A population-based study of human papillomavirus genotype prevalence in the United States: baseline measures prior to mass human papillomavirus vaccination

Abstract

Currently, two prophylactic human papillomavirus (HPV) vaccines targeting HPV 16 and 18 have been shown to be highly efficacious for preventing precursor lesions although the effectiveness of these vaccines in real-world clinical settings must still be determined. Toward this end, an ongoing statewide surveillance program was established in New Mexico to assess all aspects of cervical cancer preventive care. Given that the reduction in cervical cancer incidence is expected to take several decades to manifest, a systematic population-based measurement of HPV type-specific prevalence employing an age- and cytology-stratified sample of 47,617 women attending for cervical screening was conducted prior to widespread HPV vaccination. A well-validated polymerase chain reaction (PCR) method for 37 HPV genotypes was used to test liquid-based cytology specimens. The prevalence for any of the 37 HPV types was 27.3% overall with a maximum of 52% at age of 20 years followed by a rapid decline at older ages. The HPV 16 prevalences in women aged ≤ 20 years, 21-29 years or ≥ 30 years were 9.6, 6.5 and 1.8%, respectively. The combined prevalences of HPV 16 and 18 in these age groups were 12.0, 8.3 and 2.4%, respectively. HPV 16 and/or HPV 18 were detected in 54.5% of high-grade squamous intraepithelial (cytologic) lesions (HSIL) and in 25.0% of those with low-grade SIL (LSIL). These baseline data enable estimates of maximum HPV vaccine impact across time and provide critical reference measurements important to assessing clinical benefits and potential harms of HPV vaccination including increases in nonvaccine HPV types (i.e., type replacement).

Figure 1

Percent of cervical Pap specimens that are positive for any carcinogenic HPV type by the number of months since the previous Pap test. Specimens from women with no previous Pap test in the Registry are indicated as N. Pap specimens taken less than 10 months (< 300 days) after the preceding Pap test (darker shading) are not classified as screens and were excluded from analyses.

Figure 2

The age-specific prevalence of HPV in cervical Pap specimens. (A) The percent of specimens positive for any HPV type, any carcinogenic HPV type, and any low-risk HPV type. (B) The percent positive for any bivalent HPV vaccine type (16 or 18), any quadrivalent HPV vaccine type (6, 11, 16 or 18), and any nonavalent HPV vaccine type (6, 11, 16, 18, 31, 33, 45, 52 or 58). (C) The percent positive for any carcinogenic HPV type, any carcinogenic type other than 16 or 18, any carcinogenic type other than 16, 18, 31, 33, 45, and any carcinogenic type other than 16, 18, 31, 33, 45, 52 or 58. The specimen may be positive or negative for any of the excluded types.

Figure 3

Age-adjusted odds ratios and 95% confidence intervals for cytologic result of High Grade (HSIL, ASC-H, or AGUS) vs. Negative in specimens with HPV of specified type (single infection) compared to those without HPV infection. Numbers on right margin are the total number of single HPV infections of the specified type. No high grade results found in specimens with HPV types 69 (n=3), 64 (n=5), 26 (n=3), or 11 (n=2). Reference lines for odds ratios of 1, 5, and 10 are added for readability.