As bird flu outbreaks spread among birds and mammals, the U.S. government says it has three FDA-approved H5N1 vaccines in its stockpile. However, experts questioned the effectiveness against current strains and raised concerns about potential side effects.
Federal officials said they supply several hundred thousand doses within weeks and 10 million more using materials on hand, and expect to produce 125 million doses within four months.
Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, suggested the agency has a “pretty low threshold” to deploy the stockpiled vaccines.
“We believe that, if we needed to, [our vaccines] would be reasonably good matches,” Marks said on April 1 at the World Vaccine Congress in Washington, D.C.
Given that all stockpiled vaccines were made for an earlier strain of H5N1, it’s uncertain how effective they would be against the strains that are circulating now, former FDA scientist Luciana Borio told STAT News.
“The FDA-approved H5N1 vaccines — licensed in 2013, 2017, and 2020 — do not elicit a protective immune response after just one dose,” Borio said. Even after two doses, “It is unknown whether the elicited immune response is sufficient to protect against infection or severe disease.”
A spokesperson for the U.S. Department of Health and Human Services’ Administration for Strategic Preparedness and Response (ASPR) program told Barron’s the agency could “ramp up production to make enough vaccine doses to vaccinate the entire U.S. population.”
A portion of the stockpile consists of “chunks” of premade antigens — good for training the immune system against specific strains — and adjuvants, the ingredients used to activate the human immune system when vaccines are administered.
However, despite its assurances of rapid vaccine delivery, ASPR did not detail its plans beyond claiming it could vaccinate about 68 million people, or one-fifth of the country’s population — using the two-dose regimen — within four months of an outbreak.
Internist and epidemiologist Dr. Meryl Nass, appearing with James Corbett on the April 20 episode of “Good Morning CHD,” said, “You’ve got a dangerous vaccine for a nothing disease,” noting the low number of human H5N1 cases reported thus far.
“It’s supposedly for a life-threatening illness,” she said. “Of course, pink eye is not life-threatening,” she said.
“The whole purpose of bird flu is to make you think the pandemics are out there, they’re coming for you all the time, and you need them [the health bureaucracy] to save you,” Nass said.
Sanofi vaccine contains thimerosol, PEG
Sanofi’s H5N1 vaccine, approved for adults in April 2007, was developed from a virus strain isolated from a Vietnamese patient in 2004.
“Our egg-based vaccine supply would well contribute to support a global influenza pandemic response should it arise either from A/H5N1 or any other influenza strain,” a Sanofi spokesperson told MedPage Today.
Each 90 microgram (µg) dose includes influenza virus hemagglutinin, 500 milligrams (mg) of porcine (pig) gelatin and approximately 98 µg of thimerosal, a mercury derivative (equaling approximately 50 µg of mercury/dose).
Other ingredients used in the development of the vaccine include embryonated chicken eggs, formaldehyde, polyethylene glycol and sugar.
Polyethylene glycol, or PEG, has been linked to the anaphylactic reaction in the COVID-19 vaccines.