(AP) -- Humans may not be the only ones guarding against swine flu by the time cold weather ushers in influenza season. The flu namesakes could also be getting new vaccinations.
The U.S. Department of Agriculture has given several animal vaccine manufacturers the "master seed virus" from the swine flu strain now circulating among humans. At least one of the companies said Wednesday it's developing a vaccination for pigs, which can contract the virus from infected people - in much the same way people do.
Flu viruses pass from human to hog mostly from coughing and sneezing, according to the Centers for Disease Control and Prevention.
A pig vaccine would help livestock producers prevent their animals from getting the novel H1N1 strain commonly called swine flu, as well as help thwart the development of other flu strains that could endanger humans and animals in the future.
Pigs, which also are susceptible to avian and human flu strains, are considered mixing vessels where the viruses can mutate together into novel variations.
"Through that mutation they can become more virulent and could cause problems in humans," said Dr. John Clifford, chief veterinarian for the USDA's animal-health division. "Also, for pigs themselves, if the virus changes, current vaccinations may not work."
So far, the swine flu causing global health concerns has not turned up in U.S. pig herds. But it has been found in herds in Canada, Argentina and Australia. Canadian officials announced the first documented case of the human H1N1 virus jumping from a person to pigs on a farm in May.
While enormous demand is expected when the human swine flu vaccination is released this fall, the jury's still out on how much demand there will be for a pig vaccine. Clifford said the USDA, which is responsible for approving any swine flu vaccinations for pigs, will not require hog farmers to vaccinate against the human strain.
Instead, officials will encourage hog farmers to vaccinate their animals in response to any swine flu outbreaks in U.S. pig herds.
A soft hog market, however, has many farmers pinching pennies, so it could take severe outbreaks, or ones close to home, to persuade them to spend money on a new vaccine.
Hog farmer Jerry Brink, of Elkader, Iowa, said he won't buy the vaccine unless there's an outbreak in the area surrounding his farm.
"The common thinking is, don't vaccinate if you don't have to," Brink said.
Hog farmers also are accustomed to their animals getting the flu - and then getting over it fairly quickly with minimal damage, said Dan Warner of the National Pork Producers Council.
"Pigs get the flu, it's a regular thing and they get over it and they're fine," Warner said. The vaccine being developed, he said, "would just be an added expense they couldn't afford."
Vaccines for various strains of swine flu that haven't hit the human population and are administered only to pigs already are on the market.
Clifford declined to identify which veterinary medicine manufacturers were working on the new vaccine to combat the strain currently found in humans, but Pfizer on Wednesday confirmed it was doing so at it's Lincoln, Neb., plant.
A spokeswoman for Swiss drugmaker Novartis said she could not confirm whether that company was working on the vaccine. Messages left with Boehringer Ingelheim Vetmedica Inc., of St. Joseph, Mo., and Fort Dodge Animal Health of Iowa were not immediately returned.
Pfizer officials said the vaccine could go on the market by the normal start of flu season, but demand would be significantly dampened without a requirement pigs be vaccinated. Michael Huether, a manufacturing director at the plant, said USDA officials indicated earlier this summer that the agency determine whether there would be a vaccination requirement "at a later date."
"We wouldn't require it," Clifford said Wednesday. "If we start seeing a lot of cases in swine, we'd certainly encourage swine producers to use it."
On the Net:
National Pork Producers Council: http://www.nppc.org/
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