Hong Kong recorded 770 severe influenza cases by October 7, including 629 among people aged 65 and over. Of those older patients, 487 had died, according to Centre for Health Protection figures reported by local media.
A professor in the Department of Medicine at The University of Hong Kong said older people and those with chronic conditions such as cardiovascular disease, diabetes or cancer face greater risks of complications. Existing illnesses can worsen rapidly after influenza infection, he said.
For people with cardiovascular disease, studies he cited found that the risk of an acute heart attack rose six to 17 times in the week after an influenza diagnosis. The risk of stroke rose about eight to 10 times.
The president of The Society of Hospital Pharmacists of Hong Kong described three main trivalent vaccines used in the city: injectable inactivated, nasal live-attenuated and injectable recombinant. Their safety is similar, he said, but the nasal vaccine is unsuitable for older people.
He recommends prioritising recombinant vaccine for people aged 65 and over. It contains three times the antigen quantity of inactivated vaccine and, he said, can produce higher antibody levels and protection in older people. He also said it is suitable for people with severe egg allergies.
Vaccine components change as circulating strains change, so older people should be vaccinated every year, the association president said. Older people choosing a vaccine can consult a doctor, pharmacist or healthcare staff at a district health centre.