Table 1.

Incidence of HPV-6, HPV-11, HPV-16, and HPV-18 infections

HPV-6 (n = 953)HPV-11 (n = 995)HPV-16 (n = 895)HPV-18 (n = 963)
Mean person-years at risk3.03.23.03.1
Cases/total person-years at risk103/2,88913/3,188142/2,64562/3,007
Incidence per 100 person-years (95% CI)3.6 (2.9-4.3)0.4 (0.2-0.6)5.4 (4.5-6.3)2.1 (1.5-2.6)