Asian Influenza A (H5N1)—
Now is the time to prepare
by David M. Bookout, MD
2006 DCMS President
The Dallas County Health and Human Services’ presentation in the EPI report of the March Dallas Medial Journal is an excellent review, and I encourage you to keep it for reference. As I read the article, I thought of all the recent publicity about Avian H5N1. My initial impression was that the dangers of a pandemic were extremely small. After all, this is a bird and poultry disease, and it affects distant areas of the world. Few cases have been diagnosed in humans and definite human-to-human infections are minimal. Why should we be concerned?
The World Health Organization described a recent pattern of rapid geographical spread of the H5N1 virus in wild and domestic birds. There are major concerns that migratory birds are spreading avian influenza. JAMA (Vol. 295 No. 5) reported only 146 human cases, with 6 deaths. They extrapolate from the 1918 pandemic that killed 20 million to 50 million people in a less populated planet. Modeling studies indicated that 500,000 to 1 million Americans could die during an avian pandemic. Another concern involves mutation of the virus, which could enhance the human-to-human transmission. If this were to occur, then international travel could enhance the spread.
The means of transmission are: (1) animal to animal, (2) human to human, and (3) environment to human. In animal-to-human transmission, the human usually has close contact with infected poultry, especially ill or dying chickens. Human-to-human transmission is through close physical contact, but the exact method is unclear. Environmental transmissions include ingestion of contaminated water during swimming, direct intranasal or conjunctival inoculation during exposure to water, contamination of hands from infected fomite, and exposure to untreated poultry feces used as fertilizer.
The March 30, 2006, New England Journal of Medicine reported testing of a new vaccine. The report indicated that a higher dose of the vaccine would be required and only 54% of the subjects who received two shots 28 days apart developed an immune response. The good news is that side effects were minimal.
Drug treatment is limited. Both Amantadine and Rmantadine are ineffective; however, the neuraminidase inhibitors (oseltamivir and zanamir) are effective. Prophylactic treatment is beneficial, decreasing shedding of the virus. However, it is not beneficial if given late.
The federal government has set aside $6.7 billion for its influenza plan, distributed as follows: $5.3 billion for cell-based vaccine technology and stockpiling the experimental vaccine, and $1.4 billion for stockpiling oseltamirir. Despite the promise of the plan, there is a history of mismatch of public needs and the private production of vaccines. You only have to recall the 2004-2005 vaccine shortage when the United Kingdom withdrew a corporate license as a result of a bacterial contamination. Several disincentives for manufacturers inhibit vaccine development: high investment costs, limited or variable markets, and regulatory compliance. Manufacturers are leaving the industry, creating the risk of shortages. Only four of the 26 companies in the US market that were producing vaccines in 1967 are still in the market, and only two of these companies are domestic. All these factors do not bode well for availability of an effective vaccine in the future. Recognizing the need, the G7 Finance Ministries announced a pilot advance market commitment for vaccines of public health importance.
Even if the vaccines are available, distribution to the population is problematic. Pandemic influenza would require mass vaccination within a short time. This would require federal stockpiles and a system for transportation, storage, and safe administration of the vaccine. This system does not currently exist.
The vaccine industry faces multiple hurdles. These include state and national regulations, issue of personal properties, and liability. The likelihood of having a fully tested vaccine available is low and the chance of reactions to the virus likely. The Vaccine Injury Compensation Program compensates patients and provides liability protection, but this needs to be improved. Healthcare workers and patients would be less likely to volunteer without a fair compensation system, as the failed smallpox vaccination campaign demonstrated.
Allocation of a scarce resource is always an ethical problem. In the short term, we can expect an almost certain extreme shortage of the counter measures. Facilities are not available to produce adequate amounts of vaccines or new medication.
The most challenging bioethical question is, “Who shall live when all cannot live?” Should a lottery or a “first come, first served” system be used? Considering the devastating social and economic ramifications of a pandemic, other rationing criteria are worth consideration. A pilot project found stakeholders and citizens at-large at a high level of agreement. They chose a functioning society and reducing deaths as priorities in vaccine allocation. Although this altruistic consensus is comforting, it may not reflect real behavior in a time of crisis.
After consideration of the multitude of issues involved in preparation for a pandemic, I realize it is imperative that this potential should be used to design systems that would be applicable to other disasters. Now is the time.
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