This fall’s COVID-19 vaccine should target the XBB.1.5 variant and for the first time not take aim at the original virus, a federal advisory committee recommended Thursday.
The vaccine’s protection against infection fades over time, and the virus has changed enough that if there’s another outbreak this fall or winter, as there has been the last three years, many people will not be well protected, experts told the committee.
The best way to prevent infections will be to reconfigure the vaccine to target an XBB variant, officials said during the day-long Vaccines and Related Biological Products Advisory Committee meeting.
Since earlier this year, the XBB-lineage has dominated infections across the United States and the world, starting with XBB.1.5 and now, seemingly evolving toward XBB.1.16 and XBB.2.3.
Government officials and vaccine manufacturers said data shows targeting an XBB variant will provide better protection than current shots. Targeting more than one variant isn’t necessary, they said, because the current XBB variants are so similar.
Three manufacturers, Pfizer-BioNTech, Moderna and Novavax, can all make XBB vaccines widely available in September, they said. The World Health Organization and the European Union are also looking at XBB vaccination, simplifying global supplies.
Why no bivalent vaccine this time?
Last year, the vaccine was changed to target both the original variant and the BA.4/BA.5 variants, but data shows this so-called bivalent vaccine has lost effectiveness against the current variants.
The original Wuhan variant has not been in circulation since 2021 and so no longer needs to be part of the vaccine, experts told the panel. Wuhan was included in the current vaccine because protection against it seemed to also work against other variants, but that protection has waned as the virus drifted from its origins.
The current pace of change suggests that XBB.1.6 will be the dominant variant in the U.S. by the fall, but that XBB.2.3 and other XBB sublineages could continue to increase. The three variants do not differ much in their spike protein, which is the target of the vaccines, so a vaccine targeting any should be effective against all three, experts told the panel.
All three companies have examined the impact of vaccines targeting all three XBB variants and found that one aimed at XBB.1.5 appears to be most protective. The safety profiles are unchanged.
The committee’s decision still needs to be ratified by the FDA commissioner. Another panel of outside experts will consider how the vaccine should be used, and the director of the Centers for Disease Control and Prevention will need to ratify their decision.
With the current vaccine providing only limited effectiveness, FDA officials promised to talk with their counterparts at the CDC about encouraging people to wait for the new vaccines to become available before they get boosted again.
What about boosters for older people?
It also remains unclear whether healthy people under the age of about 70 or 75 will need regular boosters. Data from several studies suggests that although so-called neutralizing antibodies against the virus fade within four to six months of vaccination, another arm of the immune system, called T cells, continue to provide protection against severe disease.
Since only immunocompromised and older people are at high risk for severe disease if infected, they stand to benefit the most from repeated boosting.
But studies do show that several boosters provide more protection than a single shot and that a combination of infection and vaccinations provides even better protection. According to the WHO, about 90% of people worldwide have been infected with SARS-CoV-2, the virus that causes COVID-19.
About 95% of Americans over 50 have received at least one vaccine dose, with lower levels among younger people: 82% of those over 18, 72% of those 12-17, 40% of children 5-11, 11% of those 2-4 and 9% of those under 2.
Children were less likely to need emergency care for COVID-19 if they were vaccinated, according to a study released this week by Epic Research. Although hospital visits were rare for children of all ages, for those aged six month to four years, vaccination reduced the risk of a COVID-related ER visit by 80%.
Contact Karen Weintraub at kweintraub@usatoday.com.
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