The bird flu vaccine is made from eggs. This worries scientists.

Even news about a new flu pandemic is enough to make scientists laugh about eggs.

They were worried about them in 2005 and 2009, and they are still worried today. Indeed, millions of fertilized chicken eggs are still the main ingredient in making vaccines that will hopefully protect people against the outbreak of a new strain of flu.

“It’s almost comical to use technology from the 1940s for a 21st century pandemic,” said Rick Bright, who led the Department of Health and Human Services’ Biomedical Advanced Research and Development Authority under the Trump administration.

It’s not so funny, he says, when the wording currently stored against the H5N1 bird flu virus requires two injections and 90 micrograms of antigen, but provides only moderate immunity. “In the United States alone, it would take chickens to lay 900,000 eggs every day for nine months,” Bright said.

And that’s only if the chickens are not infected.

The spread of the avian flu virus has decimated flocks of birds (and dead barn cats And other mammals). Cattle in at least nine states and at least two people in the United States have been infected, enough to once again focus public health attention on the potential for a global pandemic.

So far the only confirmed human cases cases of infection included dairy workers in Texas and Michigan, both of whom suffered from conjunctivitis and quickly recovered. Still, the spread of the virus to multiple species over a wide geographic area raises the threat that new mutations could create a virus that spreads from human to human through airborne transmission, causing respiratory infections.

If so, prevention starts with the egg.

To make the raw material for a flu vaccine, the virus is grown in millions of fertilized eggs. Sometimes it doesn’t grow well, or it mutates to such an extent that the vaccine product stimulates antibodies that don’t neutralize the virus – or the wild virus mutates to such an extent that the vaccine no longer works against it. And there is still the frightening prospect that wild birds could carry the virus into the chicken coops needed for vaccine production.

“Once those roosters and hens die, you don’t have any vaccine left,” Bright said.

Since 2009, when an H1N1 swine flu pandemic swept the world before vaccine production could begin, researchers and governments have sought alternatives. Billions of dollars have been invested in vaccines produced from mammalian and insect cell lines that do not pose the same risks as egg-based shots.

“Everyone knows that cell-based vaccines are better, more immunogenic and have better production,” said Amesh Adalja, an infectious disease specialist at the Johns Hopkins University Center for Health Security. “But they are handicapped because of the weight of egg-based manufacturing.”

The companies that make cell-based flu vaccines, CSL Seqirus and Sanofi, have also invested billions in egg-based production lines that they are not eager to replace. And it’s hard to blame them, said Nicole Lurie, HHS assistant secretary for preparedness and response under President Barack Obama, now executive director of CEPI, the global nonprofit against the epidemic.

“Most vaccine manufacturers who responded to an outbreak — Ebola, Zika, COVID — ended up losing a lot of money,” Lurie said.

The exceptions were the mRNA vaccines created for COVID, although even Pfizer and Moderna had to destroy hundreds of millions of unwanted vaccine doses as public interest waned.

Pfizer and Moderna test seasonal flu vaccines made with mRNAand the government is soliciting proposals for mRNA pandemic flu vaccines, said David Boucher, director of infectious disease preparedness at HHS’s Administration for Strategic Preparedness and Response.

Bright, whose agency invested $1 billion in a cell-based flu vaccine factory in Holly Springs, North Carolina, said there was “no chance we could fight a H5N1 pandemic with an egg-based vaccine. But for now, there is little choice.

BARDA has stockpiled hundreds of thousands of doses of an H5N1 strain vaccine that stimulates the creation of antibodies that appear to neutralize the virus currently circulating. It could produce millions more doses of vaccine in a matter of weeks and up to 100 million doses in five months, Boucher told KFF Health News.

But the vaccines currently in the national stockpile do not perfectly match the strain in question. Even with two shots containing six times more vaccine substance than conventional flu vaccines, the stored vaccines were only partially effective against the strains of the virus that were circulating when those vaccines were manufactured, Adalja said.

However, BARDA is currently supporting two clinical trials with a vaccine virus candidate that “matches well with what we found in cows,” Boucher said.

Flu vaccine manufacturers are just beginning to prepare the shots for this fall but, ultimately, the federal government could request that production be transferred to a strain targeted against the pandemic.

“We don’t have the capacity to do both,” Adalja said.

For now, ASPR has a bulk stockpile of pandemic vaccines and has identified manufacturing sites where 4.8 million doses could be bottled and finished without stopping production of seasonal flu vaccine, said ASPR leader Dawn O’Connell on May 22. away from egg-based vaccines in 2005, when avian flu first hit the world, and with increased vigor after the fiasco of 2009. But “with the resources we have, we get the best value “price and best value for American taxpayers when we operate seasonal infrastructure, and that remains primarily egg-based,” Boucher said.

Flu vaccine manufacturers “have a system that is working well right now to meet their seasonal vaccine manufacturing goals,” he said. And without financial incentive, “we’re going to be here with eggs for a while, I think.”

KFF Health News is a national newsroom that produces in-depth journalism on health issues and is one of the major operating programs of KFF — the independent source for health policy research, polling and journalism.


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