When H1N1 swine flu first hit Hong Kong, the memories of SARS reverberated - a new infectious disease had emerged. Memories of the empty streets and restaurants, and fear in the community were undoubtedly factors which contributed to the positive endorsement of the government's draconian measures to contain the disease.

When an overwhelming majority (92 percent) of the public supported the quarantining of the guests at the Metropark hotel - where the only exposure to the disease was that of a Mexican guest who flew in with the disease - many other countries such as the US and UK were bemused.

Very early in the pandemic, the US stopped collecting statistics - recognizing both the mild nature of the disease and the community spread which had already occurred by this time. Over the next month the containment policy, which relied on social isolation and attempts to stop the spread in the community, was translated into a policy of mitigation - reducing the harm from the disease and minimizing its disruptive impact. The public recognized this was not the same as SARS and anxiety levels were significantly lower.

In countries such as Australia, US and UK, H1N1 was spreading through communities and since this is a disease which tends to affect younger people, it was not surprising it should be transmitted to Hong Kong by students returning from their studies abroad for their summer vacations and travelers on their holidays.

As the numbers of confirmed cases grew, the policies for how it should be treated were modified. It was no longer deemed necessary to quarantine, or to hospitalize, or even to receive Tamiflu for prophylaxis. International experts realized the disease would be around for some time to come - and in Hong Kong, we adapted our response to accommodate H1N1 as we accommodate seasonal flu.

Thus, when schools are faced with cases of flu, they no longer close unless criteria such as an infection rate of 10 percent are met - and even then they may close only affected classes rather than whole institutions.

The risks of infection are balanced against the benefits of staying in school - which are not only the benefits of less disruption to learning but also to family life since school suspension requires alternative domestic arrangements to be made and can be very difficult particularly for lower paid working mothers.

This leaves us facing a highly infectious disease that spreads rapidly but is in general a mild illness. Obviously, we worry about potential mutation of the virus and also the impact on high-risk groups such as those who are immunocompromised, those with chronic illnesses who are often elderly and also pregnant mothers. For them, there is the possibility of vaccination in the not too distant future as the vaccine becomes available in the Chinese mainland.

Other worries include a growth in Tamiflu resistance as well as the potential strain on health services. Two thirds of healthcare workers in Hong Kong say they do not wish to have the vaccine even if available - which, if large numbers were to become infected, could limit the ability of the healthcare system to respond effectively to increasing levels of disease.

Thus, it is important to continually reinforce the need for personal hygiene and responsibility if infected to minimize the potential harm of spread of the disease. The Centre for Health Protection website remains the best source of knowledge for such advice (www.chp.gov.hk).

The author is director of School of Public Health and Primary Care at the Chinese University of Hong Kong

(HK Edition 09/18/2009 page1)