US Boosts Investment in Avian Flu Vaccine Candidates – Medscape

Two large US investments in human vaccines for avian influenza A(H5N1) are aimed at boosting US readiness in the case of a pandemic.

Last week, the US Department of Health and Human Services (HHS), through the Biomedical Advanced Research and Development Authority, announced it will pay Moderna $176 million to develop an mRNA-based pandemic influenza vaccine.

The announcement came weeks after the government ordered 4.8 million doses of a pre-pandemic cell-based vaccine, well matched to the currently circulating H5N1 strain, according to the manufacturer, CSL Seqirus. The doses are expected to be available next week for the US National Pre-Pandemic Influenza Vaccine Stockpile.

The cell-based vaccine would need to be approved by the US Food and Drug Administration (FDA) before any potential distribution.

A spokesperson for the Administration for Strategic Preparedness and Response (ASPR) told Medscape Medical News, "ASPR has hundreds of thousands of doses that could be deployed within weeks pending regulatory approval by the FDA and is filling approximately 4.8 million additional doses to augment this reserve."

Moderna has started its phase 1/2 trial to test the safety of its investigational pandemic influenza vaccine (mRNA-1018) in healthy adults. The study includes antigens against the H5 and H7 avian flu viruses. Results are expected later this year, Moderna said in a press release. According to the company, the $176 million in funding will support the late-stage development of the vaccine.

Dawn O'Connell, assistant secretary for preparedness and response at HHS, said Moderna's phase 3 trials could begin in 2025. She said the funding agreement allows the government to shift quickly to supporting the development of other versions of the mRNA vaccines when new viral strains emerge.

The Centers for Disease Control and Prevention (CDC) maintains that the avian flu risk to humans remains low. "No segment of the population has been recommended for vaccination," the ASPR spokesperson noted.

But in the CDC's most recent update, the agency said, "This is a rapidly changing situation" and posted interim recommendations for prevention, monitoring, and public health investigations of avian flu virus infections in people.

A fourth case of cow-to-human transmission was reported on July 3, this time in Colorado. Three previous human cases were reported in farmworkers in Texas and Michigan. There have been 145 confirmed cases in livestock herds in 12 states.

The two kinds of vaccine work in different ways. The cell-based version grows the influenza virus in a cell culture, and the virus is then inactivated, purified, and used as the vaccine antigen.

Rather than using a part of an actual virus, Moderna's vaccines use mRNA that codes for viral antigens. The body's own cellular machinery then creates those antigens, which induce the immune system to generate antibodies that will recognize them on the virus. Once cells finish making a protein, they quickly break down the mRNA.

With the two vaccines soon to be available is needed, HHS Secretary Xavier Becerra said the country is well prepared for a potential pandemic. "We have successfully taken lessons learned during the COVID-19 pandemic and used them to better prepare for future public health crises. As part of that, we continue to develop new vaccines and other tools to help address influenza and bolster our pandemic response capabilities," he said in a statement. "Importantly, we are doing this work in partnership with some of the nation's leading scientists and clinicians."

No relevant financial relationships were disclosed.

Marcia Frellick is a freelance journalist based in Chicago. She has previously written for the Chicago Tribune, Science News, Northwestern magazine, and Nurse.com and was an editor at the Chicago Sun-Times, Cincinnati Enquirer, and St. Cloud Times. Follow her on X: @MLfrellick.

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US Boosts Investment in Avian Flu Vaccine Candidates - Medscape