The US Is Loading Up on Bird Flu Vaccine

Amid a US outbreak of avian influenza in poultry flocks and dairy cattle, the federal government on Friday announced $72 million in funding to three vaccine manufacturers to expand the production of bird flu vaccines for humans, in the event that they are needed.

The H5N1 virus has affected millions of wild and commercial birds nationwide, and in March it made the jump to dairy cows for the first time. As the number of affected animals grows, so does the concern for spread to people. In the past, H5N1 has had a high mortality rate in humans, and scientists are monitoring the virus closely to determine whether it poses a pandemic risk. The US government has a stockpile of approved H5N1 vaccines, but today’s awards, which will go to CSL Seqirus, GSK, and Sanofi, will double that number.

“We do expect that we will have a total of just over 10 million doses filled and finished by the end of the first quarter of calendar year 2025,” said David Boucher, director of infectious disease preparedness and response at the Administration for Strategic Preparedness and Response, in a press briefing on Friday.

Moderna, Pfizer, and GSK are also working on mRNA vaccines for bird flu, but those need to go through human testing and be approved by the US Food and Drug Administration before they could be used.

This year, 16 people in the US have been infected with bird flu. The US Centers for Disease Control and Prevention confirmed the latest two cases, both in California, Thursday evening. The individuals are farm workers who had contact with infected dairy cows at two facilities in the Central Valley, the epicenter of the state’s cattle outbreak. Both had mild symptoms, including eye redness, and are being treated with antiviral medication. Neither reported respiratory symptoms or were hospitalized.

Nirav Shah, the CDC’s principal deputy director, said the new cases do not change the agency’s risk assessment for the general public, which continues to be low. “Finding these two cases was not unexpected,” he said during Friday’s briefing. “As there are more herds that test positive, there are more workers who are exposed, and where there are more workers who are exposed, the chances of human infection increase.”

Both California cases are thought to be instances of animal-to-human spread, with no known link or contact between the two. California health officials are following up with close contacts of the workers, including household members that are also dairy workers.

In the coming days, the CDC says it will do additional testing on the virus samples, including genetic sequencing to monitor for any changes in the virus. Scientists are particularly interested in whether the virus is developing new mutations that could make human-to-human transmission more likely. The agency says there is no evidence that the virus can spread from person to person at this time.

Of the 16 confirmed human cases, six have been linked to exposure to sick or infected dairy cows, while nine had exposure to infected poultry. The source of infection for a case in Missouri has not been determined.