Laura Bush
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On April 17, the US Food and Drug Administration announced the approval of the first US vaccine for humans against the H5N1
strain of influenza (see story). This is important good news. As of March 8, 2007, there have been 277 confirmed human cases
of avian flu reported to the World Health Organization, and 168 of those infected have died. According to the WHO, the next
pandemic is likely to result in 1 to 2.3 million hospitalizations and 280,000 to 650,000 deaths in industrialized nations.
Its impact is expected to be even more devastating in developing countries.
If an avian influenza virus mutates to a form able to spread effectively between humans, we will be in dire straits. Current
worldwide vaccine production capacity is theoretically about 900 doses per year, enough to vaccinate only 10 to 15% of the
world's population with a single dose. If two doses were needed, that coverage would be cut in half. The other big concern
is whether we could manufacture vaccine quickly enough to protect the population before the outbreak had already taken its
toll.
The new vaccine, made by Sanofi-Pasteur, isn't a perfect defense, of course. Only 45% of the individuals who received the
vaccine in the trial developed antibodies at a level believed to be sufficient to reduce the risk of contracting avian flu.
But the current body of knowledge suggests that even suboptimal antibody levels may reduce disease severity, hospitalization
levels, and deaths. And most important, the new vaccine would buy us time in the event of an outbreak, by creating some resistance
while a vaccine is developed against the specific pandemic strain. If we had nothing to prop up the doors while the vandals
approached, those months would be very scary indeed.
The other part of the good news is that Sanofi-Pasteur's vaccine is not an isolated advance. Many other manufacturers are
working to develop their own. Several aim to reduce dosing requirements through using advanced adjuvants and delivery systems.
San Diego–based Vical, for example, has developed an adjuvant that showed a 60-fold increase in antibody response and a 10-fold
lower dosage requirement in early testing of a seasonal flu vaccine; the hope is that these benefits will be seen when the
technology is applied to pandemic strains. Baxter (Deerfield, IL) just completed Phase 1/2 studies showing that its pandemic
flu vaccine may be effective even at low doses, without an adjuvant. And the Dutch company Crucell just received a European
Commission–funded grant to fund preclinical and clinical testing of pandemic flu vaccines being developed by a consortium
of nine universities and companies. Some of these vaccines target other avian flu strains, such as H9N2.
In March, the FDA released its strategic plan for pandemic influenza preparedness, which addresses the areas of the Health
and Human Services Plan for which FDA is responsible; key elements include working with industry to help ensure sufficient
manufacturing capacity is available and to accelerate the time for new product approvals. The European Union has its own programs,
including the FLUPAN collaboration among several government agencies, universities, and industry.
We still have a long way to go to protect the world against pandemic flu. It is encouraging, however, to see these important
steps forward.
Laura Bush is the editor in chief of BioPharm International, lbush@advanstar.com
