Replies to LegCo questions

LCQ1: Preventive and control measures on seasonal influenza and avian influenza

Following is a question by the Hon Audrey Eu and an oral reply by the Secretary for Food and Health, Dr York Chow, in the Legislative Council today (February 11):

Question:

A number of confirmed cases of human infection of avian influenza have occurred on the Mainland since January this year, resulting in five deaths. At the same time, the World Health Organisation (WHO) has indicated that there is an increasing likelihood of a major global outbreak of influenza on a scale similar to that in 1968. In this connection, will the Government inform this Council:

(a) of the latest information about the avian influenza epidemic on the Mainland that the Government has obtained through the exchange and notification mechanism on infectious diseases; and

(b) in the face of the recent spate of fatal avian influenza cases on the Mainland and WHO's warning, what measures the Government will take to prevent the outbreak of influenza and human infection of avian influenza in Hong Kong?

Reply:

President,

Hon Eu's question touches on seasonal influenza and avian influenza. First of all, I would like to explain the differences between the two.

Seasonal influenza is caused by different strains of influenza virus transmitted among people. There are three known categories of influenza: A, B and C. The most common types of influenza in Hong Kong are influenza A H1N1 and H3N2. Minor changes of the antigen of influenza viruses every year lead to seasonal influenza. As such, reformulation of the influenza vaccine is required every year to cope with the mutation of viral strains. Influenza is mainly transmitted through air or droplet in crowded and enclosed areas, or through direct contact with the secretions of a person suffering from the disease.

As for avian influenza, it is usually caused by influenza A H5N1 and H9N2. While avian influenza normally infects birds, poultry are especially vulnerable to infections resulting in epidemics. According to the World Health Organisation (WHO), there have been over 400 human cases of avian influenza H5N1 globally since 2003, with the fatality rate of about 60%. Cases of human infection of avian influenza are usually the result of close contact with live poultry and their droppings. Wild birds are not a major channel of spreading avian influenza to human. Up till now, there is no epidemiological evidence to show that avian influenza can be transmitted to humans through consumption of properly cooked poultry according to WHO. Neither is there any evidence of efficient human-to-human transmission of the virus. In the circumstances, our strategy to prevent avian influenza is primarily on prevention of poultry from avian influenza infection, and minimising contact between the members of the public and live poultry.

An influenza pandemic occurs when there is an extensive human-to-human transmission of a new influenza virus or an influenza virus which has not been around for a long time. An influenza pandemic takes large toll as the majority of the population lack immunity to the virus.

My replies to the two parts of the question are as follows :

(a) As at February 10, the Department of Health (DH) has received notifications from the Ministry of Health (MoH) concerning eight confirmed human cases of avian influenza A H5N1 so far this year. Of these cases, five were fatal. Investigations conducted by the Mainland health authorities reveal that seven cases had contact with diseased poultry or exposure history to live poultry market in the Mainland prior to the onset of symptoms. The Mainland Government has taken preventive and control measures accordingly, including placing the close contacts of patients under medical surveillance and carrying out epidemiological investigations. The MoH's investigation reveals that all eight cases are sporadic cases without epidemiological linkage and there are no obvious signs of human-to-human transmission of the virus at the moment. Details of the cases are at the Annex.

(b) To mitigate the effect of seasonal influenza, the Centre for Health Protection (CHP) has been closely monitoring the local influenza situation through different channels, including the sentinel surveillance in general out-patient clinics, private clinics, homes for the elderly, child care centres, etc.

We provide free influenza vaccination for some high-risk target groups under the "Government Influenza Vaccination Programme" every year. The "Influenza Vaccination Subsidy Scheme" was also launched in November last year to provide government subsidies to encourage young children to receive influenza vaccination at private clinics, so as to reduce their risk of hospitalisation due to influenza.

In addition, at end of last year, we have stepped up our preventive publicity and education efforts before the arrival of the winter influenza season. The CHP has set up a dedicated webpage in its website to publish the updated figures and information on the influenza daily situation for public reference. The CHP also disseminates relevant messages and guidelines to doctors, homes for the elderly, hostels for people with disabilities, schools, kindergartens and child care centres from time to time, so as to strengthen the surveillance, prevention and control of influenza. These measures have not only facilitated effective surveillance of influenza in Hong Kong, but also significantly heightened public alertness to influenza.

As for avian influenza, the Government has already put in place a series of measures to reduce the risk of virus transmission from poultry and birds to human. These measures include banning the keeping of backyard poultry, requiring the compliance with biosecurity measures in local farms, requiring vaccination for chickens in local farms and imported chickens, banning the keeping of live poultry overnight at retail level, as well as enhancing the testing of antibodies for chickens in local farms and imported chickens. Besides, we have also arranged influenza vaccination for poultry workers and cullers to reduce the chance of genetic reassortment between human and avian influenza viruses. We are also actively pursuing the development of a poultry slaughtering plant to achieve complete segregation of humans from live poultry.

In respect of surveillance, avian influenza H5, H7 and H9 are currently notifiable infectious diseases under the Prevention and Control of Disease Ordinance. In addition to statutory notifications, the CHP also maintains close monitoring of the avian influenza situation locally through various means including laboratories and hospitals.

On the other hand, DH has implemented temperature screening for in-bound travellers in all Immigration Control Points and will conduct further assessment on those with fever or illness. For any suspected avian influenza cases, rapid diagnosis using molecular methods will be conducted by DH. Once avian influenza cases are detected, the DH will conduct epidemiological investigations promptly and take necessary control measures including contact tracing, environmental investigation, finding the source of infection and prevention of the spread of diseases.

We have all along been maintaining close communication and co-operation with the Mainland and Macao health authorities to ensure expeditious and effective exchange of important information about infectious disease outbreaks and incidents of the three places. Contingency measures have been taken to reduce the chance of infectious disease outbreak. In addition, we have been maintaining close liaison with WHO and the health authorities of other regions to obtain the latest information on avian influenza cases. Regular exercises and drills are also conducted to test and enhance the emergency preparedness of government departments in case of public health emergencies. Besides, health authorities in Hong Kong, the Mainland and Macao organise joint exercises regularly to review the emergency response and notification mechanism of the three places in handling cross-boundary public health emergencies.

Despite the occasional cases of human infection of avian influenza in other countries and places, there is no evidence yet of efficient human-to-human transmission of the virus. We will continue to minimise the risk of avian influenza and influenza pandemics through the above measures.


Ends/Wednesday, February 11, 2009
Issued at HKT 12:56

NNNN

Annex to LCQ1