The WHO plan directs a single-dose HPV vaccine to increase vaccination

In December 2022, it was released from (Global Health Organization) Post a new plan In order to eradicate cervical cancer, the focus is on vaccination against human papillomavirus (HPV), a virus that can cause warts or cancer (tumor tumor) depending on the type. The new guidelines suggest reducing vaccine doses for children and adolescents, in order to increase the reach of the target population of the vaccination regimen. In Brazil and other countries, the HPV vaccine is administered in two doses to children and adolescents between the ages of 9 and 14.

Article HPV vaccination programs at LMIC: time for improved schedules and recommendations?published in Journal of Pediatrics It was produced by researchers Luisa Villa and Rosanna Richtman, respectively, from University of the South Pacific College of Medicine (FMUSP) and Infection Institute Emilio RibasReviews studies on the efficacy of a single dose in different age groups and the applicability of this new WHO recommendation. The work noted positive findings in the literature on the effects of single doses in vaccination programmes.

Human papillomavirus is a virus that causes a sexually transmitted infection, causes warts in the tissues of the mouth and genitals, and depending on the type of virus, can cause cancer, such as cancer of the cervix, vulva, vagina, penis, anal canal, and others. The HPV vaccine is being implemented in the public health system, primarily focusing on individuals who have not yet begun their sexual lives; In Brazil, immunization began in 2014—at that time, for girls only—on two doses of the quadrivalent vaccine, which protects against types 6 and 11 (which cause warts), and types 16 and 18 (of oncogenic origin). Today, vaccination is also extended to boys from nine to fourteen years old.

when the vaccine was approved [em 2006]Clinical trials sought to apply three doses: the first dose tells the body that you are receiving a different antigen and begins to trigger a unique response, the second is another response trigger, and the third is a booster dose. It was the three doses that proved that the vaccines work well to prevent infections and diseases, not only in the cervix, but also in the anus – and now there are indications for the oral cavity, in both women and men.explains Luisa Lina Villa, Professor at FMUSP. However, when they noticed that the immune response was more efficient in the younger population, the number of doses was reduced to 2 doses in children and adolescents, and remained at 3 for adults and immunocompromised subjects.

New studies show that a single dose will be sufficient for children and adolescents, because the immune response in this group is so strong that applying just one dose would really help expand vaccine coverage. The recommendations of the World Health Organization and the researchers’ article are based on the findings of a study conducted in Kenya Washington University, with women ages 15 to 20, who received just one dose of the vaccine, and this has been shown to be 98% effective in preventing HPV infection. Other studies in India and Costa Rica have shown that a single dose has a similar protective effect as two or three doses.

The main goal of this change in the vaccination schedule is to reach as many people as possible before the age of 15, a stage in which immunogenicity (effective immune response) is still very high and who, presumably, have not yet begun their sexual life. A single dose could mean lower immunization costs, simplified implementation, greater vaccination adherence, and increased coverage with the same percentage of protection against cancers attributable to HPV infection.

Brazilian scenario

In Brazil, adherence to the HPV vaccine does not reach the level recommended by the World Health Organization, which is 90% for girls between the ages of nine and fourteen. According to a study by the Cancer Foundation, with data from 2013 to 2020, 76% of the target audience took the first dose and only 56% took the two doses stipulated in the Brazilian vaccination schedule. For boys, the numbers are even lower, with only 52% vaccinated with the first dose in 2022.

Luisa Villa points out that the biggest challenge in Brazil is not the number of doses. “Our limitation is that people are afraid to take the vaccine or that mothers don’t take their babies. We need a great deal of work to raise awareness, discussion and comment that the vaccine is safe and effective, and that it should be taken so that we can see a reduction in tumours, not just malignancies, such as cancer, but also benign ones.”

She also warns that men should also be vaccinated, because the risk of cancer is not limited to cervical cancer for women, but to other types such as infections of the genital tract, anal canal, mouth, and non-cancerous infections. Vaccination coverage of this type helps fight infection and reduce the incidence of cancer.

with information from USP Journal.