According to a CRC briefing, the coronavirus in the prime suspect, but not proven.

"We continue to regard the new coronavirus as the leading hypothesis for the etiology of this condition. The evidence is mounting from a number of international laboratories, that this is indeed the case; but we are also exploring other potential viruses as are our collaborators, and we will keep you posted as we go forward on that part of the scientific investigation. A number of things are in progress, including sequencing of the whole virus genome, and we'll have more information on that, potentially next week or the week thereafter.

We are at a situation in time where we recognize that the disease is still primarily limited to travelers, to health care personnel who have taken care of SARS patients, and to close contact with SARS patients.

The affected travelers are those who have been in Hong Kong, in Hanoi, in Singapore, and in mainland China, for the most part.

We believe, based on what the investigations have shown us so far, that the major mode of transmission still is through droplet spread when an infected person coughs or sneezes and droplets are spread to a nearby contact. But we are concerned about the possibility of airborne transmission across broader areas and also the possibility that objects that become contaminated in the environment could serve as modes of spread.

Coronaviruses can survive in the environment for up to two or three hours ,and so it's possible that a contaminated object could serve as a vehicle for transfer to someone else."