Health authorities are urging people to get vaccinated against flu ahead of winter after 2017's atypical season that saw a mild winter and bad summer peak.
Subsidized and free vaccination programs will be launched today and next Wednesday for flu and pneumococcal vaccination to eligible people, Centre for Health Protection controller Wong Ka-hing said yesterday.
Some 460,000 flu shots - subsidized at HK$190 per dose - have been ordered for high-risk people, including pregnant women, children aged six months to under 12, and people aged 50 or over.
Hong Kong saw an unusually severe summer peak that killed 431 people, including three children. The summer season also started earlier than usual - in mid-May - and lasted about 16 weeks.
By contrast, the winter flu season, which usually lasts longer and is more severe than the summer peak, was shorter at seven weeks from mid- February to early April compared to 17 weeks in 2015 and 2016, the CHP said.
The four-strain shot contains the Hong Kong H3N2-like virus, based on the World Health Organization recommendation in February for the Northern Hemisphere, where the SAR falls.
A WHO meeting in Melbourne late last month decided that for the Southern Hemisphere's 2018 flu season, the vaccine mix should do away with the Hong Kong strain.
"We don't know what would be the [dominant] strain this time yet so there is no such thing as vaccine mismatch," Wong said.
He said the H3N2 strain predominated in both 2017 winter and summer, accounting for 78 percent and 89 percent respectively of all positive detections.
"We can't predict how serious the winter flu outbreak will be, or the level of effectiveness of the vaccines for a particular strain," Wong said.
"But the public should get vaccinated as soon as possible for better protection."
The antigens of the Singapore-like H3N2 virus and the Hong Kong one were very similar.
"At this point, we don't see the grounds to import the new mix," Wong said. "There is not enough time to do so anyway, as the vaccine will not be available until March to April next year, by which time the winter flu peak would have passed."
The government will offer a stronger 13-valent pneumococcal conjugate vaccine for some 180,000 high- risk elderly persons for the first time. It has better efficacy against non-invasive pneumococcal pneumonia when compared with the 23vPPV vaccine.