A U.S. Centers for Disease Control and Prevention (CDC) advisory panel is due on Tuesday to recommend whether the updated COVID-19 shots formulated by vaccine manufacturers should be given broadly or just to specific populations at higher risk during this fall's vaccination campaign.
The updated shots are part of a push by public health officials to align the next COVID vaccines more closely with the actual circulating variant of the virus, similar to the way annual flu shots are designed.
The U.S. Food and Drug Administration (FDA) on Monday authorized updated COVID vaccines made by Pfizer (PFE.N) and its German partner BioNTech SE (22UAy.DE) as well as by Moderna (MRNA.O). Novavax (NVAX.O) said the FDA was still reviewing its shot.
Keeping up with the latest variants of the ever-evolving coronavirus has been a challenge for public health officials globally since the pandemic began in 2020, with some possessing more worrisome characteristics than others. Vaccines can be formulated to target specific variants. The variants circulating the most widely in the United States right now are subvariants of what is called the XBB lineage of the virus.
The meeting of the CDC advisers was set to start at 10 a.m. ET (1400 GMT). At issue is whether the advisers will call for targeting specific populations for the new boosters - such as older adults or people with underlying medical conditions - or a campaign with the broader population in mind.
"I do think that a broad boosting strategy makes sense," said Caitlin Rivers, a senior scholar at the Johns Hopkins Center for Health Security in Baltimore, adding that while the virus was not causing as many hospitalizations and deaths as before, it is still circulating.
COVID infections and hospitalizations have been rising in the United States, Europe and Asia but remain well below previous peaks. U.S. deaths are now relatively low - reported at around 2,000 last month - though the country has experienced 1.1 million COVID deaths since the outset of the pandemic.
"The one group that I am curious to hear the committee's recommendation on is young men, because we do see that, in rare cases, young men can develop myocarditis or related effects," Rivers said, referring to a rare condition in which inflammation develops in the middle muscular layer of the heart wall.
The first COVID vaccines in 2020 were monovalent, or single-target vaccines, aimed at the original strain of the virus. They were followed by bivalent COVID vaccine booster shots that targeted both the original and the Omicron strains. The new updated shots are again monovalent, targeting what is called the XBB.1.5 variant, as requested by the FDA.
"I do think that the XBB.1.5 vaccine will provide better cross protection against the current Omicron variants than the bivalent booster," said Dr. Daniel Kuritzkes, chief of infectious diseases at Brigham and Women's Hospital in Boston.
Scientists are also closely watching other Omicron subvariants that are circulating, including the currently dominant EG.5, nicknamed Eris, and the highly mutated BA.2.86 subvariant, that had raised concerns about a resurgence of infections.
Kuritzkes said there will be some cross-protection across variants from the updated shots.
"It's obviously not the same as giving a shot of whatever the most prevalent current variant is, but that is almost an impossibility, given the speed with which the virus has been evolving," Kuritzkes said.
Vaccine makers Pfizer/BioNTech, Moderna and Novavax have said their updated shots are effective in protecting against the EG.5 subvariant, while Moderna and Pfizer's shots generated strong responses in testing against the BA.2.86 subvariant. Novavax said on Monday it was still testing its vaccine against BA.2.86.
