Pfizer vaccine booster
© AP Photo/Matt Rourke
FILE - In this Sept. 14, 2021, file photo, a syringe is prepared with the Pfizer COVID-19 vaccine at a clinic at the Reading Area Community College in Reading, Pa.
The U.S. Centers for Disease Control and Prevention (CDC) said in updated COVID-19 guidelines this week that some immunocompromised people may need a fourth dose of the vaccine.

The agency wrote that people who are over 18 years old who already received an mRNA COVID-19 vaccine primary series and received an additional mRNA vaccine dose may receive a single COVID-19 booster dose - Pfizer/BioNTech, Moderna or Johnson & Johnson - at least six months following their third mRNA vaccine dose.

"In such situations, people who are moderately and severely immunocompromised may receive a total of four COVID-19 vaccine doses," the CDC wrote.

Those who have received two doses of an mRNA vaccine and are moderately or severely immunocompromised, with more than 28 days having passed since the second dose, should receive an additional mRNA dose immediately followed around six months later by a single COVID-19 vaccine booster dose.

People who are over 18, are moderately and severely immunocompromised and have received a single dose Johnson & Johnson COVID-19 vaccine primary series should receive a single Johnson & Johnson, Pfizer/BioNTech or Moderna COVID-19 booster vaccine at least two months after receiving their initial primary dose.

Last week, the agency and U.S. Food and Drug Administration (FDA) gave approval for Americans to mix-and-match COVID-19 booster shots, with Moderna's boosters half the dose that's used for the first two shots.

"Today the currently available data suggest waning immunity in some populations of fully vaccinated people," FDA acting Commissioner Dr. Janet Woodcock said in a statement. "The availability of these authorized boosters is important for continued protection against COVID-19 disease."

Comment: At the beginning the jab roll out people were promised that just one experimental injection was needed to regain their freedoms, but now numerous countries, with Israel at the forefront, are now declaring that only those with multiple boosters will be gifted some, but not all, of their freedoms: Pfizer, Moderna reaping BILLIONS from COVID-19 injection 'booster' market

A third COVID-19 vaccine shot is classified as an "additional dose," and the CDC recommends an additional mRNA vaccine dose for pregnant people who are moderately to severely immunocompromised and for those who are more than 12 years old and have moderate to severe immune compromise.

People with immunocompromising conditions or people who take immunosuppressive medications or therapies are at increased risk for severe COVID-19. According to the CDC, reduced vaccine effectiveness has been observed in immunocompromised participants compared to participants who are not immunocompromised in a limited number of studies.