Twenty-nine distinct epizootics of high-pathogenicity avian influenza (HPAI) have occurred since 1959. The H5N1 HPAI panzootic affecting Asia, Africa and Eastern Europe has been the largest among these, affecting poultry and/or wild birds in 63 countries. A stamping-out programme achieved eradication in 24 of these epizootics (and is close to achieving eradication in the current H5N2 epizootic in South African ostriches), but vaccination was added to the control programmes in four epizootics when stamping out alone was not effective. During the 2002 to 2010 period, more than 113 billion doses of avian influenza (AI) vaccine were used in at-risk national poultry populations of over 131 billion birds. At two to three doses per bird for the 15 vaccinating countries, the average national vaccination coverage rate was 41.9% and the global AI vaccine coverage rate was 10.9% for all poultry. The highest national coverage rate was nearly 100% for poultry in Hong Kong and the lowest national coverage was less than 0.01% for poultry in Israel and The Netherlands. Inactivated AI vaccines accounted for 95.5% and live recombinant virus vaccines for 4.5% of the vaccines used. Most of these vaccines were used in the H5N1 HPAI panzootic, with more than 99% employed in the People's Republic of China, Egypt, Indonesia and Vietnam. Implementation of vaccination in these four countries occurred after H5N1 HPAI became enzootic in domestic poultry and vaccination did not result in the enzootic infections. Vaccine usage prevented clinical disease and mortality in chickens, and maintained rural livelihoods and food security during HPAI outbreaks.（雞隻疫苗使用在高致病性禽流感爆發期間防止臨床疾病和死亡，和維持農村生計和糧食安全。） Low-pathogenicity notifiable avian influenza (LPNAI) became reportable to the World Organisation for Animal Health in 2006 because some H5 and H7 low-pathogenicity avian influenza (LPAI) viruses have the potential to mutate to HPAI viruses. （低致病的流感變成必須報告的，因為部分H5 H7的低致病病毒是會導致高致病性突變的）Fewer outbreaks of LPNAI have been reported than of HPAI and only six countries used vaccine in control programmes（）, accounting for 8.1% of the total H5/H7 AI vaccine usage, as compared to 91.9% of the vaccine used against HPAI. Of the six countries that have used vaccine to control LPNAI, Mexico, Guatemala, El Salvador and Italy have been the biggest users. In countries with enzootic HPAI and LPNAI, development and implementation of exit strategies has been difficult.

The H5N1 highly pathogenic (HP) avian influenza (AI) epizootic began with reports of mortality from China in 1996 and, by June 2005, caused outbreaks of disease in nine additional Asian countries, affecting or resulting in culling of over 200 million birds. Vaccines can be used in programs to prevent, manage, or eradicate AI. However, vaccines should only be used as part of a comprehensive control strategy that also includes biosecurity, quarantine, surveillance and diagnostics, education, and elimination of infected poultry.（疫苗只應被用來作為一個全面的控制策略的一部分，其中還包括生物安全，檢疫，監測和診斷，教育，撲殺受感染的家禽。） Potent AI vaccines, when properly used, can prevent disease and death, increase resistance to infection, reduce field virus replication and shedding, and reduce virus transmission, but do not provide "sterilizing immunity" in the field; i.e., vaccination does not completely prevent AI virus replication. Inactivated AI vaccines and a recombinant fowlpox-H5-AI vaccine are licensed and used in various countries. Vaccines have been shown to protect chickens, geese, and ducks from H5 HPAI. The inactivated vaccines prevented disease and mortality in chickens and geese, and reduced the ability of the field virus to replicate in gastrointestinal and respiratory tracts. 疫苗證明可以在H5高致病性禽流感威脅下保護雞，鵝，鴨。滅活疫苗在雞，鵝，降低病毒複製，防止疾病和死亡，胃腸道和呼吸道的能力降低。Although the Asian H5N1 HPAI virus did not cause disease or mortality in ducks, the use of inactivated vaccine did reduce field virus replication in the respiratory and intestinal tracts. The inactivated vaccine protected geese from morbidity and mortality, and reduced challenge virus replication. 使用滅活疫苗的減少現場呼吸道和腸道病毒複製。滅活疫苗保護鵝發病率和死亡率，並減少攻擊病毒複製。The recombinant fowlpox-H5-AI vaccine has provided similar protection, but the vaccine is used only in chickens and with the advantage of application at 1 day of age in the hatchery.

Vaccination of chickens with a commercially available killed H5N2 vaccine was being evaluated as an additional tool to enhanced biosecurity measures and intensive surveillance for control of highly pathogenic avian influenza subtype H5N1 disease in Hong Kong in 2002. In December 2002 to January 2003, there were outbreaks of H5N1 disease in waterfowl in two recreational parks, wild water birds, several poultry markets and five chicken farms. In addition to quarantine, depopulation of the affected sheds and increased biosecurity, vaccination of the unaffected sheds and surrounding unvaccinated farms was undertaken on three farms. In at least two farms, infection spread to the recently vaccinated sheds with low rates of H5N1 mortality in sheds when the chickens were between 9 and 18 days post-vaccination. However, after 18 days post-vaccination no more deaths from H5N1 avian influenza occurred and intensive monitoring by virus culture on these farms showed no evidence of asymptomatic shedding of the virus. This provides evidence that H5 vaccine can interrupt virus transmission in a field setting.

18天接種後，沒有發生更多死於H5N1禽流感的例子，用病毒培養的密切監測這些農場，沒有證據顯示無病毒症狀下的排毒。這證明H5疫苗可以在現場設置中斷病毒的傳播。

Copyright 2004 Houghton Trust Ltd

Efficacy of inactivated H5N2 influenza vaccines against lethal A/Chicken/Queretaro/19/95 infection.

Outbreaks of H5N1 highly pathogenic avian influenza (HPAI) that occurred in Hong Kong up until February/March 2002 were controlled by stamping out. With endemic presence of the virus in the region and large daily importation of poultry to Hong Kong, the Administration considered that further risk management measures, in addition to improved biosecurity and enhanced surveillance, were necessary to prevent outbreaks. Vaccination using a killed H5N2 vaccine was evaluated over a 12-month period in the district with the last HPAI cases in the early 2002 outbreak. The vaccination trial showed that farmer-administered killed H5N2 vaccine produced suitable flock antibody responses; vaccinated birds were protected against H5N1 HPAI virus challenge and excreted significantly less H5N1 virus; and vaccination was able to control virus excretion in flocks during field outbreaks. Universal vaccination of local chicken farms was introduced in June 2003 and by the end of 2003 all chickens entering the live poultry markets in Hong Kong were vaccinated by killed H5N2 vaccine. In addition to vaccination, an enhanced biosecurity programme on farms and in live poultry markets and a comprehensive surveillance programme in poultry, wild birds, recreation park birds and pet birds were in place. Vaccination use and performance is closely monitored. This programme was successful in protecting local farms and live poultry markets from H5N1 outbreaks during the regional H5N1 outbreaks in 2004.

在2003年6月和2003年年底本地雞場引入普遍接種，在香港的活家禽市場所有雞隻接種殺死後的H5N2疫苗。除了接種疫苗，也在農場和活禽市場加強生物安全程序，和在家禽、野生鳥類、休閒公園鳥、和觀賞鳥執行全面的監察計劃。密切監測接種疫苗的使用和性能。在2004年爆發的H5N1禽流感爆發期間這個計劃成功地保護當地養殖場和活禽市場。