The Hong Kong government (HKG) has decided to recommend Re-5 H5N1 AI vaccine as an alternative to the existing Intervet Nobilis H5N2 AI vaccine.
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Post: Hong Kong
HKG Approves New AI Vaccine for Poultry
Agriculture in the News
Poultry and Products
The Hong Kong government (HKG) has decided to recommend Re-5 H5N1 AI vaccine as an
alternative to the existing Intervet Nobilis H5N2 AI vaccine for the mandatory vaccination
program in local poultry farms after a 12-month successful field trial in two farms. The HKG
introduced mandatory vaccination for poultry since 2003 as one of the precautionary
measures against avian influenza outbreaks. However, an ensuing AI case in a local farm in
2008 prompted the HKG to evaluate the efficacy of the existing vaccine and to identify other
possible options. Based on research results and a year’s field trial, the HKG concluded that Re-
5 vaccine is effective in lowering AI risk and recommended its use in chicken farms. The Hong
Kong government regards AI risk level in Hong Kong, especially human infection, to be
relatively low and stable, although it also understanding that it is unrealistic to expect the
complete elimination of AI risk in the territory.
The first avian influenza outbreak in Hong Kong occurred in 1997 and the H5N1 virus killed six
people. Over the years, the HKG introduced a series of measures to combat AI risks. Since
then there was no local human infection other than two human imported cases in 2003, one in
2010, and one so far in 2012. There was no AI outbreak in local chicken farms since 2008.
However, there was one chicken carcass found infected with H5N1 in a wholesale market in
2011. The Hong Kong government concluded that the AI risk in Hong Kong remains low and
stable but it is not scientifically justifiable to expect complete elimination of AI risk.
The Hong Kong government developed and adopted a series of precautionary measures in the
past decade which have been proved effective in lowering AI risks in Hong Kong. These
1) Surveillance of birds at all levels such as poultry imports and local supplies;
2) Mandatory vaccination for both local and imported live chickens;
3) Enforcing biosecurity measures in local farms;
4) Restricting chicken imports from China to registered farms;
5) Prohibiting overnight stocking of live chickens in retail outlets;
6) Prohibiting backyard poultry;
7) Reducing the number of chicken farms through a “license surrender” program. The
current farm number stood at 30 with a total of 1.3 million chicken populations; and
8) Reducing the daily supply of live chickens to 15,000 head compared to 100,000 in 2003.
Between 1997 and early 2002, three major AI outbreaks occurred in Hong Kong. The first bird
flu crisis occurring in 1997 resulting in six confirmed human deaths. The other two outbreaks
happened in May 2001 and February 2002. The three major outbreaks led to the slaughter of
over 3 million chickens at a compensation cost of HK$200 million (US$26 million) paid to the
local industry by the government.
Subsequent to the outbreak in February 2002, the HKG introduced a vaccination program on a
trial basis in April 2002 in a farming district. The vaccine used was the Dutch Intervet Nobilis
H5N2, which was manufactured in Mexico. Vaccination was then extended to more farms
when Hong Kong suffered from another bird outbreak in December 2002. After one year of
trial with satisfactory results, the HKG decided to launch a mandatory vaccination program for
all local chicken farms starting in April 2003. In the following year, all chicken supplies from
China have to be vaccinated before being exported to Hong Kong. Thereafter, there was no
outbreak of AI in local chicken farms until December 2008.
The December 2008 AI outbreak was a concern because the death of 200 H5-infected chickens
included vaccinated as well as unvaccinated birds. The outbreak led to doubts about the
effectiveness of the vaccine in use. Local scientists warned that given the inherent property of
virus mutation, the diminishing effectiveness of the vaccines was inevitable, as these vaccines
have been on the market for more than 10 years ever since compulsory vaccination in 2003.
Following the outbreak of the AI in 2008, the HKG set up an investigation group to research on
the efficacy of Intervet vaccine and identify vaccine alternatives. The government then
commissioned three research institutions to conduct the study. The three vaccines studied
were the Intervet vaccine which has been in use since 2003, the Harbin Re-5 H5N1 vaccine in
use on chickens in China for exports to Hong Kong since 2008 and a H5N3 vaccine used in the
European Union since 2006.
The result of the studies showed that the Intervet vaccine was still effective against H5N1
virus, whereas Re-5 vaccine provided similar or even better protection as compared with the
Intervet vaccine. The HKG then launched a 12-month field trial for Re-5 in two local farms to
fully evaluate the efficacy of the vaccine. The field trial result indicated that the vaccinated
chickens had not responded adversely to the Re-5 vaccine. The Intervet vaccine and the Re-5
vaccine had comparable efficacy. Tests for the H5 viruses in both environmental samples and
swabs collected from chickens had been conducted and had yielded negative results.
Upon satisfactory field trial of Re-5 vaccine, the Hong Kong government decided to introduce
Re-5, in parallel to Intervet, as an alternative vaccine option for mandatory vaccination
program in Hong Kong.
Re-5 is yet to be registered for importation to Hong Kong. Reportedly, the HKG will allow the
use of Intervet and Re-5 in the same farm but each chicken batch has to stick to either one
vaccine in order to facilitate surveillance.
Farmers have mixed feelings over the new vaccine. They generally lack some confidence in the
efficacy of Re-5 vaccine as it has never been used in Hong Kong. However, the cost is expected
to be lower than Intervet. The price will be available after the vaccine has been registered and
made available in the market. Currently, the Dutch vaccine cost about HK$0.40 per injection.
Some farmers will probably switch to Re-5 on cost considerations.
The HKG indicated that a new vaccine, Re-6, would be introduced in due course in China to
match the prevailing clade 184.108.40.206 of AI virus commonly found in the region. They will closely
monitor the situation so as to evaluate its timely introduction to Hong Kong considering the
circulating strain of AI virus in Hong Kong.