O bird flu The outbreak in US dairy cows is leading to the development of new next-generation mRNA vaccines – similar to COVID-19 shots – that are being tested in animals and people.
Next month, the U.S. Department of Agriculture will begin testing a vaccine developed by researchers at the University of Pennsylvania by administering it to calves. The idea: If vaccinating cows protects dairy workers, that could mean less chance of the virus spreading to people and mutating that could encourage human-to-human spread.
About that. The U.S. Department of Health and Human Services has been talking to manufacturers about possible mRNA flu vaccines for people that, if necessary, could supplement millions of doses of bird flu vaccine already in the government’s hands.
“If there is a pandemic, there will be a huge demand for a vaccine,” said Richard Webby, a flu researcher at St. Jude Children’s Research Hospital in Memphis. “The more different (vaccine manufacturing) platforms that can respond to this, the better.”
The bird flu virus has spread among more animal species in several countries since 2020. It has been detected in US dairy herds in March, although investigators believe it may have occurred in cows as early as December. This week, the USDA announced that it had been found in alpacas for the first time.
At least three people – all workers on farms with infected cows – were diagnosed with bird flu, although the illnesses were considered mild.
But earlier versions of the same H5N1 flu virus were highly lethal to humans in other parts of the world. Authorities are taking steps to be prepared in case the virus mutates that makes it more deadly or allows it to spread more easily from person to person.
Traditionally, most flu vaccines are produced using an egg-based manufacturing process that has been used for more than 70 years. It involves injecting a candidate virus into fertilized chicken eggs, which are incubated for several days to allow the virus to grow. The fluid is harvested from eggs and used as a base for vaccines, with dead or weakened viruses stimulating the body’s immune system.
Instead of eggs – also vulnerable to supply constraints caused by bird flu – some flu vaccines are produced in giant vats of cells.
Officials say they already have two vaccine candidates for people that appear to be a good match for the avian flu virus in U.S. dairy herds. The Centers for Disease Control and Prevention used the circulating bird flu virus as the seed strain for them.
The government has hundreds of thousands of vaccine doses in syringes and prefilled vials that could likely go out in a matter of weeks if needed, federal health officials say.
They also claim to have bulk antigen that could generate nearly 10 million more doses that could be filled, finished and distributed in a matter of a few months. CSL Seqirus, which makes cell-based flu vaccine, announced this week that the government hired to fill and finish approximately 4.8 million of these doses. The work could be completed by the end of the summer, U.S. health officials said this week.
But flu vaccine production lines are already working on this fall’s seasonal vaccines — work that would have to be halted to produce millions more doses of bird flu vaccine. Therefore, the government has followed another, faster approach: the mRNA technology used to produce the primary vaccines used against COVID-19.
These messenger RNA vaccines are made from a small section of the virus’s genetic material. The genetic blueprint was designed to teach the body how to produce a protein used to build immunity.
The pharmaceutical company Moderna already has an mRNA vaccine against bird flu in the initial phase of human testing. In a statement, Moderna confirmed that “we are in discussions with the US government about advancing our pandemic influenza candidate.”
Similar work is being carried out at Pfizer. The company’s researchers in December gave human volunteers an mRNA vaccine against a strain of bird flu that is similar to — but not exactly the same as — that in cows. Researchers have since conducted a laboratory experiment exposing blood samples from those volunteers to the strain seen on dairy farms and observed “remarkable increases in antibody responses,” Pfizer said in a statement.
As for the vaccine for cows, Penn immunologist Scott Hensley worked with mRNA pioneer and Nobel Prize winner Drew Weissman to produce the experimental doses. Hensley said the vaccine is similar to Moderna’s for people.
In the first stage of the test, mice and ferrets produced high levels of antibodies that fight the bird flu virus after vaccination.
In another experiment, researchers vaccinated a group of ferrets and deliberately infected them, then compared what happened to ferrets that hadn’t been vaccinated. All of the vaccinated animals survived and the unvaccinated ones did not, Hensley said.
“The vaccine was really successful,” said Webby, whose lab did this work last year in collaboration with Hensley.
The cow study will be similar to the initial test initially carried out on smaller animals. The plan is that initially around 10 calves will be vaccinated, half with one dose and half with another. Your blood will then be drawn and tested to see how much bird flu-fighting antibodies have been produced.
The USDA study will first have to determine the right dose for such a large animal, Hensley said, before testing whether it protects them as it did for smaller animals.
What “scares me most is the amount of interaction between livestock and humans,” Hensley said.
“We’re not talking about an animal that lives on top of a mountain,” he said. “If this were a bobcat outbreak, I would feel bad for the bobcats, but that’s not a huge human risk.”
If a vaccine reduces the amount of virus in the cow, “then ultimately we reduce the chance of a mutant virus emerging that spreads to humans,” he said.
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