U.S. researchers see evidence of herd protection against oral human papillomavirus (HPV) infections in men and women who did not receive the HPV vaccine.

In the U.S., HPV vaccination has been recommended for females since 2006 and since 2011 for males to prevent anogenital HPV infections and related cancers.

Vaccine. Source: Getty

Prevention of oral HPV infections and oropharyngeal cancers is not a vaccine indication, although studies have shown that the HPV vaccine is effective in reducing the prevalence of oral HPV infection.

To look for evidence of herd protection against oral HPV infections in unvaccinated men and women, the researchers used four cycles of the National Health and Nutrition Examination Survey (NHANES) to generate nationally representative data on oral HPV infections in the U.S. from 2009 to 2016.

During the study period, HPV vaccination rates increased from 0% to 5.8% in men and from 7.3% to 15.1% in women, report Dr. Maura Gillison of the MD Anderson Cancer Center, in Houston, and coauthors in a paper online September 10 in JAMA.

In unvaccinated men, the prevalence of vaccine-type oral HPV infections (those included in the vaccine) declined by 37% between 2009-2010 and 2015-2016 (from 2.7% to 1.6%), suggestive of herd protection against oral HPV infections, they say.

There was no change in prevalence of nonvaccine-type HPV infections in unvaccinated men.

Oral HPV infections in unvaccinated women remained unchanged for both vaccine- and nonvaccine-types. "The lack of herd protection toward oral HPV infections in unvaccinated women could reflect low statistical power due to low prevalence in women," the authors write.

The use of self-reported information on HPV vaccination is a limitation of the study, they note. Also, there was low statistical power to investigate herd protection stratified by different ages.

Based on their findings, they say "estimated herd protection should be incorporated into evaluations of the cost-effectiveness of HPV vaccination of men older than 26 years. Vaccine trials of oral HPV incidence and persistence in men should inflate sample sizes to account for herd protection."

The study had no commercial funding.

SOURCE: http://bit.ly/2UKIUYU

JAMA 2019.