WHO Releases H5N1 Report
"INFLUENZA RESEARCH AT THE HUMAN AND ANIMAL INTERFACE"
The report summarizes the findings of the working group of 22 influenza researchers. The group met in September to discuss the pandemic potential of influenza, in particular H5N1, and the implications for public health.
In brief, findings relevant for those involved in corporate pandemic planning are:
The H5N1 virus continues to evolve, in humans and animals.
Much more research is required (in all areas including diagnosis, vaccine, drugs for treatment)
A reduction in pandemic risk is unlikely in the near future.
Detection of H5N1 infected birds in Kazakhstan, at the Caspian Sea in spring 2006, and in Qinghai Lake, China, earlier this year, is worrying. It is possible that the explosive westward spread of the virus seen in the winter of 05/06 may be repeated.
Current H5N1 vaccines in development may not protect against newly evolved strains. In addition, as there are so many unknowns, national stockpiling of pre-pandemic vaccines may be premature.
Scientific findings are:
Birds now shed more of the virus in their respiratory secretions than previously (however the virus is still shed in feces).
Whether domestic cats play a role in transmission of the virus to humans requires more investigation.
There may be a genetic susceptibility in some people, which would explain the observation that in clusters of human-to-human transmission those infected are direct blood relatives, whilst those related by marriage escape the disease.
People older than 50 years of age may be less susceptible to H5N1 infection. This may be due to their immune status (less "cytokine" response or perhaps some protective antibodies from previous influenza infections).
Differing patterns of H5N1 resistance to antiviral medications exists, and must be continued to be monitored.
Mortality rate in a pandemic:
H5N1 infection in humans currently has an extremely high mortality rate (approximately 60%).
If H5N1 "reassorts" with human seasonal influenza, resulting in a pandemic influenza virus, the death rate would probably not be as high.
However, the virus may remain "avian" and yet adapt to be easily transmitted between humans. If this occurs, the current mortality of approximately 60% may continue.
Whether such a high mortality would result in the virus being unable to sustain a pandemic is unknown. |
