While we are all waiting for the other shoe to drop and a nasty, rip roaring flu pandemic to come rushing down the tracks at us, lots of companies have jumped into the pandemic vaccine sweepstakes. Reuters reports that at least 16 companies are testing flu vaccines and probably even more are involved in some technical aspect of vaccine production. That’s good, although whether it will make any significant difference except around the margins remains to be seen. Timing is everything.
Meanwhile, though, work is going forward on many vaccine fronts. The one to hit the PR wires today is a report that Iomai Corporation out of Maryland has shown in a small human trial involving 500 people that combining their adjuvant skin patch with a single injection of containing 45 micrograms of H5N1 antigen is sufficient to stimulate a level of antibody considered protective in 70% of the subjects. Whether that level is too high, too low, just right or irrelevant we won’t know until the balloon goes up, but that’s a problem all the vaccines have — testing to see if they would really work in the real world infections. The big advance here is that unlike other schemes, this one involves only one injection. The 45 microgram injection requires much more antigen than some competitors, but it is really equivalent to two 22.5 microgram injections and only has to be given once, a tremendous advantage in a pandemic setting. The only licenses pre-pandemic H5N1 vaccine in the US has 90 micrograms of antigen and has to be given twice.
The patch is applied to a the subject’s skin after it has been lightly abraded with a sandpaper like material. The patch itself has 50 micrograms of some material (not identified in the news reports) and was tested with an egg-based vaccine, but the company says they believe it could be used with other vaccines after suitable testing. They also claim the patch has a 2-year shelf life (and so could be stockpiled) and “treavels” well. These are essential characteristics for practical distribution and use in a crisis.
What are some of the other vaccine problems that various people are trying to solve? Antigen-sparing technologies, like adjuvants (non-vaccine additives that boost the immune response when given with the vaccine) is one big area, and the patch is a version of this. But another important effort is to try o get away from egg-based vaccines. There aren’t enough eggs, not enough production facilities, not enough time. There is a lot of work on this now, commonly involving growing viral antigen in tissue culture or bacteria. This has the potential for much faster turn around after a pandemic strain has been identified, a faster production ramp up and easier scale up and even replication and dissemination of small production facilities. Other work focusses on trying to find the Holy Grail of flu vaccines, a vaccine that works across all strains and subtypes — the universal flu vaccine.
This is a crowded and competitive field. No one knows if there will be enough time to figure out something that is safe, effective and feasible.
And even if there were enough time, how would we vaccinate the population when we have a broken down and failing public health system? Ah, that’s still another problem. Unfortunately it’s not one we are working on.