RESEARCHERS working on the Sars virus here have discovered that the disease is a double-edged sword.
The good news: It is not passed on by people who show few or no symptoms of the disease, unlike other coronaviruses.
However, someone struck by Sars is more likely to die from it because, when it does hit, victims suffer a full-blown attack.
'These results are extremely important to the scientific community, so we can be better prepared in case of a second attack,' said Dr Pierce Chow, consultant surgeon in Singapore General Hospital's (SGH) department of surgery and a lead researcher in the study.
Next month, the ground-breaking work will be published in the journal Emerging Infectious Diseases, a publication by the United States Centres for Disease Control and Prevention.
A team from SGH, DSO National Laboratories and the National Environment Agency studied blood and stool samples from 87 health-care workers who had been in surgical wards which were quarantined after the first Sars outbreak last April.
Looking at antibodies present in the samples, they found that only Sars patients had developed antibodies to it. So, those who showed no symptoms did not have Sars and would not pass it on.
Its freakish nature stems from it being a new mutant in the virus world, explained Dr Chow.
'Older viruses like influenza are highly infectious even when the carrier doesn't seem sick yet. This is how they've evolved to spread and survive.
'But because Sars is relatively new and not adapted to humans, it's more likely to kill its host, although that means it can't spread well either.'
He added: 'When Sars first struck, we were starting from ground zero and sometimes groping in the dark.
'Now we know the enemy better and know that our earlier safety precautions were correct.'
When it first hit, said Dr Chow, the whole SGH surgery department was closed down - half of the 60 doctors were on voluntary quarantine in case of infection and the other half moved to Tan Tock Seng Hospital to treat patients.
With one in 10 of the department's doctors trained as scientists, the group under quarantine devised their battle plans via e-mail and phone calls.
'We had the sudden realisation that nobody in the world was more knowledgeable than us,' said Dr Chow.
'In fact, the martian had landed in our backyard, and we were the experiment. If we hoped to defeat the disease, we would have to do our own research.'
A key member of the research team, medical officer Ong Kong Wee, volunteered to ferry stool and blood samples in his own car from the hospital to laboratories for testing.
'It was potentially very dangerous. Although we followed all the international guidelines, there was still a danger there could be a leak. That thought gnawed at the back of my mind,' he said.
To keep his wife and baby son from being infected, he stayed in a vacant apartment the family owned in the River Valley area for two months. But when they were finally reunited, it was a bittersweet moment.
'My son couldn't recognise me when I finally went home, I felt a bit like a stranger,' he said. 'But somebody had to do it.'