Nanjing, a former Chinese capital, had so far reported only four Sars cases and no deaths, prompting speculation that official figures may still not give a true picture, despite government assurances.

The mass quarantining yesterday is the most severe one-off response to Sars in China so far and could be followed by action to quarantine several hundred thousand people or to restrict the public’s freedom to move in cities where new outbreaks are feared.

The news from Nanjing is a blow to the Government, which had repeatedly congratulated itself on keeping Shanghai, Nanjing’s neighbour, Sars-free. If the virus is now rampant on the outskirts of China’s commercial centre, the long-feared economic impact may be about to hit.

The Government had been especially keen to isolate Shanghai because it is home to the country’s most important investors, who make up the financial backbone of China’s previously booming economy.

Sars first appeared in November in southern Guangdong province and spread locally early this year. In March, the outbreak reached Beijing and the surrounding northern Chinese provinces, having apparently bypassed the highly industrialised eastern seaboard and central Yangtse river delta.

The quarantining of 10,000 people in Nanjing is a desperate attempt to stem the outbreak before it reaches the city limits of Shanghai, which has reported only a few cases. The move increases the number of people in quarantine, which is said to be somewhere between 20,000 and 28,000. Precise figures are hard to compile because not everyone released from quarantine is registered.

In Beijing many companies have sent their employees into self-imposed home quarantine to prevent the contamination of the entire staff.

China remains the nation worst-hit by Sars, reporting 138 more cases and eight new fatalities yesterday, raising its death toll to 214.

Hong Kong said that it had six more dead — pushing its tally to 193. However, only nine new cases of infection were reported there, adding to hopes that the worst might be over.

Over-60s in the greatest danger

Nearly half of those over 60 who are admitted to hospital with Sars are likely to die, according to a British expert (Nigel Hawkes writes). That is a far higher death rate than anybody had previously suggested. The death rates in Hong Kong and Singapore have risen above 10 per cent, and Professor Roy Anderson and colleagues from Imperial College, London analysed data from the Hong Kong outbreak. They conclude in a paper published online today that among those over 60, 43.3 per cent can be expected to die.

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