After the September authorization by BioNTech of a third Pfizer / Johnson & Johnson shot, the Food and Drug Administration approved booster doses of Moderna and Johnson & Johnson COVID-19 vaccinations.
Today, the agency announced that mix-and-match boosters will be available to eligible persons who have been fully vaccinated. This means that anyone can receive a booster dose for any of the vaccines regardless of their original vaccination.
The FDA approved third Moderna shots, just like the BioNTech booster and Pfizer, for vulnerable populations, such as people 65 and older, people at high risk for severe disease and those at high risk of COVID-19 exposure at work.
However, the booster for Moderna will only be available in a half-dose. Both vaccines contain small amounts of coronavirus genetic material. Moderna vaccine contains 100 micrograms of the coronavirus genetic material, while the BioNTech shot has 30 micrograms. According to the company, a third, 50-microgram dose of Moderna vaccine could cause less side effects and still provide strong protection.
Moderna shots provide a longer-lasting protection against COVID-19 infection than the Pfizer/BioNTech shots. They also last for months, whereas the effectiveness of the Pfizer/BioNTech shots seems to decrease. Both offer strong protection against death and hospitalization.
Everyone who received the Johnson & Johnson vaccine will be able to receive a second booster dose from the FDA. Boosters for Johnson & Johnson vaccine are available two months after the initial dose. This is in contrast to the six-month wait required for Moderna or BioNTech boosters.
Boosters for Johnson & Johnson vaccine may be started two months after the initial dose. This is in contrast to the six-month wait required for Moderna or BioNTech boosters.
Johnson & Johnson shot was initially authorized as a single shot vaccine. Experts hoped this would make it easier to deliver the vaccine to low-resource areas, and also to give the shot to people who might not be interested in a second shot. Despite this, the vaccine has been administered to only 15 million Americans.
Johnson & Johnson's vaccine inserts a portion of the coronavirus gene in an adenovirus virus. This delivers the gene to the body's cells. Although it was successful in initial clinical trials, experts were confident that it would protect. However, its results weren't as strong or as those of the Moderna and BioNTech shots. A recent Centers for Disease Control and Prevention study found that a single Johnson & Johnsons vaccine shot was only 71% effective in preventing hospitalization. This is lower than the protection from hospitalization provided by the mRNA vaccines. The data also shows that those who received that vaccine were more likely to develop breakthrough infections than those who received gene-based shots.
Johnson & Johnson claims that a second booster dose increases the vaccine's effectiveness against COVID-19 symptomatic cases to 94 percent. This is consistent with initial clinical trials results for gene-based shots. Even though the FDA approved the booster, it was critical of Johnson & Johnson's initial assessment of the need for a booster. According to the FDA, the test that was used to measure antibody levels in patients who received a second dose of vaccine wasn't sensitive enough.
People who received the Johnson & Johnson shot today have more options than simply getting a second shot. The FDA's decision to allow mix-and-match boosters may help these people have stronger antibody responses. Federally funded research showed that boosting with an mRNA vaccination generates more antibodies in that group than boosting with a second Johnson & Johnson shot.
The antibody levels of people who received either the mRNA vaccine for their first shot or a different one for their boosters were similar. The study found that mixing and matching was safe.
Mixing and matching was safe
This data is consistent in research from the United Kingdom where people have been mixing AstraZeneca CoVID-19 vaccine (which has not been used in the US but works the same way as the Johnson & Johnson shot), with the Pfizer / BioNTech shot over many months. Studies have shown that one shot of either produces as much or more antibody than two shots of either.
This is all subject to a caveat. These studies only measured antibody levels and did not provide real-world protection against disease. Since other immune cells are responsible for preventing severe illness, it is important to continue research on how the different mixing regimens prevent COVID-19.
Peter Marks, Director of FDA's Center for Biologics Evaluation and Research said that they will continue to collect additional data as soon as possible in order to assess the risks and benefits of booster doses in other populations. He also stated that he plans to inform the public and healthcare community about our decision in the coming weeks.
