LONDON (Reuters) - The death
rate from SARS could be as high as 55 percent in people over 60 years old
and 13 percent in those under 60, an international team of scientists estimated
Researchers and health officials in Hong Kong and Britain, who examined
data from the first nine weeks of the outbreak of the mysterious virus
in Hong Kong, also found the incubation period -- the time from infection
to displaying symptoms -- averaged six days.
"Our best estimate for the under 60s is between seven and 13 percent
and our best estimate for the over 60s is between 43 and 55 percent,"
Professor Christl Donnelly of Imperial College London, who worked on the
research, told Reuters.
"Although this study shows the fatality rate from SARS is higher than
previously thought, we now know that public health interventions have been
successfully reducing the spread of the disease," she added.
The study, published online by The Lancet medical journal, is the first
published epidemiological analysis of the spread of SARS.
The World Health Organisation (WHO) warned last week the SARS death rate
was likely to rise, but these latest estimates are much higher than the
previous 6-10 percent figures.
Donnelly said that in a growing epidemic, early death rates often underestimate
the true mortality rate.
"We have no evidence to show that the death rate has gone up over
time. Instead we've gained more information about it and this is using
the most statistical robust analysis technique to date," she explained.
SARS has killed hundreds of people and infected thousands since it broke
out in southern China last November.
The research also showed the time from onset of symptoms to admission to
hospital decreased from five to three days over the course of the outbreak.
"If it can be dropped further it will have an important
effect on reducing transmission," Donnelly said.
Estimated time from hospital admission to death from SARS was 36 days,
and from admission to discharge was 23.5 days.
Efforts by Hong Kong officials to quickly identify and confirm cases and
in quarantining, monitoring and encouraging people with symptoms to report
to hospital helped slow the outbreak, the scientists added.