HPV: one dose of vaccine already protects against cervical cancer

The protection provided by the single dose is as robust as the regimen of two or three applications. (Photo: Archives/Piratini Palace)

One dose of the HPV vaccine is enough to provide strong protection against cervical cancer. The conclusion is the World Health Organization’s Strategic Advisory Group of Experts on Immunization (SAGE). This is expected to increase vaccination coverage and be a game-changer for disease prevention.

According to the group, the protection against HPV, the virus that causes cervical cancer, provided by a single dose of the vaccine is comparable to the two- or three-dose regimens currently in use.

Cervical cancer is considered a “silent killer”, almost entirely vaccine preventable. However, globally, uptake of the vaccine has been slow and low, according to the WHO. In 2020, global coverage with two doses was only 13%. A virtually insignificant number compared to the 90% coverage target.

Contributing factors include delivery and scheduling difficulties, costs associated with delivering two doses, and the relatively high cost of HPV vaccines, especially for middle-income countries.

In Brazil, the vaccine is offered by the National Vaccination Program (PNI) for girls aged 9 to 15 and boys aged 11 to 14. Even so, two-dose vaccination coverage is low. In 2020, the index was 40% for girls and 30% for boys. On the other hand, the coverage of the first dose was higher, especially among girls: 70%. For boys, it was only 40%.

More than 95% of cervical cancers are caused by sexually transmitted HPV, which is the fourth most common cancer in women worldwide, with 90% of these women living in low- and middle-income countries.

In Brazil, the association that many parents make between the vaccine and the start of sexual life is another factor that hinders adherence to the immunizing agent.

In a bid to increase vaccination coverage and eliminate cervical cancer, SAGE recommends a one- or two-dose schedule for girls aged 9-20 years and two doses, 6 months apart , for women over 21. Previously, the recommendation was at least two doses.

Immunocompromised people, including those living with HIV, should receive three doses if possible and at least two doses if not. There is limited evidence on the effectiveness of a single dose in this group.

“I firmly believe that eliminating cervical cancer is possible. This single dose recommendation has the potential to move us faster towards our goal of immunizing 90% of girls at age 15 by 2030,” said Dr Princess Nothemba (Nono) Simelela, Deputy Director General of the WHO.