Despite being effective and invaluable weapons against several different types of cancer, the vaccines for HPV have received a lot of undeserved negative attention. Perhaps that’s because there’s a stigma attached to HPV, given that it’s the most common STI. Alternatively, it could be due to misinformation spread about vaccines in general, but in particular about one of the HPV vaccines, Gardasil, which was wrongly attributed to numerous deaths during its trial (the real causes were things like drowning and malaria).
Regardless, as ars technica points out, uptake has been disappointedly low in some countries—particularly the United States—and it’s time that changed, especially since we now have an even more powerful weapon on our side: Gardasil 9. This new vaccine protects against five more strains of HPV than its predecessor and seven more than the first HPV vaccine Cervarix. It’s just been put through its paces in a huge trial, and the positive results showcase its effectiveness.
According to the study, this vaccine has the potential to prevent around 90% of cervical cancers and might even be suitable for use in boys, which could further reduce the incidence of cancers associated with HPV. The results of the trial have been published in NEJM.
Human papillomavirus (HPV) is not one virus, but a group of more than 150 related viruses. It’s the most common viral infection of the reproductive tract and most sexually active people will be infected at some stage in their lives. Although many types of HPV don’t cause problems, a small percentage of infections with certain types can persist and lead to cancer. At least 13 are known to be able to cause cancer, which are the so-called high risk, or oncogenic, types.
Almost all cases of cervical cancer are attributable to HPV and two types in particular, HPV-16 and 18, cause 70% of cervical cancers. But it’s not just women that are affected. HPV-6 and 11, for example, cause genital warts in men and women, and some types have been associated with other cancers, such as mouth, anus and penile cancer.
The first HPV vaccine to be invented, Cervarix, addressed 16 and 18, but it was followed shortly by an improved version, Gardasil, which bestowed added protection against 6 and 11. Now, scientists have added five more oncogenic HPV types to the vaccine, producing the most effective agent yet.
This new vaccine, Gardasil 9, was tested on more than 14,000 women between the ages of 16 to 26. Because an effective vaccine already exists against HPV, it was considered unethical to compare the new vaccine against a placebo, so the study used the earlier Gardasil instead.
Participants given Gardasil 9 were found to have the same amount of protection against the strains that Gardasil defends against alongside additional protection against other genital cancers. Overall, Gardasil 9 has the potential to protect against 90% of cervical cancers, a 20% improvement on Gardasil. Given that the new virus contains more bits of virus, side-effects were more common in those given Gardasil 9, but these were generally minor, such as pain at the injection site.
Taken together, Gardasil 9 seems to be a promising addition to our ever-growing vaccine arsenal, and further studies will shed light on whether it would also be useful in boys.