospital. People who have had severe allergic reactions to other vaccines or injectable medications should discuss the risk of an allergic reaction with their doctor and be observed after receiving the vaccine.

See also CDC: Coronavirus Disease 2019 (COVID-19) Vaccine Safety.

The heart problems myocarditis and pericarditis have been reported after people have received any of the vaccines, which suggests there may be an increased risk of these problems after vaccination. The risk is highest in young males. Vaccine recipients should seek medical attention right away if they have chest pain, shortness of breath, or feelings of having a fast-beating, fluttering, or pounding heart after vaccination.

For more information about side effects, see the package inserts.

The following English-language resources may be useful. Please note that The Manual is not responsible for the content of these resources.

1. Centers for Disease Control and Prevention (CDC): COVID-19 Vaccines

2. CDC: Interim Clinical Considerations for Use of COVID-19 Vaccines in the United States

3. CDC: Coronavirus Disease 2019 (COVID-19) Vaccine Safety

4. European Centre for Disease Prevention and Control (ECDC): Coronavirus Disease (COVID-19): Recommended vaccinations