A recent study evaluating the bivalent booster in people over the age of 12 showed that it worked equally well in individuals of all ages. The researchers compared three months after people received a bivalent booster (September to December 2022) with those during three months after receiving a monovalent booster (May to August 2022). They found that the monovalent booster was 25 percent effective in preventing hospitalization or death, while the bivalent booster was 62 percent effective.
Although the boosters worked for everyone, experts say that because older adults are more likely to be hospitalized for COVID-19, they would experience greater benefits. “Even if the effectiveness is similar, the boost is more important in older people because their absolute risk is higher,” said Danyu Lin, professor of biostatistics at the University of North Carolina at Chapel Hill.
Also encouraging was a CDC study looking at whether a bivalent booster protects against infection in people ages 18 to 49. Compared to people who received two to four doses of the original vaccine, those who received a bivalent booster were about 50 percent less likely to develop symptomatic infection from BA.5 or XBB/XBB.1.5.
However, like the original vaccine, the bivalent booster slightly increases the risk of myocarditis, an inflammation of the heart muscle, in people 18 to 35 years of age. As a result, some experts are hesitant to recommend more booster doses to this group.
“If you’re young, let’s say you’re 35, 40, you’re otherwise healthy, you’ve already been vaccinated and boosted and probably had an infection or two in the past, I think that the person is fairly well protected for some time,” said Dr. David Ho, professor of medicine at Columbia University, who led one of the antibody studies. “Until more data is available, I would Will not force you to get annual vaccinations.”
What will boosters look like in the months and years to come?
The FDA has suggested that, for most Americans, boosters can be given annually in the fall, like the flu vaccine, and that high-risk individuals can still receive multiple doses a year. It is unclear when, or if, it will formally recommend this approach.
Dr. Lin has conducted unpublished research that compared outcomes to the number of booster doses people receive per year. Their data shows that people who get less than one booster a year, on average, have higher rates of hospitalization and death than people who get one or more doses. There is little difference between one and more than one booster dose per year. He said this suggested that an annual booster was sufficient for most people; However, for older adults, even the small benefit gained from multiple boosters a year is probably worthwhile.