Starting in September, U.S. adults 18 and older who have received both Moderna or Pfizer COVID-19 vaccines will be eligible for a booster dose.
The booster should be given at least eight months after a person’s last COVID vaccine.
Dr Hana Mohammed El Sahly is professor of molecular virology and microbiology and is part of vaccine and treatment evaluation at Baylor College of Medicine in Houston. She told Texas Standard that Moderna and Pfizer’s two-dose vaccination schedules provide effective protection against severe cases of COVID-19 and are effective against the delta variant, which currently accounts for most cases. But the first two shots were less effective in preventing mild cases of the virus.
“Hospitalization and death are prevented, 90% or more, by the first two doses,” El Sahly said. “And it remains the case.”
El Sahly says two more levels of review need to be done before booster shots are available. The FDA must approve the recall, and the American Committee on Immunization Practices, or ACIP, which is an advisory committee to the CDC, must assess the effectiveness of the vaccine to determine which populations are good candidates for the recalls.
Pfizer has submitted for approval a booster dose identical to its first two injections. El Sahly says Moderna is set to submit its booster to the FDA soon.
Currently, adults with weakened immune systems are eligible to receive a third dose of a COVID-19 vaccine. A booster could be important for people in these situations, as studies show that they do not get the same level of protection from the first two doses as those without compromised immune systems.
“These are people who have had a solid organ transplant, they have cancer and are taking immunosuppressive drugs, they potentially have autoimmune diseases and they regularly take drugs that lower their immunity,” said El Sahly.