People had been vaccinating against rabies for a while (at least since 1893), using nervous tissue from animals infected with an attenuated strain of the virus, but apparently this wasn't always perfect, and could be difficult to obtain.
Some people had been experimenting with preserving rabies virus by freeze-drying it. They found that this method could preserve the virus's infectivity for months or even years. But in the current study, D.L. Harris found that even after the freeze-dried virus lost its infectivity, it still retained some of its immunogenicity, the ability to induce an immune response. This disappeared after a while too, though, so there was a range in which it could be used as a vaccine. However, since there was a chance that it was still slightly infectious, it had to be given in conjunction with the regular vaccine to make sure there was no chance of contracting rabies from it; a sort of vaccine against the vaccine.
This doesn't seem all that useful to me, but apparently Harris went ahead and tried it on about 3500 people and a bunch of dogs and other animals. The people had all been bitten by a potentially rabid animal, so they didn't have much choice for treatment, and apparently the vaccine worked just fine in all except one, who had received a nasty bite but refused the full course of treatment so he could get back to work. The side effects in people were limited to short-lived local redness and swelling.
It seemed to work well prophylactically in animals too: of hundreds of dogs and some rats, only one rat died in the study but it wasn't clear that it was from rabies, and it seemed to be 100% effective in protecting rats against infection (of 16 vaccinated and 8 controls, zero got rabies of the former and 4 of the latter died of it).
So according to Harris, this vaccine gives better protection, but it seems like the disadvantage of requiring an extra dose of differently prepared vaccine makes it not quite perfect. More improvement needed.
Citation: Harris, D. L. Antirabic Immunization with Desiccated Vaccine. Am J Public Health Nations Health 19, 980–985 (1929).
No comments:
Post a Comment