Table 4.

 Prevalence, incidence, annual incidence, and persistence or redetection of infection with HPV types 16 or 18, or both, in 2185 female students, of whom 821 (38%) returned follow-up samples after a median of 16 months. Values are numbers and percentages (95% confidence intervals)

HPV genotype	Prevalence (infected at baseline)	Incidence (new infection at follow-up)*	Estimated annual incidence	Persistence or redetection (same HPV type at follow-up)
				In women with same HPV type at baseline†	In all women with follow-up samples*
16	118/2185 5.4% (4.5% to 6.4%)	45/775 5.8% (4.3% to 7.7%)	4.2% (3.1% to 5.6%)	11/46 24% (12.6% to 38.8%)	11/821 1.3% (0.7% to 2.4%)
16, 18, or both	159/2185 7.3% (6.2% to 8.4%)	50/758 6.6% (4.9% to 8.6%)	5.3% (4.0% to 6.9%)	13/63 21% (11.5% to 32.7%)	13/821 1.6% (0.8% to 2.7%)

*Follow-up 11–32 months (median 16 months) from recruitment.

†Follow-up 12–23 months (median 16 months) from recruitment for HPV16 alone and for HPV16, 18, or both.