STATEMENT FROM THE MINISTER FOR HEALTH
HEALTH MEASURES AGAINST SARS OUTBREAK

Current state of knowledge on SARS
The World Health Organisation (WHO) has stated that SARS is a serious threat to international health and could become the first severe new disease of the 21st century with global epidemic potential. So this is a very serious problem confronting Singapore and the rest of the world.

Let me start by summarizing what we know and what we do not know.

It is now six weeks since WHO first issued its global health alert on 12 March on cases of atypical pneumonia. For the Healthcare Workers (HCW) at the frontline combating SARS, this has been a long and demanding six weeks. But six weeks is a relatively short period for a completely new disease.

The WHO announced on 16 April that a newly discovered virus from the coronavirus family is the cause of SARS. Identification and characterization of the exact causative virus will allow development of better diagnostic tests and treatment protocols. A significant step towards this was the recent sequencing of the viral genome by scientists in the US, Canada, Hong Kong and Singapore.

We are learning more about the spectrum of clinical presentations. Most patients present with typical features with a sudden onset of high fever with or without muscle aches. Some patients may also have chills, shivering, cough and headache. After 3 to 7 days, patients may start to have shortness of breath, and X-ray changes of pneumonia. In about 80 to 90% of cases, the patient gradually recovers. However, in 10 to 15% of cases, after about 7 days, the pneumonia progresses and the patient needs treatment in the intensive care unit with most requiring a ventilator to help them breathe. About 6% of cases die despite intensive care. The majority of patients who succumb to the disease are older persons above the age of 40 years. But we have had 3 deaths from patients below 40 years.

We have observed a number of cases where the symptoms have not been typical. This has made the disease even more difficult to combat. This has occurred in patients with many pre-existing chronic medical conditions such as heart disease and bacterial infections that mask the symptoms and signs of SARS. In such cases, the fever may be low-grade at the beginning and signs of lung infection occur very late in the course of illness. Such cases are very difficult to recognise early and pose a major challenge for our healthcare professionals.

How is SARS transmitted? Both WHO and the US CDC believe that the main way SARS spreads is through transmission of infectious droplets, for example, when a SARS patient coughs or sneezes droplets into the air and someone else close by breathes these droplets in. Our own experience in Singapore supports this view since most of our cases have occurred either among healthcare workers caring for SARS patients in hospital, or family members and friends of the patients who had visited and come into close contact with them. Based on our experience, patients appear to be most infectious when they are ill. Most of the SARS patients in Singapore have passed on the infection to a small number of people only, and through close contact. However, we have also noted that there a small number of SARS patients who appear to be highly infectious, infecting a large number of people (super-spreaders). This may also have been due to the fact that their SARS illness had not been picked up earlier and they had infected a large number of persons in close contact with them by the time they were diagnosed with SARS. Hence, 5 SARS patients have been responsible for the transmission of the infection to the vast majority of the 182 non-imported patients that we have seen so far in Singapore (up to 23 Apr 03).

However, there may be situations where SARS may have been transmitted through other routes. For example, the outbreak involving a large number of residents in an apartment block in Hong Kong suggest that SARS may be transmitted perhaps through some common environmental route. Transmission through contaminated surfaces also cannot be ruled out. That is why we emphasise the need for a higher standard of personal and environmental hygiene.

So far, three diagnostic tests have been developed for SARS. However, all the tests have limitations. There is a test for antibodies to SARS in the blood. However, this is present only from about 20 days after the onset of clinical symptoms. It therefore cannot be used to detect cases at an early stage. The second test, an immunofluorescence assay (IFA), detects antibodies reliably as of day 10 of infection, but is a comparatively slow test that requires the growth of virus in cell culture. The third test is a molecular test for detection of SARS virus genetic material. This is useful in the early stages of infection but at this stage of development, the test kit fails to pick up many patients with SARS. WHO has stated that more work is needed to produce a robust test that is capable of rapidly and reliably detecting cases at an early stage of infection. Many laboratories, including those in Singapore, are working to achieve this.

There is as yet, no specific treatment for SARS. WHO has stated that no treatment beyond good intensive and supportive care has been shown to improve the outcome in patients with SARS. About 8-9% of our cases have died compared to the global average of 6%. The case fatality rate in Hong Kong has also been about 7% but that in Canada has been about 9%. A likely reason for the slightly higher fatality rate in Singapore compared to Hong Kong is that the daily occurrence of new cases here has been much lower than that in Hong Kong. In Canada, most of the fatalities have occurred among elderly patients with co-existing chronic illnesses.