Poultry Vaccination - Photo Credit OIE
Last week, in The HPAI Poultry Vaccine Dilemma, I wrote at some length on the problems inherent in turning to a poultry vaccine to control the HPAI H5 viruses spreading across North America.
Last November we looked at an EID Journal dispatch - Subclinical Highly Pathogenic Avian Influenza Virus Infection among Vaccinated Chickens, China – which addressed many of these concerns, and what they called the `multiple disadvantages of HPAI mass vaccination’, including the creation of vaccine-escape flu variants
Although HPAI vaccines can often prevent serious illness in poultry flocks, they often fail to prevent viruses from spreading, and eventually evolving into new strains. As these new variants appear, the vaccines become even less effective – turning their use into a gigantic slippery slope.
One that China, Egypt, Vietnam, and Indonesia have been unable to get off, despite warnings from the OIE that poultry vaccines must be considered a `short-term solution’ and counties must have an `exit strategy’ (see Avian influenza and vaccination: what is the scientific recommendation?).
Although the USDA has steadfastly supported quarantine and culling as the preferred method of dealing with bird flu in the United States, nervous poultry producers are calling for a vaccine option.
17:08 27 April 2015 by Debora MacKenzie
Bird flu is rampaging across the Midwestern US this week. So far 8 million chickens and turkeys have been destroyed to stop the spread of H5N2, an offspring of Asia's H5N1 bird flu. Minnesota, the top US turkey producer, declared an agricultural emergency after announcing infected farms almost daily for two weeks. Iowa, the top egg producer, killed 3.8 million hens on one farm alone.
US agriculture officials hope the outbreaks will diminish as summer warmth and sunshine destroys flu viruses in the environment. But their bird flu problems may be only beginning. Wild ducks could infect the rest of the continent next autumn.
And while H5N2, unlike H5N1, seems to pose little threat to humans, the $45 billion US poultry industry is already suffering, as China, South Korea and Mexico ban US produce. Producers are calling for a poultry vaccine, and the US Department of Agriculture says it is developing one. But that might just make the problem worse by encouraging the spread of "silent" infections.