Potency concerns for pandemic flu vaccine stockpiles; HHS planning update; more contracts awarded

For months, we've been discussing some of the many challenges and potential problems associated with the "pre-pandemic" avian flu vaccines currently being developed, tested, and stockpiled. More reason for concern came late last week, when this CIDRAP News story reported that a significant percentage of the stockpile has lost potency, resulting in a one-million-person decrease in the number of people who could potentially be protected by vaccine doses currently on hand (3 million, down from 4 million in an HHS document released in July). Here's an excerpt from the story, quoting an HHS spokesman:

"'All vaccines have shelf lives,' Hall told CIDRAP News. 'The early vaccine that was purchased, the first lots, have begun to lose their potency.'

He said the potency has begun to decrease for 'the majority' of doses in the stockpile, adding, 'That doesn't mean it goes from 100 percent to zero percent' or that the doses would be unusable."

On Friday, a day after the story above appeared, the same HHS spokesman seemed to walk back his earlier comments in this CIDRAP follow-up, explaining that only 20% of the current doses on hand are losing potency, not "a majority," as he previously said. Either way, it should come as a surprise to no one that these vaccines have a limited shelf life, an issue avoided by seasonal flu vaccines on account of their annual reformulations. Even with full potency, the vaccine doses in question are from "clade 1" virus samples from 2004. Since early this year, vaccine development has been based on a 2005 sample, working toward "clade 2" vaccines expected to be a closer fit to a possible pandemic strain.

All of this news came as a result of the release last week of the latest HHS Pandemic Planning Update. Not a lot of news in the 13-page report (and, thus, virtually no news coverage about its release), but it provides a good overview of the current status of U.S. planning and spending.

Finally, HHS announced today that another $200 million in contracts have been awarded to Sanofi Pasteur, Novartis, and GlaxoSmithKline for an additional 5.3 million doses of "clade 2" pre-pandemic vaccines, enough to vaccinate roughly 2.7 million people. (Here's the story from Reuters.) This would double the current stockpile (notwithstanding further decreases in potency of older vaccines), but still represent only a bit more than 1/4 of the goal of having enough vaccine stockpiled for 20 million Americans.

NIH/CDC working on 2nd avian flu vaccine

At the National Immunization Conference in Atlanta, HHS secretary Michael Leavitt announced today that the development of a second avian flu vaccine has begun, this one on a more recent isolate of the virus. CBSNews.com has the story.

The 'original' vaccine is based on a 2004 sample of avian flu from Vietnam. The U.S. government has already spent $250 million for 8 million doses through contracts with Sanofi Pasteur and Chiron, the story notes. The cycle of vaccine development announced today involves a 2005 isolate from Indonesia. As we've written previously, the question no one can answer is how effective (if at all) earlier vaccines will be against the eventual 'pandemic' strain of avian flu, whenever (or if ever) it arrives.

Ultimately, there's agreement in the scientific community that the only vaccine sure to be effective against a pandemic strain is one developed only after it arrives, requiring a minimum 6-month wait for any vaccine and all but certain supply shortages. At this point, the hope is that these vaccines currently in production will provide some measure of protection in the meantime, if necessary.

The question for public health experts and health economists is whether a semi-annual, $250 million payout for vaccines that may or may not be effective is a sound use of resources as part of preparations for a pandemic. For bioethicists, in addition to the host of issues relating to the allocation of scarce resources, etc., this announcement adds a new wrinkle to consider: If/when a pandemic arrives, it's now possible that several 'generations' of vaccine will be available, with newer generations progressively more effective against the virus than earlier ones. How should this be handled? A national triage system? A roll of the dice based on which manufacturer your physician/hospital/state purchases vaccine from?