Recipients of Johnson & Johnson's
The NIH's mix-and-match COVID vaccine study--which tested antibody levels following booster doses from either the Pfizer-BioNTech, Moderna, or Johnson & Johnson vaccines--included more than 450 adult participants who have received of the three vaccine regimens authorized for use in the U.S.
J&J's vaccine uses a different platform than the Pfizer-BioNTech or Moderna vaccines: a modified adenovirus that sparks an immune system response against COVID-19, rather than mRNA technology that "trains" the immune system to identify and attack the COVID-19 virus. While all three vaccines are effective at preventing COVID infection, the J&J shot only offers 72% efficiency in the U.S. compared to the above 90% offered by either Pfizer-BioNTech or Moderna regimen.
The study was designed to explore the possible advantages or downsides to different vaccine and booster regimens, with researchers hoping that mixing-and-matching different vaccine platforms would offer broader protection against not only the original virus strain, but its variants too.
Study volunteers were divided into groups, each receiving either a booster shot of their original vaccine or one from a different company. From there, antibody levels were measured two weeks and four weeks after the boosters were given.
The study found that all possible vaccine combinations boosted antibody levels higher, but the mRNA-based vaccines developed by Pfizer-BioNTech and Moderna demonstrated the highest levels, with participants who received those vaccines having a higher antibody response more often than those who received an extra dose of the J&J vaccine. Moreover, the study showed that participants who originally received the J&J vaccine appear to have a better immune response if they were boosted by Pfizer-BioNTech or Moderna.
The study also showed that there were no serious side effects with mixing-and-matching vaccines.
"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 vaccine regimen," NIH researchers wrote in the study, which has yet to be peer reviewed. "Heterologous prime boost strategies may offer immunological advantages to optimize the breadth and longevity of protection achieved with currently available vaccines."
More than 15.3 million Americans have received J&J's one-dose COVID vaccine regimen, according to data compiled by the U.S. Centers for Disease Control and Prevention, compared to the over 104.5 million and 69.5 million inoculated with Pfizer-BioNTech's and Moderna's regimens, respectively.
