US Begins Study on Mixing COVID-19 Vaccines, Booster Shots

US Begins Study on Mixing COVID-19 Vaccines, Booster Shots
Vials with Pfizer-BioNTech and Moderna COVID-19 vaccine labels in an illustration picture on March 19, 2021. (Dado Ruvic/File Photo/Reuters)
Isabel van Brugen

The National Institutes of Health (NIH) announced June 1 that it has started a clinical trial of adults fully vaccinated against COVID-19 receiving a different booster shot approximately three to four months later.

The study will determine the safety and immunogenicity of mixed booster regimens against the CCP virus and emerging variants.
Some 150 adults who have received one of the three COVID-19 vaccines currently available under the Food and Drug Administration’s (FDA) emergency use authorization in the United States will take part in the trial, the NIH stated.

The three COVID-19 vaccines currently available in the United States are those made by Johnson & Johnson, Moderna, and Pfizer-BioNTech.

“Although the vaccines currently authorized by the U.S. Food and Drug Administration offer strong protection against COVID-19, we need to prepare for the possibility of needing booster shots to counter waning immunity and to keep pace with an evolving virus,” U.S. National Institute of Allergy and Infectious Diseases (NIAID) Director Dr. Anthony Fauci said in a statement.

“The results of this trial are intended to inform public health policy decisions on the potential use of mixed vaccine schedules should booster doses be indicated.”

Each vaccine group will consist of about 25 people aged 18 to 55, and another 25 people aged 56 and above.

“Twelve to 20 weeks following their initial vaccination regimen, participants will receive a single booster dose of the Moderna COVID-19 vaccine as part of the trial,” the NIH stated.

Those who have yet to receive a vaccine authorized by the FDA for emergency use will also be able to enroll in the trial in a separate group, and will be administered two Moderna shots. Those participants will receive a booster shot of one of the three vaccines about three to four months later.

The NIH said initial trial results are expected in late summer this year.

Fauci last week said that Americans vaccinated against COVID-19 will most likely need a booster shot at some point in the future to guarantee continued protection, but that the timing remains unclear.

“I don’t anticipate that the durability of the vaccine protection is going to be infinite—it’s just not. So I imagine we will need, at some time, a booster. What we’re figuring out right now is what that interval is going to be,” Fauci said during a Senate Appropriations Subcommittee hearing while testifying about the state of medical research and the NIH budget for fiscal year 2022.

Fauci said that a possible timeline for a booster is being studied by public health experts.

“We know from studies following people from the original clinical trials that the protection goes out at least six months and likely a year,” he said. “I believe we will need a booster. I’m not exactly sure when.”

Isabel van Brugen is an award-winning journalist. She holds a master's in newspaper journalism from City, University of London.
Related Topics