Tests of contacts of other cases are in progress. The mode of transmission is far from elucidated, but the few cases identified in spite of the intensive surveillance in place in Hong Kong indicate that the virus does not transmit readily. However, influenza A viruses, in particular, are notorious for their facility to mutate. The Hong Kong Department of Health is conducting several epidemiological studies to ascertain the mode of transmission but more cases and time will be needed to draw conclusions. Unless the epidemiological situation changes significantly, WHO will not signal the need to develop a vaccine.
Work is in progress to identify a suitable strain of seed virus for vaccine production.
It would take several months to produce vaccine for distribution in large quantities. In the meantime, two antiviral drugs, amandatine and rimantadine, have been shown to be effective when taken in the early phase of illness. In parallel with the intensive epidemiological and laboratory investigations, Hong Kong has introduced a series of public health measures aimed at the import, handling and sale of live poultry, information to the general public, education in schools and child care centres, and enrolling all hospitals, health clinics and private physicians to ensure early detection of suspect cases. WHO together with WHO Collaborating Centres are working closely with the Government of Hong Kong to support its efforts to contain the spread of the H5N1 virus. The five-member team of epidemiologists from the WHO Collaborating Centre on site will be reinforced by two staff members from the Division of Emerging and other Communicable Diseases, Surveillance and Control at WHO headquarters and from the WHO Office for the Western Pacific Region arriving on 18 December.