By Dr. Horrys Friaça, Agricultural Health and Food Safety Specialist, IICA, horrys.friaca@iica.int
By Dr. Horrys Friaça, Agricultural Health and Food Safety Specialist, IICA, horrys.friaca@iica.int
Since it was first identified in the United States in December 2014 in the Pacific Northwest, highly pathogenic avian influenza (HPAI) has been detected in commercial and backyard poultry flocks, wild birds, or captive wild birds in 21 States. With the last case of the spring outbreak identified in June, 2015, a total of 211 commercial and 21 backyard poultry premises has been affected. This resulted in the depopulation of 7.5 million turkeys and 42.1 million egg-layer and pullet chickens, with devastating effects on these businesses, and a cost to Federal taxpayers of over $950 million.
To prepare for additional outbreaks that could occur in 2016 or later, the United States Department of Agriculture (USDA) planning activities assumed a worst-case scenario beginning in September 2015, with HPAI occurring simultaneously in multiple sectors of the poultry industry throughout the nation. Under this scenario, 500 or more commercial establishments of various sizes across a large geographical area could be affected. USDA’s plan for preventing and responding to future HPAI cases, in collaboration with industry and State partners, includes:
I. Preventing or Reducing Future Outbreaks
II. Enhanced Preparedness
III. Improved and Streamlined Response Capabilities
IV. Preparing for the Potential Use of AI Vaccines
Of all the aspects of the response to HPAI, vaccination is likely the most complex. The United States did not have a stockpile of AI vaccine at the start of the current detections; inventories of AI vaccine are fairly limited because poultry are not routinely vaccinated for HPAI in the United States. Last year, the USDA issued a determination that it would not be incorporating vaccination into HPAI response activities at that time, citing the lack of an AI vaccine that is well matched to the current outbreak virus and the possible negative impact on international trade.
USDA also indicated that it would reassess the vaccine question following further development of more effective vaccines.
To encourage private sector manufacturers to develop AI vaccines that could be ready this fall or winter, the USDA’s Animal and Plant Health Inspection Service (APHIS) has published two requests for proposals (RFP) on August 17 and November 20, 2015. The RFP enables the USDA to purchase vaccines to use in response to the outbreak or stockpile for future needs—either option will provide financial incentive for manufacturers. Researchers and vaccine companies are developing vaccines that use the genetics from the current HPAI virus that caused disease in spring 2015. They are studying how much protection the vaccine will provide for immunized birds. For those under development, the USDA is working closely with the manufacturers to expedite the review and approval of their products to ensure that they are available for use as quickly as possible. USDA regularly reviews new vaccine options as they are developed and submitted for licensing.
USDA has not approved the use of vaccine at this time. Before doing so, USDA would take into consideration the:
- extent and rate of spread of the outbreak (including the effectiveness of response activities),
- type of poultry operations affected,
- potential impact on domestic and international supplies and markets,
- potential impact on the ability of our American producers to export poultry overseas, and
- effectiveness and availability of vaccine
If APHIS approves vaccine use, it would not be used alone. Instead, it would be part of a larger, overall strategy to contain and eliminate the HPAI virus from the United States. While vaccinating, APHIS still would focus on enhanced biosecurity and surveillance, rapid depopulation, and other virus elimination methods to help end the outbreak. Ultimately, only these actions can achieve total eradication and restore the poultry industry to full production and exports
It is important to understand what HPAI vaccine would and would not do. HPAI vaccines reduce sickness, clinical signs, and death in domestic poultry. They would not prevent birds from becoming infected with the AI virus or from producing and shedding virus into the environment. That risk is apt to scare away potential buyers of vaccinated birds or products made from them. Vaccine would, however, reduce the amount of virus an infected bird sheds into the environment, which in turn helps prevent spread to new locations.
Acknowledging this reality, the USDA said, “During this outbreak, USDA has preserved open markets to countries that account for approximately 84 percent of the value of U.S. poultry and poultry products (including eggs) in 2014. However, some significant trading partners have indicated that, if we began vaccinating, they would ban all U.S. exports of poultry and eggs until they could complete a risk assessment.” Such risk assessments take time, and the loss of the markets could cost US poultry producers billions in lost export sales, with no clear timeline for reopening the markets, the agency said.
USDA would carefully target where to use vaccines; they would not be used on a widespread basis. Limiting vaccination to some areas and some species would offer the best chance of limiting crippling export sanctions. Producers would not be able to obtain vaccine from their veterinarian and proactively vaccinate their birds. Only USDA and State veterinarians would authorize vaccine use and monitor its administration.
After Vaccination Producers would not be allowed to move vaccinated birds outside of the vaccination area, unless the shipment was sent directly to slaughter under a permit from State or Federal animal health officials. Products from vaccinated birds could only be moved and used within the United States.
Animal health officials would regularly monitor and test vaccinated flocks for HPAI infection. If they find infection, APHIS would depopulate the flock and provide indemnity to the producer. APHIS would also work with producers to closely track all vaccinated birds through their normal lifespans to confirm when they are removed from the U.S. poultry population.
If there are indications that the vaccine strategy is not working to help contain the disease, APHIS would re-evaluate the use of vaccine. Finally, APHIS would stop vaccination after the outbreak is contained and HPAI eradicated. Once all vaccinated birds were removed from the U.S. poultry population, APHIS could re-declare the United States HPAI-free without vaccination.
Vaccination use was already mentioned in previous USDA strategies for HPAI outbreaks control, but due to the current preparedness level towards this possibility, it seems that the USDA would be more willing to actually incorporate vaccination use in its arsenal against HPAI, if it is needed. On the other hand, the U.S. recently approved animal health import requirements for beef from foot and mouth disease free areas, where vaccination is applied. A long standing paradigm over the lack of safety of free zones established with vaccination was then overcome.
As for other diseases, the World Animal Heath Organization (OIE) standards for HPAI surveillance and control also incorporate vaccination strategies and guidelines for the trade of vaccinated poultry and related products. The use of OIE standards to assure safety on animal products trade must be promoted as a way to reduce unfair and disproportionate practices in international trade. That can benefit all the countries in terms of access to healthy products, foreign consumer markets, wealth and increased animal welfare.
*The opinions expressed in this newsletter are those of the authors and they do not reflect the position of the Institute on the topics presented.
This post appears in the IICA Delegation in the USA Newsletter – January – February 2016
