Flu expert warns against USDA move to build bird flu vaccine stockpile

Suresh Mittal

The USDA has been building a stockpile of avian influenza vaccines to prepare for a potential outbreak, choosing Ceva Animal Health and recent Merck ($MRK) buy Harrisvaccines to manufacture the doses. But not everyone is on board with this idea, and one expert is cautioning against the USDA's move, saying that a quickly mutating virus could lead to a stockpile of useless vaccines.

Wild birds typically introduce the virus to backyard and commercial poultry flocks, so it's difficult to know the particular strain or nature of the virus until after outbreaks occur, said Suresh Mittal, a professor of comparative pathobiology in Purdue University's College of Veterinary Medicine, in a statement. "There is much to consider" before building a stockpile, Mittal said, including whether a vaccine can protect against a wide range of mutations.

Mittal and his research team studied the 2010 bird flu outbreak in vaccinated chickens at a poultry farm in Egypt and found that a vaccine offering broad protection did not ward off the illness in birds. The team took 10 samples from different sheds with thousands of birds, isolated the virus and pinpointed genes. The results showed that all samples had the same virus, H5N1, but different mutations of this strain led to the birds getting sick.

U.S. Agriculture Secretary Tom Vilsack

"This case highlights how easily a vaccine thought to be effective can be rendered useless in the face of rapid mutations," Mittal said. "What works against the viruses infecting birds today may not work against the virus we face tomorrow, as it rapidly mutates to avoid attack from the immune system. Luck--or a vaccine effective against a broad range of strains--is needed for an emergency stockpile to work when an outbreak hits."

Meanwhile, the USDA is rolling out a plan in case avian influenza returns. So far in 2015, the H5N2 bird flu has resulted in 48 million bird deaths and $3 billion in lost revenue. The agency said in September that it would push for stronger biosecurity practices, better outbreak detection and more resources to prepare for a possible resurgence of bird flu. U.S. Secretary of Agriculture Tom Vilsack has also asked poultry producers to be vigilant about potential risks such as sharing farm equipment and allowing wild birds on their properties.

"We're obviously hoping for the best, but during the last several months, we have been focusing on planning for the worst," Vilsack said in September.

- read the statement