J&J Covid Vaccine Recipients Are Better Off Getting Pfizer Or Moderna Booster, NIH Study Suggests

• The NIH study on "mixing and matching" Covid vaccines included more than 450 adults who have received one of the three regimens currently available in the United States: J&J's, Moderna's or Pfizer's.
• Volunteers were divided into groups and received an extra shot of their original vaccine or a booster from a different company.
• Antibody levels were measured two weeks and four weeks after the boosters were given.

Johnson & Johnson Covid-19 vaccine recipients are better off getting a booster shot from Pfizer or Moderna, a highly anticipated U.S. study suggested Wednesday.

The National Institutes of Health study on "mixing and matching" Covid vaccines included more than 450 adults who have received one of the three regimens currently available in the United States: J&J's, Moderna's or Pfizer's. The study, which looks at whether there are any advantages or drawbacks to using different boosters, hasn't yet been peer-reviewed.

Volunteers were divided into groups and received an extra shot of their original vaccine or a booster from a different company. Antibody levels were measured two weeks and four weeks after the boosters were given.

All the combinations boosted antibody levels higher, though Pfizer's and Moderna's boosters appeared to work best. People who received a booster dose of either the Moderna or Pfizer vaccines had a higher increase in their antibody responses more often than those who received an extra dose of J&J, according to the study.

The study showed recipients of Moderna or Pfizer's original vaccines could easily swap third doses; the results were about the same. Volunteers who originally received the J&J vaccine appear to have gotten a better immune response if they got a booster made by Pfizer or Moderna.

There were no serious side effects tied to the additional shots and no new symptoms emerged after participants received the booster shots, researchers said. Two participants vomited after their boosters; one had received Moderna and the other J&J. Two other people who got a J&J booster reported fatigue or insomnia.

"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," researchers wrote in the study. "Heterologous prime boost strategies may offer immunological advantages to optimize the breadth and longevity of protection achieved with currently available vaccines."

J&J's one-dose vaccine uses an adenovirus, while Pfizer's and Moderna's two-dose vaccines use mRNA technology. The thought by scientists is that by "mixing and matching" vaccines that use different platforms, people may be able to get broader protection against the coronavirus and its new variants.

The study is likely to fuel a debate on whether to give additional doses to the millions of Americans who received J&J's vaccines.

Unlike Pfizer's and Moderna's two-shot mRNA vaccines, J&J hoped to offer a one-shot solution that would protect the public enough to help bring an end to the coronavirus pandemic. But its protection, at 72% in the U.S., was viewed by some as inferior to Moderna's and Pfizer's vaccines, which both touted efficacy rates above 90%.

A second dose of J&J's shot results in performance similar to that of the mRNA vaccines, boosting protection from symptomatic infection to 94% when administered two months after the first dose in the United States, according to company data released Sept. 21.

In a separate document published earlier Wednesday, the FDA said data provided by J&J suggests recipients may benefit from an additional dose given two months after the initial shot.

Regulators wrote that estimates on the effectiveness of J&J's single-shot vaccine in trials and real-world studies "are consistently less than the highest effectiveness estimates for the mRNA COVID-19 vaccines."

The findings published Wednesday are expected to be presented at a key Food and Drug Administration vaccine advisory committee meeting Friday.

Last month, U.S. regulators authorized booster shots of the Covid vaccine developed by Pfizer and BioNTech to a wide array of Americans, including the elderly, adults with underlying medical conditions, and those who work or live in high-risk settings, such as health and grocery workers.