A study from the National Institutes of Health (NIH) found that mixing and matching COVID-19 vaccines for booster shots could be safe and effective, though the Centers for Disease Control and Prevention (CDC) still recommends not mixing vaccines.
The “Mix and Match Study” was published Wednesday on medRxiv.org and has not yet been peer-reviewed.
The study analyzed more than 450 people who received a COVID-19 vaccine regimen from Pfizer, Moderna, or Johnson & Johnson.
Those participants were divided into groups and received either an extra shot of their original vaccine or a booster from a different company. Their antibody levels were measured two weeks and four weeks after the shots were administered.
The researchers found that people who received a J&J vaccine produced stronger antibody levels after receiving a booster shot from either Pfizer or Moderna, compared to another J&J shot.
As for those who were originally vaccinated with Pfizer or Moderna shots and received a booster shot from either company, the study found they produced similarly strong immune responses.
“These data suggest that if a vaccine is approved or authorized as a booster, an immune response will be generated regardless of the primary COVID-19 vaccination regimen,” wrote the researchers.
The authors of the study say the participants reacted to the new round of shots similarly to how they reacted to the primary series.
“Injection site pain, malaise, headache, and myalgia occurred in more than half the participants,” they wrote.
The researchers concluded that the homologous and heterologous booster vaccinations were well-tolerated and created an immune response in adults who completed a primary COVID-19 vaccine regimen at least 12 weeks earlier.
NBC News reports that the findings of this study will be presented to the Food and Drug Administration (FDA) advisory committee on Friday, when they’ll be meeting to consider recommending the authorization of booster shots for the Moderna and J&J vaccines.
The only booster shot approved so far in the U.S. is Pfizer’s and it's only available for certain groups. At this time, the CDC says the authorization only applies to people whose primary series was with Pfizer’s vaccine.
“People in the recommended groups who got the Moderna or J&J/Janssen vaccine may need a booster shot,” wrote the CDC. “More data on the effectiveness and safety of Moderna and J&J/Janssen booster shots are expected soon. With those data in hand, CDC will keep the public informed with a timely plan for Moderna and J&J/Janssen booster shots.”