With flu season in the northern hemisphere looming and H1N1 cutting a nasty swath through good portions of the southern hemisphere’s current flu season, attention is being turned to the non-existent but hoped-for vaccine against swine flu. Yesterday we discussed the problem of pinning pandemic planning on a vaccine. That’s planning for the best, not hoping for the best. There are a lot of uncertainties regarding whether an unadorned egg-based vaccine — the bulk of the vaccine now in development — will be sufficient, available in time or even effective. But those problems just scratch the surface of vaccine unknowns, as a typically excellent piece by Helen Branswell of Canadian Press lays out:
Vaccine manufacturers will do the basic testing, work designed to assure regulators and would-be recipients that their vaccine is safe and likely to protect against the pandemic strain, an H1N1 virus of swine origin.
But there are many other key questions. In fact, the list is too long to tackle in its entirety in the limited time available.
So discussions between planners and regulators over the past few weeks have led to a paring down of priorities.
[NIH will reportedly] green-light one looking at whether the pandemic vaccine – to protect against the new H1N1 virus – could be given at the same time as seasonal flu vaccine, which protects against three types of flu viruses including a different H1N1.
Co-administration, as it is called, would make the logistics of pandemic vaccine delivery much easier – if the pandemic vaccine is ready in time. But would giving people vaccines that protect against two different H1N1 viruses at once actually undermine the effort by weakening the response to one or both?
In Canada, plans are underway to try to test whether people with egg allergies could be given flu shots containing vaccine produced in eggs. Currently that is considered unsafe and is not done.
Dr. Scott Halperin, a vaccinologist from Dalhousie University in Halifax, says a newly formed, federally funded research network hopes to get ethics approval to test the assumption it is unsafe to give people with egg allergies flu shots.
“That is a real concern,” he says of the current position on people with egg allergies. “You can’t leave a whole segment of the population without access to protection.”
Another question regulators in the United States and possibly some other countries need answered relates to the use of adjuvant.
Specifically, they’d like to know whether one of the powerful new adjuvants made by companies like GlaxoSmithKline and Novartis could be used with antigen (vaccine) made by a company that currently doesn’t market adjuvants, such as Sanofi Pasteur. (Helen Branswell, Canadian Press)
None of these studies will answer the bottom line question about whatever vaccine or vaccines emerge from the gauntlet of testing and unforeseen contingencies between now and any major ramp up of circulating swine flu, should this occur in the fall (as seems very likely). That question is whether the vaccine will make much of a difference. That’s something we don’t know yet. In theory, it should, but the evidence from seasonal flu is murky.
We won’t know how well it worked until afterward. One hopes that along with plans for a vaccine campaign there are also parallel plans for systematic evaluation of efficacy. One hopes. As always, Hope Springs Eternal.