H7N9, the bird flu strain that has health officials on edge, is now on Hong Kong's doorstep. A confirmed case in the Guangdong city of Huizhou, just 95 kilometres away, brings the inevitability of infections nearer. Precautionary checks of wet markets and people and poultry crossing from the mainland have been in place since March. Our government is doing its part to stave off the spread of a worrisome virus, but we also have an important role to play by using common sense and being vigilant.
Of the 134 people so far stricken, 45 have died. That is a fatality rate half a dozen times more than that for common seasonal flu. H7N9 has caused more human infections in a shorter period than any other bird flu. It has undergone genetic changes that suggest it could evolve to become easily transmissible between humans. A pandemic would then loom.
Scientists believe it has already jumped between people. A woman and her father in Jiangsu both died from the virus; although the man had had contact with poultry, his daughter had not. But there is no need for alarm. Researchers have pointed out the virus has "not gained the ability for efficient sustained transmission from person to person".
We cannot be complacent, though. Flu viruses are constantly changing and health experts predict H7N9 could easily make the transition. Given Hong Kong's tourism and trade links to the mainland and Taiwan, the only places where H7N9 has been reported, we are vulnerable in the extreme.
A watchful eye has to be kept when travelling on the mainland and overseas. The little-understood Middle East Respiratory Syndrome, recently linked to camels, has killed 46 of the 94 people infected since September. Both it, and H7N9, prove viral outbreaks do not occur only in cooler weather.
Hong Kong is fortunate in that it has a wealth of experience with infectious diseases. In the past decade, it has had to deal with severe acute respiratory syndrome, the H5N1 strain of bird flu and H1N1 swine flu. Our scientists are world virus experts and our government is as prepared as can be. Co-operation with the mainland is sturdy.
H7N9 is a new virus in humans and much is still to be learned about how it is transmitted and spread. Until it is better understood, we can only rely on past experience with similar viruses. That means avoiding live poultry and wild birds and people with flu symptoms. Being vigilant is our best defence.