Title: Impact of vaccines and vaccination on global control of avian influenza Author
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 12, 2012
Publication Date: December 1, 2012
Citation: Swayne, D.E. 2012. Impact of vaccines and vaccination on global control of avian influenza. Avian Diseases. 56(4): 818-828. Interpretive Summary: Thirty major outbreaks of deadly bird flu or high pathogenicity avian influenza (HPAI) have occurred in birds in the world since 1959. H5N1 HPAI has affecting Asia, Africa and Eastern Europe, infecting poultry and/or wild birds in 63 countries making it the worst bird flu outbreak in over 50 years. Eradication programs using education, biosecurity, rapid diagnostics and surveillance, and elimination of infected poultry by depopulation has been used in poultry to control HPAI in most countries, but vaccination was added in 15 countries affected by H5N1 bird flu to assist in control. From 2002 to 2010 period, over 113 billion doses of H5 avian influenza (AI) vaccine were used in poultry at 2-3 doses per bird The highest coverage rate was near 100% for poultry in Hong Kong and lowest was <0.01% for poultry in 7 countries. Killed AI vaccines accounted for 95.5% and live vaccines for 4.5%. Over 99% of the vaccine was used in China, Hong Kong, Egypt, Indonesia and Vietnam. Vaccination began in these five countries/regions after H5N1 HPAI became established in domestic poultry. Vaccines prevented disease and death in chickens, and maintained rural livelihoods and food security.
Technical Abstract: There have been 30 epizootics of H5 or H7 high pathogenicity avian influenza (HPAI) from 1959 to early 2012. The largest of these epizootics, affecting more birds and countries than the other 29 epizootics combined, has been the H5N1 HPAI which began in Guangdong China in 1996, and has killed or resulted in culling of over 250 million poultry and/or wild birds in 63 countries. Most countries have used stamping-out programs in poultry to eradicate the H5N1 HPAI. However, 15 affected countries have utilized vaccination as a part of the control strategy. Greater than 113 billion doses were used from 2002-2010. Mongolia, Kazakhstan, France, The Netherlands, Cote d’Ivoire, Sudan, North Korea, Israel, Russia, and Pakistan used <1% of the AI vaccine, and the AI vaccine was targeted to either preventive or emergency vaccination programs. Five countries have utilized nationwide routine vaccination programs which accounts for 99% of vaccine used: 1) China (90.9%), 2) Egypt (4.6%), 3) Indonesia (2.3%), 4) Vietnam (1.4%), and 5) Hong Kong SAR (<0.01%). Inactivated AI vaccines have accounted for 95.5% and live recombinant virus vaccines for 4.5% of vaccine used. Six countries have enzootic H5N1 HPAI. China, Indonesia, Egypt and Indonesia implemented vaccination after H5N1 HPAI became enzootic in domestic poultry. Bangladesh and eastern India have enzootic H5N1 HPAI and have not used vaccination in their control programs. Clinical disease and mortality were prevented in chickens, human cases have been reduced, and rural livelihoods and food security were maintained by using vaccines during HPAI outbreaks. However, field outbreaks have occurred in vaccinating countries primarily because of inadequate coverage in the target species, but vaccine failures have occurred following antigenic drift in field viruses within China, Egypt, Indonesia, Hong Kong and Vietnam. The primary strategy for HPAI and H5/H7 LPNAI control will continue to be immediate eradication by a four component strategy: 1) education, 2) biosecurity, 3) rapid diagnostics and surveillance, and 4) elimination of infected poultry. Vaccination can be a second tier component or ‘tool’ when immediate eradication is not feasible, to maintain livelihoods and food security, and to control clinical disease until a primary strategy can be developed and implemented to achieve eradication.