Updated COVID-19 Vaccines Needed Due to Waning Effectiveness: FDA

The U.S. Food and Drug Administration in White Oak, Md., on July 20, 2020. Sarah Silbiger/Getty Images

Newly formulated COVID-19 vaccines are necessary because the performance of the current slate is slipping over time, U.S. officials said this week.

“There appears to be an inverse relationship between the time since vaccination and vaccine effectiveness, such that bivalent COVID-19 vaccine effectiveness against Omicron sublineages appears to wane over time,” Food and Drug Administration (FDA) officials said.

The vaccines were already updated in late 2022 to focus on Omicron subvariants such as BA.5, with the hope they would perform better than the old vaccines.

But the shots have been providing subpar protection against infection and short-lived shielding against hospitalization, according to data from the United States and elsewhere. That prompted a partial rollback in the availability of the shots.

Protection against hospitalization for adults aged 18 to 65 who are described as immunocompetent, for instance, started at 68 percent but plunged to 27 percent beyond 60 days, according to data from the U.S. Centers for Disease Control and Prevention.

Other papers suggest the levels of neutralizing antibodies—believed to help protect people against COVID-19—induced by the vaccines against XBB and its sublineages are lower than the levels against BA.5, the FDA staffers noted. Some evidence indicates that the bivalents, which retained a component of the original Wuhan strain, perform better against that variant, which hasn’t been in circulation since 2020.

Those three points prompted the officials to say they’re preparing to direct vaccine makers to produce updated vaccines that don’t contain a Wuhan component.

“Both real-world evidence and immunogenicity data suggest that a vaccine composition that more closely matches circulating virus strains can significantly improve vaccine-induced immunogenicity and protection,” the officials said.

They provided no citations and the FDA didn’t return a request for comment.

A summary of a recent meeting with other regulators offered a different statement that did not mention real-world data. It said that “preclinical data show that a vaccine composition that more closely matches currently circulating strains improves immunity.”

The document (pdf) was released ahead of the FDA’s June 15 meeting with its panel of vaccine advisers.

The group will consider the next composition of the vaccines, with an eye toward a fall/winter booster campaign.

What to Target?

The FDA and other regulators, including some from Europe, convened in May to discuss how to move forward as they move to implement a model for COVID-19 vaccination similar to the one for the influenza vaccines.

They converged on the proposal for the next round of vaccines to target XBB, a parent lineage stemming from BA.2 sublineages, and its descendants, given that they are now dominant in the United States and many other countries.

Officials also said that monovalent vaccines would be better in light of the high levels of prior vaccination and/or infection in many countries.

“The addition of prior circulating variants or lineages is not likely to provide further benefit,” a summary of the meeting stated.

The World Health Organization plans to meet twice a year to review evidence and recommend either to keep the current vaccines in circulation or to update them. After a meeting in May, the organization recommended updating the vaccines to target XBB lineages.

The XBB lineages may be gone, though, by the time updated vaccines are available.

“All of these have overlapping degrees of susceptibility to vaccines tailored to one of them. But by January 2024, when a new wave would start up, if the virus is seasonal—and that is a big if, we don’t know it yet but this winter we should see better—then a booster tailored to any of these three may very well be out of date and perform poorly for reducing severity of illness,” Dr. Harvey Risch, professor emeritus of epidemiology at the Yale School of Public Health, told The Epoch Times via email.

Uncertainty, and Lack of Data

Health authorities have acknowledged that little data exist as they chart the way forward.

“Data on the immune response specific for XBB.1 descendent lineages are largely restricted to neutralizing antibodies and are limited for other aspects of the immune response, including cellular immunity,” the World Health Organization said.

The FDA said that the evolution of COVID-19 “is complex and remains unpredictable.”

Officials in the United States and elsewhere already cleared in 2022 the currently available shots with no clinical trial data, saying they believed, but could not confirm, that the shots would perform better than the previously available ones.

The indications are now that the vaccine makers will not be required to run trials on the updated compositions.

FDA officials said that vaccine manufacturers have been conducting human serology studies on the current vaccines against the XBB lineages, and preclinical immunogenicity studies on new vaccine candidates, but none of the data from the studies were included in the document or have yet been released to the public. The FDA said that the data will be presented during the meeting by the companies.

Only three companies have vaccines available in the United States: Pfizer, Moderna, and Novavax. Johnson & Johnson’s vaccine was pulled from the market earlier this year.