Pfizer begins testing COVID-19 booster shot with pneumococcal vaccine in older adults

CDC: Younger adults 18-49 account for one-third of COVID-19 hospitalizations in US

U.S. health officials warn COVID-19 still poses a threat to young adults.

NEW YORK - Pfizer has started testing a booster shot of its COVID-19 vaccine in combination with a pneumococcal vaccine candidate, the company announced this week.

The company has enrolled 600 fully vaccinated adults age 65 or older for the trial, which aims to analyze the safety of when both vaccines are co-administered and the immune responses produced by each shot.

The participants will have received their second dose of the Pfizer-BioNTech vaccine at least six months prior to entering the combination study.

Individuals in the study will receive either the company’s 20-valent pneumococcal conjugate vaccine candidate (20vPnC) plus a third dose of the Pfizer-BioNTech COVID-19 vaccine — referred to as a "booster" — or they’ll get the 20vPnC shot plus a dummy booster.

Some will also get the Pfizer booster shot plus a 20vPnC placebo, the company said.

University Of Miami Health Distributes Vaccinations To Underserved Communities

FILE - A person receives a Pfizer-BioNTech COVID-19 vaccine from a licensed practical nurse at the UHealth's pediatric mobile clinic on May 17, 2021 in Miami, Florida. (Photo by Joe Raedle/Getty Images)

Pneumococcal disease is an infection caused by a type of bacteria called Streptococcus pneumoniae, according to the U.S. Centers for Disease Control and Prevention. It can cause pneumonia, bloodstream infections or meningitis and causes an estimated 150,000 hospitalizations in the U.S. each year.

Pfizer’s pneumococcal candidate is being developed to protect adults against "invasive disease and pneumonia caused by 20 serotypes of Streptococcus pneumoniae," the company said.

"Together, the 20 serotypes included in 20vPnC are responsible for a majority of currently circulating pneumococcal disease globally," Pfizer said in a statement.

The question of whether booster shots will be needed for COVID-19 vaccines currently being administered in the U.S. remains unclear.

There are currently three vaccines authorized for emergency use by the Food and Drug Administration — the two-dose Pfizer shot for ages 12 and older, Moderna’s two-dose vaccine for adults, as well as a single-dose shot developed by Johnson & Johnson for individuals 18 and up.

"The need for and timing for COVID-19 booster doses have not been established. No additional doses are recommended at this time," the CDC currently states on its website.

Regardless, health officials and vaccine developers have been preparing for the possibility in case they’re needed against troubling new variants, or versions of the coronavirus, that are circulating. Studies have shown that the mRNA vaccines made by Pfizer and Moderna maintain high efficacy at least six months after being vaccinated — and possibly longer.

To date, nearly 50% of American adults have been fully vaccinated against the virus and at least 61.5% have received at least one dose of a vaccine, CDC data shows.

This story was reported from Cincinnati.