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CDC Expands Eligibility for COVID-19 Booster Shots  

By: Fatima Amjad, PharmD candidate c/o 2022

             Pharmacists have truly taken on the role of superhero during the coronavirus disease 2019 (COVID-19) pandemic. As of April 6, 2022 more than 239.1 million COVID-19 vaccine doses have been administered by community pharmacies across the United States.1 Community pharmacists have gone above and beyond immunizing eligible patients presenting to their pharmacies, and continue to do so with the expanded availability of booster vaccinations.

Currently, three COVID-19 vaccines are authorized for administration in the United States: Pfizer, Moderna, and Johnson and Johnson (Janssen). Pfizer is authorized for children 5 years and older, while Moderna and Janssen are indicated for those 18 years and older. Both the Moderna and Pfizer vaccines are administered as a two-dose primary series with an additional third dose recommended at least 4 weeks after the 2nd dose for moderate or severely immunocompromised individuals.2 Janssen is administered as a single primary dose, with an additional 2nd dose of an mRNA vaccine (Pfizer or Moderna) given at least 4 weeks after the first dose for moderate or severely immunocompromised individuals.3

All COVID-19 vaccines are administered intramuscularly, with Moderna given as a 0.5 ml dose with a minimum 28 day interval between primary series doses, while Pfizer is administered as a 0.3 ml dose with a minimum 21 day interval between each primary series dose. Conversely, the Janssen COVID-19 vaccine is administered as a single 0.5 ml primary series dose. It is important to note that this Pfizer dose applies to patients 12 years and older. For those less than 12 years old, the authorized dose is 0.2 ml with the same 21 day minimum interval.2

On November 19th of 2021, the Food and Drug Administration (FDA) expanded its initial  emergency use authorization (EUA) for the Pfizer vaccine. This allowed for a single booster dose to be administered at least 6 months after completion of a primary series with any EUA approved COVID-19 vaccine in patients 18 or older.4 There have been numerous changes and updates since November 19th. As of March 13th, 2022 booster shots are available for all 3 EUA COVID-19 vaccines. Pfizer booster vaccinations are recommended for those age 12 and older whereas both Moderna and Janssen booster vaccinations are recommended in those age 18 and older.2 Both Pfizer and Moderna are to be administered at least 5 months after completion of the primary series, whereas patients who were vaccinated primarily with Janssen may receive a booster vaccine at least 2 months thereafter. Patients who are immunocompromised may receive their booster shot at least three months after completion of their primary series with Moderna or Pfizer, and two months after completion with Janssen.2,3

Patients who received a primary dose series are eligible to receive a booster dose with any EUA authorized vaccine. For example, if a patient received two primary series doses with Moderna, and would like to receive their booster shot with Pfizer, they would be able to do so as long as it has been at least 5 months. The same is true with patients who completed their primary series with Pfizer and would like to receive Moderna. It is important to note that patients 12-17 years old are only eligible to complete their booster shot with the Pfizer vaccine, being that Moderna and Janssen are indicated for those 18 years and older.2,3

It should also be mentioned that although patients who completed their primary series with Janssen can also complete their booster shot with the same Janssen vaccine, this is not preferred. The FDA recommends completing booster vaccines with either Pfizer and Moderna. In the event that Moderna or Pfizer is unavailable, or if a patient prefers Janssen despites the potential adverse events (clotting), then Janssen may be administered.2,3 The Pfizer booster vaccines are still being administered as a 0.3 mL dose , whereas the Moderna booster vaccines are being administered as half of the original dose (0.25 mL) seen in the primary two-dose series. The Janssen booster vaccine is still administered as a 0.5 mL dose.2,3

Most recently as of March 29, 2022 the CDC has authorized the administration of a second COVID-19 booster vaccine in individuals at high risk. This includes individuals at least 50 years of age or older or adults aged 12 years and older who are moderately to severely immunocompromised.2 For these patients, the 2nd booster should be administered at least 4 months after the patient has received their first booster dose. 2

Due to the continually evolving nature of the COVID-19 vaccine recommendations, it is essential that healthcare providers stay cognizant of any updates to ensure that patients are receiving the right vaccine for them. With expanded availability of booster vaccines, community pharmacists will continue to play a pivotal role in national immunization efforts.


  1. Covid-19 vaccination Federal Retail Pharmacy Partnership Program. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/covid-19/retail-pharmacy-program/index.html. Accessed April 6, 2022
  2. COVID-19 Booster Shot. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/booster-shot.html#:~:text=Everyone%2012%20years%20and%20older,-When%20to%20get>. Accessed April 6, 2022.
  3. Interim clinical considerations for use of covid-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#vaccination-people-immunocompromised. Published March 2, 2022. Accessed April 6, 2022.
  4. Coronavirus (COVID-19) Update: FDA Expands Eligibility for Pfizer-Biontech COVID-19 Booster Dose to 16- and 17-Year-Olds. U.S. Food and Drug Administration, FDA, https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-expands-eligibility-pfizer-biontech-covid-19-booster-dose-16-and-17. Accessed April 6, 2022.
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