The two vaccines used for HPV protect against 4 strains of the virus which are most known to cause cancer. There are more than 40 other types of the virus, however, and scientists are beginning to worry that these types will become stronger as the vaccine fights off the four others.
Researchers are just beginning to look into this possibility to see if it has any implications for new HPV infections. A preliminary study published just this month looked at over 2,000 men in Kenya who have HPV to see how many types of the virus most people were infected with. The study showed that being infected with one type of the virus is not related to being infected with any other type. This shows that there is not a concerning amount of competition between the types of viruses.
The next, and more important, step is to see whether there is a difference between the number of types of HPV in a person before they are vaccinated and after they are vaccinated. This will show whether targeting the four types that we now target could put people at risk of infection from the other types of HPV.