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COVID-19 Vaccine

By

Margot L. Savoy

, MD, MPH, Lewis Katz School of Medicine at Temple University

Last full review/revision Jun 2021| Content last modified Jun 2021

COVID-19 vaccines provide protection against COVID-19. COVID-19 is the disease caused by infection with the SARS-CoV-2 virus. There are multiple COVID-19 vaccines currently in use worldwide; this topic includes only those vaccines currently in use in the US. In the US, there are no vaccines that have been approved by the U.S. Food and Drug Administration (FDA). However, there are several vaccines that have received Emergency Use Authorization (EUA) from the FDA (BNT162b2 [Pfizer-BioNTech], mRNA-1273 [Moderna], and Janssen Ad26.COV2.S [Johnson & Johnson]).

For more information, see the COVID-19 Advisory Committee on Immunization Practices Vaccine Recommendations and the EUA fact sheets for vaccination providers for the BNT162b2 (Pfizer-BioNTech) , mRNA-1273 (Moderna), and Janssen Ad26.COV2.S (Johnson & Johnson) vaccines. A summary of changes to the 2021 adult immunization schedule is available here.

(See also Overview of Immunization.)

Preparations

There are two preparations of RNA vaccines for COVID-19:

  • BNT162b2 (Pfizer-BioNTech)
  • mRNA-1273 (Moderna)

There is one preparation of an adenovirus 26 vector vaccine for COVID-19:

  • Janssen Ad26.COV2.S (Johnson & Johnson)

Indications

BNT162b2 (Pfizer-BioNTech) has EUA for the prevention of COVID-19 in people 12 years of age and older.

mRNA-1273 (Moderna) has EUA for the prevention of COVID-19 in people 18 years of age and older.

Janssen Ad26.COV2.S (Johnson & Johnson) has EUA for the prevention of COVID-19 in people 18 years of age and older.

Contraindications and Precautions

Contraindications for the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines are

  • Severe allergic reaction after a previous dose of either vaccine
  • Severe allergic reaction to a vaccine component

The main contraindication for the Janssen Ad26.COV2.S (Johnson & Johnson) vaccine is

  • Severe allergic reaction to a vaccine component

Precautions for all three COVID-19 vaccines are

  • Acute anaphylactic reaction immediately after a dose
  • Immunocompromise, including due to immunosuppressant therapy

Appropriate medical treatment to manage immediate allergic reactions must be immediately available in the event an acute anaphylactic reaction occurs after any COVID-19 vaccine is given. COVID-19 vaccine recipients should be monitored for immediate adverse reactions.

Immunocompromised people, including those receiving immunosuppressant therapy, may have a diminished immune response to these vaccines.

A warning has been issued for the Janssen Ad26.COV2.S (Johnson & Johnson) vaccine because cases of thrombosis with thrombocytopenia have been reported after vaccination. Reports suggest an increased risk of thrombosis involving the cerebral venous sinuses and other sites (including but not limited to the large blood vessels of the abdomen and the veins of the lower extremities) combined with thrombocytopenia. Symptom onset is about 1 to 2 weeks after vaccination. Most reported cases have occurred in females ages 18 to 49 years; some have been fatal. The use of heparin may be harmful in people with suspected thrombosis with thrombocytopenia following the Janssen vaccine; alternative treatments may be needed. Consultation with hematology specialists is strongly recommended.

Dose and Administration

The BNT162b2 (Pfizer-BioNTech) vaccine dose is 0.3 mL IM, given in a 2-dose series 3 weeks apart.

The mRNA-1273 (Moderna) vaccine dose is 0.5 mL IM, given in a 2-dose series 4 weeks apart.

The Janssen Ad26.COV2.S (Johnson & Johnson) vaccine dose is 0.5 mL IM.

Adverse Effects

The three COVID-19 vaccines have similar adverse effects.

Rare, severe allergic reactions, including anaphylaxis, have been reported.

Other adverse effects are common:

  • Injection site pain, swelling, and redness
  • Fatigue
  • Headache
  • Muscle and joint pains
  • Fever and chills
  • Nausea
  • Malaise
  • Lymphadenopathy

Because of the risk of reactive lymphadenopathy after COVID-19 vaccination, health care practitioners should discuss mammography with women who are due for a mammogram and who have recently received COVID-19 vaccination. The Centers for Disease Control and Prevention (CDC) states that some experts recommend getting the mammogram before the vaccine or waiting 4 to 6 weeks after getting the vaccine.

More Information

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

  • Advisory Committee on Immunization Practices (ACIP): COVID-19 ACIP Vaccine Recommendations
  • U.S. Food and Drug Administration (FDA): Fact sheet for vaccination providers: Emergency Use Authorization (EUA) of the Pfizer-BioNTech COVID-19 Vaccine (BNT162b2)
  • FDA: Fact sheet for vaccination providers: Emergency Use Authorization (EUA) of the Moderna COVID-19 Vaccine (mRNA-1273)
  • FDA: Fact sheet for vaccination providers: Emergency Use Authorization (EUA) of the Janssen COVID-19 Vaccine (Janssen Ad26.COV2.S)
  • Centers for Disease Control and Prevention (CDC): Guidance regarding COVID-19 vaccination and other medical procedures
  • Summary of changes to the 2021 adult immunization schedule

Drugs Mentioned In This Article

Drug Name Select Trade
heparin PANHEPRIN

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