USDA developing backup vaccine for two bird flu strains

Avian flu
Avian flu | Courtesy of extension.org

The U.S. Department of Agriculture is developing a vaccine to fight the highly pathogenic avian flu (HPAI) strains H5N2 and H5N8 currently threatening poultry flocks around the country.

The vaccine, which would be used to fight both viruses, is being developed as a backup tool in case standard containment measures fail, David E. Swayne, director of the USDA Agricultural Research Service’s Southeast Poultry Research Laboratory in Athens, Ga., told Vaccine News Daily.

“As researchers, we always … prepare for the worst possible option, which would be to use a vaccine,” said Swayne, whose lab is developing the vaccine. “Historically, we’ve never had to use a vaccine, but it’s important to have vaccines that we know could work.”

Avian influenza – known as AI or simply the bird flu – infects wild birds and domestic poultry. The HPAI strain is often fatal in chickens and turkeys and spreads rapidly, according to the USDA.

The new H5N2 virus is an offshoot of the H5N8 strain that originated in Asia. Since December 2014, the USDA has confirmed several cases of the virus in wild birds, as well as in some turkey and poultry flocks in Arkansas, California, Kansas, Minnesota, and Missouri. Evidence of the H5N2 virus also has been reported in Iowa and Wisconsin.

The good news is that the United States has the strongest AI surveillance program in the world, Swayne said. Not only are scientists at the SEPRL routinely evaluating existing bird flus in order to produce vaccines that fight new and emerging AI viruses, they also are working to develop vaccine seed strains to best protect poultry against AI.

The ongoing process to develop a vaccine occurs in stages, with the subsequent outcomes dictating the next steps for testing and further studies. So without a set time frame, Swayne said the SEPRL can’t predict when a vaccine has reached the stage where it may be used in poultry. And the lab provides information and data; it does not manufacture AI vaccines nor decide when or if vaccines should be used in the field. The licensing and use of a vaccine is determined by USDA’s Animal and Plant Health Inspection Service.

Using a vaccine, Swayne said, is important to have as part of the USDA’s existing AI rapid response plan.

Currently, he added, the lab has a vaccine construct that could make an injectable vaccine possible, “but it first would have to be tested and used in a study to determine if it would provide protection to poultry.”

The Centers for Disease Control and Prevention considers the risk to people from these HPAI H5 infections to be low and reports that no human cases of these viruses have been detected in the U.S., Canada, or internationally.