FDA Authorizes 3rd COVID-19 Booster Shot—Here Are the Side Effects to Expect

The Federal Drugs Administration on Thursday amended its emergency use authorizations for the Moderna and Pfizer-BioNTech COVID-19 vaccines to allow a third booster shot for certain immunocompromised people to help prevent infection.

Many people who have received either brand’s mRNA-based vaccine experienced uncomfortable side effects after the second dose. Symptoms included muscle pain, fatigue and even fever.

Those eligible for the additional booster shot can expect similar side effects after the third dose, according to a study from Israel, where people aged 60 and older have been offered a third dose of the vaccine since late July.

Among more than 4,500 people who received a third dose of the Pfizer vaccine between July 30 and August 1, about 88 percent reported feeling “similar or better” than how they felt after the second shot, according to the study, conducted by Israel’s largest health provider, Clalit.

About 31 percent reported side effects such as pain or swelling in the area of the injection site. About 20 people, or 0.4 percent, said they suffered from difficulty breathing. And 1 percent said they sought out medical care due to one or more side effects, according to the findings, which were released on Sunday.

“Although we do not yet have long-term research on the efficacy and safety of the third booster dose, for the personal risk management of any person aged 60 plus, these findings continue to point to the benefit of immunization now, along with careful behavior among adults and avoiding gathering in closed spaces,” Ran Balicer, Clalit’s chief innovation officer, told Reuters.

The FDA’s amended authorizations apply to “solid organ transplant recipients or those who are diagnosed with conditions that are considered to have an equivalent level of immunocompromise.”

“People who are immunocompromised in a manner similar to those who have undergone solid organ transplantation have a reduced ability to fight infections and other diseases, and they are especially vulnerable to infections, including COVID-19,” the agency said in a press release Thursday. “The FDA evaluated information on the use of a third dose of the Pfizer-BioNTech or Moderna Vaccines in these individuals and determined that the administration of third vaccine doses may increase protection in this population.”

The CDC is set to meet on Friday to discuss further clinical recommendations regarding immunocompromised individuals.

The Pfizer-BioNTech COVID-19 vaccine is currently authorized for emergency use in individuals ages 12 and older. The Moderna vaccine is authorized for emergency use in individuals ages 18 and older.