Flu pandemic impact can be mitigated in cities - study

A densely populated city like Hong Kong can cut by half the number of infections in the first year of a flu pandemic using home quarantine, hospital isolation and anti-virals, a study suggests.

Scientists from the University of Hong Kong assumed a fully fledged influenza pandemic in a city such as Hong Kong, which has a population of 6.8 million.

"We showed that with the combination of tried, tested public health interventions such as quarantine, isolation and anti-virals, you could conceivably reduce the symptomatic attack rate from 49 percent all the way down to 27 per cent," said Gabriel Leung, an associate professor at the university's School of Public Health.

Symptomatic attack rate is defined as the proportion of a population that is infected and showing symptoms.

Experts fear the H5N1 strain of bird flu, which made the first known jump to humans in Hong Kong in 1997, could mutate and become easily transmissible among people, triggering a pandemic that could kill millions of people.

Through home quarantine of suspected cases, hospital isolation of symptomatic cases and anti-viral therapy, Prof. Leung said infections in a population such as Hong Kong's could be cut by half. "That means about 16,000 fewer deaths if you assume a case fatality rate of about one per cent, if you assume the New York experience in (the Spanish flu of) 1918," Prof. Leung said.

The government would need to stockpile 3.9 anti-viral capsules (75 milligrams each) for each citizen, which in Hong Kong's case would amount to 27 million capsules.

The study paints scenarios of what could happen at the peak of a pandemic, which in Hong Kong's case could mean 500,000 people in home quarantine and up to 70,000 others needing isolation beds - a challenging prospect for any city government.

"During SARS (in Hong Kong), government people and police went to each quarantined household to deliver water, bread and so on, but this was because it was a very small number. But for 500,000 people, that would not be an option," Prof. Leung said.

"So should governments be thinking of neighbourhood depots with centralised supplies and people will come pick them up and you make sure that they wear proper precautions when they come out? We don't have all the answers but what we would like to do is to pose some questions," he said.