Catching up on some old but still under-discussed news, here’s an interesting article published on the Proceedings of the National Academy of Sciences Web site a couple of months ago. The researchers’ strategy was to conjugate an antigen from the malaria parasite to a larger protein, then use that as a vaccine. Here’s the twist: the antigen is only expressed in the mosquito stage of the malaria life cycle, so people who get such a vaccine wouldn’t actually be immune from malaria.
So what’s the point? Well, if a vaccinee got malaria, then got bitten by a mosquito, the insect would drink antibodies as well as the parasite. When the parasite tried to continue its life cycle in the mosquito to get to the next host, the antibodies would take it out. In other words, vaccinees could still get the disease, but they wouldn’t pass it on to others. If it works as well in humans as it appears to in monkeys, this could be a very clever way to control one of the world’s deadliest diseases. But are people really altruistic enough to accept a vaccine like that?
Check out Galvani, Alison P. et al in the March 27th issue of PNAS (vol. 104/#13): Long-standing influenza vaccination policy is in accord with individual self-interest but not with the utilitarian optimum.
It has to be in the individual’s interest to be immunized, protecting others doesn’t seem to work. And, interestingly, CDC’s influenza immunization policies are all off: the elderly are well-immunized because they’re at greatest risk but young people spread the disease. If 77% of the young were vaccinated, influenza would be wiped
The new malaria vaccine is cool but perhaps there should be more incentive for people to get it –perhaps combining it with another protective antigen.
Marcy