Clinical Trial for H5N1 Bird Flu Vaccine

Since the virus was first detected in Guangdong Province, China in 1996, H5N1 (Bird Flu) has received much attention as the fear of a global spread of the disease mounted. Initially, H5N1 was considered merely interesting; however, alarm bells began to ring when it spread through live-poultry markets in Hong Kong, and eventually to humans, in 1997. The virus killed 6 of 18 infected people.

Now, a published clinical trial of a whole-virus H5N1 vaccine derived from a cell culture raises new hopes for a vaccine against the deadly virus.

Since 1997, we’ve determined that the virus continues to evolve and mutate. In an effort to control spread of the disease, millions of birds have been slaughtered and disposed. Thus far, 45 countries have reported Bird Flu outbreaks. The virus is endemic in dozens of species of birds in South Asia, and is threatening to become endemic in west Asia and Africa.

Currently, it is very difficult for humans to become infected with H5N1; however, intermittent spread to humans will continue as the virus evolves. The current number of confirmed cases of Bird Flu reported to the World Health Organization (WHO) as of May 2008 is 383 cases. Of these, 241 have died.

The whole-virus vaccine was created using a strain from A/Vietnam/1203/2004 obtained from the CDC and inactivated. The vaccine was manufactured in Vero cell culture.

The results as published found that,

… the vaccine induced a neutralizing immune response not only against the clade 1 (A/Vietnam/1203/2004) virus strain but also against the clade 2 and 3 strains.

The researchers conclude that

this may be a useful H5N1 vaccine.

The study raises hopes that a vaccine will be available should the (some say) inevitable come to pass, and we are faced with a pandemic the likes of which we have not seen in a long time. But who will decide who gets the vaccine if and when the time comes? Currently, our ability to manufacture a flu vaccine is not great enough to supply the vaccine to everyone. Although this issue is being addressed, it will likely become an issue of contention.

Pandemic planning is aimed at getting the vaccine to “front-line” workers first, as these people will be necessary to controlling the spread of the disease; for example, health care workers who will be caring for victims of the flu, and the military, who will be charged with keeping the peace among citizens.

Will our public health measures be adequate in the face of an epidemic? What will the role of health care workers, and their obligation, be? When it is inevitable that the number of sick far outnumber the workers that are available, what ethical obligation will health care workers be held to?

And what of countries who will not be able to afford to vaccinate their citizens? What will they do? Will our government step in and provide the vaccine to them? Or, will it become a matter of the “haves” and the “have-nots,” with developing countries being left to fend for themselves (as they too often are)?

Likely, when the time comes, the fact that a vaccine is available will not be a guarantee that everyone will have equal access to it.

References

Ehrlich, H.J., et al. (2008). A Clinical Trial of a Whole-Virus H5N1 Vaccine Derived from Cell Culture. NEJM, 358(24), 2573-2584.

Cumulative Number of Confirmed Human Cases Of Avian Influenza A (H5N1) Reported to WHO. May 28, 2008.