True scale of flu deaths dwarfs reported cases
Study finds the virus kills 250 times more often than thought
Deaths from influenza are under-reported by about 250 times, University of Hong Kong scientists said yesterday.
They said the deaths could be avoided with better information about the dangers and the vaccination of more people at high risk.
The university's team of epidemiologists and virologists said there were more than 1,000 flu-related deaths each year, but just four were reported in 2000. The team estimated that 933 people aged 65 and over and 140 people under 65 died from flu each year.
Of the 1,073 deaths, 813 people died of pneumonia, pulmonary disease and heart attacks brought on by flu, the HKU researchers said.
The study, published in the December issue of Clinical Infectious Diseases scientific journal, is the first research to analyse flu patterns in a tropical area.
'Because of the lack of well-defined seasonal patterns in tropical areas, influenza may not be recognised in reported causes of death,' said Wong Chit-ming, associate professor of the university's department of community medicine.
All previous studies were done in temperate regions such as the US, Britain and Europe, where one peak season in winter makes flu-related deaths easy to identify.
The findings supported the observation that flu peaks twice in the year - in the spring and summer - in Hong Kong, said Anthony Hedley, chair professor of the department of community medicine.
Malik Peiris, head of the virus unit of the department of microbiology, said the findings showed that people over 65, children aged six to 23 months and the chronically ill should be vaccinated against the flu to mitigate deaths and complications.
'In the last few months there have been very few influenza viruses circulating in Hong Kong. However, just in the last week, we have begun to see a slight increase in flu-virus activity. It is very likely that this activity will likely continue to increase on the basis of past experience,' Professor Peiris said.
The doctors also said that sick people should wear face masks to avoid spreading the flu to others.
'Our view is that people should wear masks when they go to crowded places and certainly if they have symptoms,' Professor Hedley advised.
Flu patients continued being contagious for a week or maybe more, infecting other people when they sneeze or cough, he said.
The Department of Health had so far vaccinated 180,000 people, including elderly people in homes, institutionalised handicapped people, poultry workers and health workers out of a targeted 200,000 people, a spokesman said.