Studies on behavioral trends reveal that oral sex is highly common in several nations.”In a research my colleagues and I did in the UK, 80% of adults reported engaging in oral s3x at some point in their lives. The participants were almost 1,000 patients having tonsillectomy for non-cancer causes. But thankfully, only a few of those individuals develop oropharyngeal cancer. It’s unclear why that is, said Hisham Mehanna.

The prevailing theory is that most of us catch HPV infections and are able to clear them completely. However, a small number of people are not able to get rid of the infection, maybe due to a defect in a particular aspect of their immune system. In those patients, the virus is able to replicate continuously, and over time integrates at random positions into the host’s DNA, some of which can cause the host cells to become cancerous.

Many nations have implemented HPV vaccination programs for young girls in an effort to prevent cervical cancer. There is growing evidence that it may be successful in avoiding HPV infection in the mouth, even though it is still indirect. According to some data, “herd immunity” may also protect boys in nations with high vaccination rates for girls (above 85%). Together, these factors may, ideally, result in a decline in oropharyngeal cancer during the next few decades.

From the perspective of public health, that is excellent news—but only if girls are covered to a high degree—more than 85%—and only if one person stays in the “herd” of people who are covered.