The effectiveness of the currently available COVID-19 vaccines plunged to near zero within months, according to U.S. Centers for Disease Control and Prevention (CDC) data presented on June 5.
Estimated shielding among adults aged 18 to 64 against visits to emergency departments and urgent care facilities turned negative beyond 120 days after peaking at 52 percent, an analysis of data from the CDC’s VISION network found. Protection for those 65 and older was pegged at 9 percent 120 days and later following receipt of one of the vaccines, after peaking at 47 percent.
Shielding against hospitalization was estimated to peak at 31 percent and drop to 4 percent beyond 120 days among adults aged 18 to 64 and peak at 53 percent before plunging to 16 percent among adults aged 65 and up, according to data from the network.
The protection against admission to an intensive care unit or death was slightly higher, grouped together under the critical illness designation by CDC officials, coming in at 32 percent beyond four months.
Data from another CDC network, IVY, showed that effectiveness against hospitalization declined to 27 percent among adults beyond 90 days, and even lower—to 23 percent—during the period of time after JN.1 and its lineages became the dominant strains in the United States in late 2023.
Protection against symptomatic infection was just 37 percent after 60 days during the time of JN.1 dominance, according to data from a third CDC network.
The only estimates for children, from VISION, also showed sharp waning. The shielding against visits to emergency departments or urgent care facilities started at 65 percent for children aged 9 months to 4 years, and 71 percent for children aged 5 to 17, but plunged after 60 days to 13 percent for the younger group and 48 percent for the older group, according to the presentation. No estimates for hospitalization among children were provided.
“Waning patterns appeared similar to previous COVID-19 vaccine formulations, with the most durable protection appearing to be for critical illness,” said Dr. Ruth Link-Gelles, the CDC official who presented the data to a U.S. Food and Drug Administration (FDA) committee.
She added later: “We do continue to see waning of vaccine effectiveness. Because that’s inextricably linked with time, as with the new variants, it’s difficult to parse out how much of loss of effectiveness over time is due to waning versus new variants.”
The currently available COVID-19 vaccines, made by Pfizer-BioNTech, Moderna, and Novavax, were cleared in 2023 and target the XBB.1.5 virus variant. That strain was displaced in late 2023 and now causes virtually no cases.
The advisory committee is considering whether to recommend the FDA direct vaccine manufacturers to update the formulations of the shots yet again, in a bid to counter the effectiveness issues.
FDA staffers ahead of the meeting said that the shots should be updated because there had been “a decrease in effectiveness of COVID-19 vaccines (2023-2024 Formula) against COVID-19 caused by JN.1 lineage viruses.”
Some non-CDC papers have pegged vaccine effectiveness as starting low and dropping quickly, including a study from English researchers that found the currently available vaccines provided just 26.4 percent protection against hospitalization from five to nine weeks following vaccination.
The updated shots will likely target JN.1 or KP.2, which is a JN.1 lineage.
The World Health Organization and European health authorities have already advised updating COVID-19 vaccines to target JN.1.
Officials with Pfizer, Moderna, and Novavax agree with the efforts to update the formulations, according to presentations set to be made to the FDA’s advisory committee later on Wednesday.
The companies said that testing in animals showed that shots containing JN.1 triggered strong antibody responses to JN.1 and its sublineages.
Moderna officials said they would complete a small, open-label trial among humans in the fall if its shot is approved.
Initial shipments of a Novavax vaccine targeting JN.1 are on track to be in U.S. warehouses in August, the company said. Moderna and Pfizer officials also said they could produce vaccines by August.
According to CDC surveys, just 14 percent of children, and 22.5 percent of adults, have received one of the currently available vaccines.
U.S. authorities say the COVID-19 vaccine campaign has fully transitioned to a model that updates the shots on a yearly basis and attempts to administer the vaccines to many Americans in the fall and winter to try to curb the spread of the virus.
While there’s no established correlative marker of protection, companies have during the COVID-19 pandemic turned to neutralizing antibodies as the primary way to predict effectiveness.
Some scientists say vaccines that can produce high levels of antibodies against COVID-19 will do well.
“I think it’s a very well established conundrum in the field that we are still seeking a correlate of protection,” Dr. Kayvon Modjarrad, a Pfizer official, told the meeting. “With respect to what justifies a sufficient antigenic difference, several cycles of vaccine updates have shown that more closely matched vaccines to circulating variants elicit better immunity and protection against COVID-19. … We saw that translated to improved clinical effectiveness, and we expect the same here.”