Sunday, January 31, 2010

Herd Immunity for Cerivical Cancer by HPV

When we went over herd immunity in class i was instantly intrigued, and it seemed to make a lot of sense, but i was thinking about it and i got a little bit curious what the percentage of the population would have to be vaccinated against the strains of Human Papillomavirus(HPV) that we have vaccines for until those strains were eliminated from the population via herd immunity. This is especially important when you consider that these two strains of HPV account for over 70% of cervical cancer from HPV.

Although countless hours of scientific journal research did not give me a percentage, it did lead to an interesting model that was made before the HPV vaccine that predicts the correlation of a HPV vaccine and the effects it would have on the number of cases of Cervical Cancer. The model assumed a 90% efficacy (the current vaccine is ~100%)with 70% of girls getting it at the age of 12. This study found the vaccine would decrease the overall HPV infection by 95.4%. It also found that cervical cancer would decrease by 61.8%. Keep in mind, this is only vaccinating girls, and they made a model for the vaccination o both boys and girls, but the boys results were largely insignificant in comparison.
So in terms of eliminating HPV entirely through herd immunity, i would estimate, that it would be between 70-80% of the would population would have to be vaccinated to eliminate the two strains of HPV that we currently have a vaccine for.


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