LCQ20: Prevent and control influenza outbreaks

     Following is a question by the Hon Frederick Fung and a written reply by the Secretary for Food and Health, Dr York Chow, in the Legislative Council today (December 14):


     It has been reported that the health authorities in the United States earlier expressed concern about a new H3N2 influenza (flu) virus mutated from H1N1 human swine flu virus, pointing that this flu variant, which combines the genes from the viruses of ordinary human flu, H5N1 avian flu and H1N1 human swine flu, can be transmitted among humans, and there is a possibility of a major outbreak.  In this connection, will the Government inform this Council:

(a) whether the authorities have approached the overseas health authorities concerned and the World Health Organisation to seek the latest information about the aforesaid new flu virus; if they have, of the details (including the characteristics of the aforesaid new flu virus, mode of transmission and spreading rate, symptoms as compared with those of ordinary flu, possible complications, methods of treatment, as well as comparison with the human swine flu epidemic which broke out and spread in Mexico in 2009, etc.); and

(b) of the mechanism currently in place for comprehensively monitoring the possible appearance of any new flu variant; whether the authorities have any measure (e.g. any plan to specify the aforesaid new flu as a statutory notifiable disease, etc.) in place at present to cope with the possible major outbreak of the aforesaid new flu; and whether they have formulated any contingency plan for the purposes of perfecting the mechanism for the prevention and control of flu, disseminating information, flexibly deploying and purchasing medical resources, organising and coordinating the work of various government departments in combating epidemics, strengthening public health education and immunisation, etc.; if they have, of the details?



     Following the establishment of the Centre for Health Protection (CHP) in 2004, the Government has established a comprehensive surveillance system that monitors influenza activity in the community.  The system includes laboratory surveillance and sentinel surveillance networks which cover childcare centres, kindergartens, residential care homes for the elderly, Hospital Authority out-patient clinics, clinics of private practitioners and Chinese medicine practitioners.  Moreover, the authorities have been working closely with local universities to gather expertise and experience from various specialties in order to formulate strategies and measures for the prevention and control of influenza.

     In monitoring the latest global situation of influenza, the Government has also been collaborating closely with health authorities such as the World Health Organisation (WHO), the Ministry of Health of China and the Centers for Disease Control and Prevention (CDC) of the United States (US).  In the regional context, the Government has established a direct communication mechanism with the relevant authorities of Guangdong Province and Macao.  This ensures that the three places can expeditiously and effectively exchange important information about influenza outbreaks, and contingency measures can be taken to reduce the chance of outbreaks.

     As far as seasonal influenza is concerned, it should be noted that serious influenza infections can occur even in healthy individuals, and that influenza vaccines are safe and effective.  Therefore, the authorities encourage all members of the public to consult their family doctors to receive seasonal influenza vaccination for personal protection.  On the other hand, the Scientific Committee on Vaccine Preventable Diseases under CHP will take into account a variety of scientific factors, including the local disease burden and international experience, before recommending priority target groups for seasonal influenza vaccination.  Priority target groups recommended for seasonal influenza vaccination in the 2011/12 season include children aged between 6 months and less than 6 years, persons aged 50 years or above, pregnant women, pig farmers and pig-slaughtering industry personnel etc.

     My reply to the two parts of the question is as follows:

(a) The Government has been closely monitoring developments concerning a swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus in the US.  CHP has written to WHO and CDC in order to understand and follow up on the latest developments concerning the virus in the US.

     According to information provided by WHO and CDC, there have been 11 recorded cases of the reassortant virus in the US since July this year.  All infected patients have recovered and the majority of cases involved relatively mild illness.  Seven of the cases (including two in Indiana, three in Pennsylvania and two in Maine) involved direct or indirect exposure to swine.  Epidemiological investigations conducted by the US authorities so far revealed that the four latest cases recently reported had no direct exposure to swine before the onset of symptoms - among the cases, three cases reported in Iowa involved children studying in the same childcare facility and investigation is underway to ascertain whether other children in the same childcare facility and their family members had exposure to swine; one other case was reported in West Virginia and further investigation of contacts and potential sources of infection are ongoing.  According to the epidemiological investigations on these four cases, limited human-to-human transmission may have occurred but there is no evidence of sustained human-to-human transmission of the virus.  According to advice of the CDC, the virus is susceptible to oseltamivir (Tamiflu) and zanamivir (Relenza).  As the virus is different to the influenza A (H3N2) virus common to humans, the existing seasonal influenza vaccine can only provide limited cross-protection against the virus to adults and cannot provide protection to children.

     Generally speaking, swine influenza, including the aforementioned swine influenza A (swine flu), is a respiratory disease of pigs caused by type A influenza virus.  Swine flu viruses commonly cause influenza outbreaks among pigs, and do not normally infect humans.  There have been sporadic human infections with swine flu and the majority of such cases involved direct exposure to swine.  Symptoms are similar to those of human seasonal influenza.

     Influenza A (H1N1) 2009, which broke out in Mexico and spread in 2009, was an exceptional case.  There was sustained human-to-human transmission and spread rapidly across the globe.  This is different to the swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) mentioned in the question.

     The Government will continue to closely monitor the situation and update the public on any new developments concerning the virus.  A relevant press release was issued on November 29, 2011.

(b) The Government has been closely monitoring influenza activity in the local community and has established a comprehensive disease surveillance system through collaboration with the Hospital Authority and private hospitals, general practitioners and institutions on sentinel surveillance; investigation of institutional outbreaks; hospital admissions data monitoring and media monitoring.  Results of influenza surveillance are uploaded weekly on the CHP website for public information.

     In addition, the Government has a sensitive laboratory surveillance system for influenza virus.  The Public Health Laboratory Services Branch under CHP conducts characterisation of all influenza viruses detected, including antigenic and genetic analysis.

     In 1999, the Department of Health recorded a case of a child infected with a swine-origin influenza A (H3N2) virus.  The child recovered and was discharged after two days of hospitalisation.  To date, no human infections with this swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus in the US have been detected in Hong Kong.

     The Centre for Food Safety has also been assisting the University of Hong Kong in conducting research and surveillance on influenza activity in pigs at the slaughterhouse.  Recent surveillance results revealed that a swine influenza H3N2 virus that had picked up genes of the influenza A (H1N1) 2009 virus, detected at the Sheung Shui Slaughterhouse, was different from the swine-origin triple reassortant influenza A (H3N2) (S-OtrH3N2) virus in the US.

     Under the Prevention and Control of Disease Ordinance (Cap. 599), at present type A influenza viruses (H2, H5, H7 and H9) are notifiable infectious diseases.  The Government will continue to closely monitor the development of influenza globally and locally, and strengthen its liaison with WHO, Mainland and overseas health authorities.  We will also pay particular attention to whether there is a genetic mutation of the virus and whether viral virulence and transmissibility have increased.  If necessary, we will make amendments to the legislation to include other viruses as statutorily notifiable diseases.

     In addition, the Government has adopted a multi-pronged approach to prevent and control influenza outbreaks.  We have formulated the Framework of Government's Preparedness Plan for Influenza Pandemic, which set outs in detail the command structure, preparation and control measures for influenza pandemic in Hong Kong.  The Plan includes a number of preventive and control measures in case of novel influenza and influenza pandemic, such as stepping up surveillance and rapid diagnosis, maintaining medical services, promoting basic protection measures like personal and environmental hygiene, risk communication etc.

     To ensure that relevant Government departments are well prepared for major infectious disease outbreaks, CHP regularly conducts exercises and drills on the preparedness plan, so as to test our preparedness and responsiveness for infectious disease outbreaks in Hong Kong.  The Government will also continue to maintain a stockpile of some 20 million doses of antivirals to meet the needs in case of an influenza pandemic.

Ends/Wednesday, December 14, 2011
Issued at HKT 12:30