Table 2.

Prevalence of Multiple HPV Infections at Enrollment among Sexually Active Women in the Costa Rica Vaccine Trial (n = 5412) a

Number of coinfecting HPV types	Observed number of women (O)	Poisson Expected number of women (E)	O/E (95% CI)
0	2933	2488.4	1.18 (1.14–1.22)
1	1409	1933.5	0.73 (.69–.77)
2	646	751.1	0.86 (.79–.93)
3	267	194.6	1.37 (1.21–1.55)
4	102	37.8	2.7 (2.2–3.3)
5	39	5.9	6.6 (4.7–9.1)
6	12	0.8	15.8 (8.2–27.6)
7	2	0.1	23.7 (2.9–85.6)
8	2	0.01	243.9 (29.5–881.2)

NOTE. ^aAnalyses were restricted to 25 HPV types genotyped using SPF10/LiPA. Women with untyped HPV types (n = 459) were excluded.