As at 17 April, a total of 1,297 patients have been admitted to public hospitals with Severe Acute Respiratory Syndrome (SARS). Of these, 307 (23.7%) are health care workers or medical students while 990 (76.3%) are patients, family members or visitors/contacts. A total of 272 patients (20.3%) have recovered and been discharged from public hospitals, of whom 15 were discharged on 17 April. There are 65 fatal cases.

2.　　　　　　　A cluster of suspected SARS cases related to Koway Court, Chai Wan was first reported to the Department of Health (DH) on 9 April. Up to 17 April, there were 12 confirmed SARS cases in which 10 were residents from two blocks of Koway Court and 2 were working in Koway shopping mall. These cases included 6 males and 6 females, with age ranged between 4 and 72. The date of onset of the first case was traced back to 25 March. The onset dates for the other confirmed cases were between 3 and 12 April. Extensive epidemiological and environmental investigations are being conducted to contain the spread of the disease. Preliminary findings show that this cluster is not similar to Amoy Gardens in terms of magnitude and case pattern. The situation is being closely monitored.

3.　　　　　　　When a passenger who has traveled on board recently is confirmed to have SARS, DH will initiate a contact tracing exercise to prevent further spreading of the disease. Between 25 March and 10 April, DH has initiated such exercise on a total of 14 flights, and as at 15 April, 545 passengers and crewmembers from these flights were successfully contacted. Of these, 15 passengers involving 3 flights were confirmed to have SARS and 12 of them were members of tour groups. On 16 April, another contact tracing exercise was initiated for flight CA117.

4.　　　　　　　The Airport Authority was notified of the situation and all concerned flights arrived and departed from Hong Kong were cleaned and disinfected.

5.　　　　　　　As of 15 April, there were a total of 321 SARS cases in Amoy Gardens. There was an obvious concentration of cases in Block E, accounting for 41% of the cumulative total. The rest of the cases (59%) were scattered in 14 other blocks. In terms of onset dates, the outbreak reached its peak on 24 March and declined steadily afterwards. Block E cases appeared earlier in the outbreak and showed a point-source type of distribution. Cases in other blocks, which appeared 3 days later, were more evenly spread out in time.

6,　In order to identify the cause of the outbreak of SARS at Amoy Gardens, the Government have conducted a detailed investigation covering epidemiological, environmental, public hygiene, building design and utilities considerations. The major findings of the investigation were announced on 17 April.

7.　　　　　　　In gist, the findings showed that not one single factor could account for the outbreak in Block E of Amoy Gardens and that the outbreak was likely to be the result of a combination of factors, including: -

The presence of an index patient who caused the first batch of infections;

Person-to-person spread;

Transmission via the sewage system; and

Environmental contamination.

8.　　　　　　　The report found it probable that the index patient suffering from chronic renal failure had infected a group of residents in Block E and subsequently other residents in the same block through the sewage system, person-to-person contact and the use of communal facilities such as lifts and staircases.

9.　　　　　　　Observations from some research studies report that some people with compromised immune systems can excrete copious amount of viruses. The report also noted a swab sample taken from the toilet of an infected resident had shown positive in the test for the corona virus! & Genetic material.

10.　　　　　　　Like other blocks in Amoy Gardens, Block E has 33 floors with 8 apartment units on each floor. Eight vertical soil stacks of each block extend along the height of the building for each of the 8 units. Each soil stack collects effluent from the water closets, the basins, the bathtubs and the floor drains of the toilets of all the units that it serves. Each of these sanitary fixtures is fitted with a U-shaped water trap to prevent foul smell and insects in the sewers from entering the toilets.

11.　　　　　　　For the U-trap to function properly, it must be charged with water. However, the investigation found that the U-traps of the floor drains were dried up in many cases because most households had the habit of cleaning the bathroom floor by mopping instead of flushing it with water. Indeed, in tests carried out in one of the Block E units, reflux of air from the soil stack into the bathroom through the floor drain was demonstrated when the exhaust fan in the bathroom was switched on. It is postulated that the reflux could have contained droplets of contaminated sewage present in the soil stack, be dispersed into the bathroom, and be extracted by the bathroom exhaust fan into the light well between adjacent units. The contaminated droplets could then enter other units through open windows.

12.　　　　　　　The contaminated droplets could deposit virus on various surfaces, such as the floor mat, towels and other bathroom equipment. The chance of exposure was increased given that the bathrooms in the apartment units of Amoy Gardens were generally small in size (about 3.5m2.) Records from the management office confirmed that there were numerous complaints from residents on the emission of foul gas from the floor drains indicating the likelihood of the failure of the U-traps in these apartments.

13.　　　　　　　The report also observed that the infection had spread among close contacts, e.g. family members, although this is a smaller contributory factor to the overall outbreak.

14.　　　　　　　Air samples, potable water samples and other environmental swabs were collected in Block E to identify the extent of contamination brought about by the infectious agent. Air and water samples showed no evidence of contamination. These laboratory test results together with the spatial and temporal distribution of cases in Amoy Gardens and the epidemiological picture argue against airborne transmission or transmission through contaminated water.