The rate of HPV (human papillomavirus) infection in the anal region affects 52% of young Brazilians between 16 and 25 years old who have already started their sexual life, with a higher prevalence among women (63.2% compared to 36.8% among men ).
The results, obtained by Sheetare from the first national survey on the subject, carried out at the request of the Ministry of Health, and show an anal infection rate very similar to that in the genital region (58.6%).
HPV involves a group of more than 150 viruses, of which at least 13 are associated with various types of cancer, such as cervical, anus, penis and head and neck cancer.
The work was part of a large national survey on the impact of the HPV vaccine available in the SUS since 2014 for girls and boys aged 9 to 14. In this current stage, 12,800 young people from all Brazilian regions were evaluated.
Led by Hospital Moinhos de Vento, in Porto Alegre (RS), through Proadi (SUS Institutional Development Support Program), the research should support the ministry in new actions to reinforce immunization.
In recent years, the country has faced a decline in HPV vaccination coverage. In 2022, among girls, the first and second doses had, respectively, 75.91% and 57.44% adherence.
Among boys, the numbers are even lower: 52.26% in the first application and 36.59% in the second. This year’s data is not yet consolidated.
The quadrivalent vaccine is indicated for the prevention of genital warts (HPV 6 and 11) and tumors related to HPV 16 and 18, such as those of the vulva, vagina, cervix, anus, oral cavity, trachea and penis.
According to the research leader, Eliana Wendland, an epidemiologist at Moinhos de Vento, the high rates of anal HPV infection were surprising. “We’re talking about an extremely young population that is at risk of developing anal cancer.”
HPV infection is associated with 90% of cases of anal cancer, a type of tumor that has been increasing in several countries in recent decades.
In the United States, in 15 years, the growth rate was 3% per year, and there is already a proposal to screen for anal cancer in the same way as is done today for cervical cancer.
Contrary to what many people imagine, HPV infection in the anus is not directly related to the practice of anal sex. It also happens among those who do not practice it.
“Other studies outside Brazil have already shown that women who did not have anal sex had a similar rate of anal HPV infection to that of genital HPV. We can infer that, due to the proximity of these regions, infection can occur in different sites”, says Wendland.
Other studies outside Brazil have already shown that women who did not have anal sex had a similar anal HPV infection rate to that of genital HPV. We can infer that, due to the proximity of these regions, infection can occur in different places
In relation to men, the explanation is similar. “In the population assessed, few had anal sex, but they had HPV infection in the region. It could be contamination during sex. In other words, you don’t need to have anal sex to have anal HPV.”
She states that, in half of the women evaluated, the type of HPV found in the anal region was at high risk for cancer. “That’s a lot,” reinforces the doctor. Among men, the rate was 29%.
“The research brings something important, which is to show the population that HPV is associated with cancer in other regions, such as the anal region, and that the vaccine is not just against cervical cancer. It is a vaccine against several types of cancer which can affect men and women”, says Eder Gatti, director of the PNI (National Immunization Program), of the Ministry of Health.
The study demonstrated a positive impact of the quadrivalent vaccine on anal HPV infection rates. Among those vaccinated, the rate was 3.1% and among those not immunized, 10.9% (for the virus serotypes present in the vaccine).
In the private network, there is another vaccine formulated with nine serotypes. The price of a dose is between R$800 and R$950 — in adults, the recommendation is three applications.
According to the study, the types of HPV contained in the nonavalent vaccine also showed a significant reduction in infection rates: from 30.2% to 24.7%.
For the epidemiologist, the results reinforce the need to intensify HPV vaccination among men and women and to think about screening strategies for this young population. “Using HPV detection techniques for both cervical and anal cancer.”
The country has been studying a change from the current cytology (Pap smear) to the molecular technique for detecting HPV. “This makes me screen people at risk. When I do cytology, I’m screening a person who already has a lesion.”
Data on the national study on HPV were presented last week, in Porto Alegre (RS), and must still be published in a scientific journal.
They represent the second phase of a project started in the 2015-2017 three-year period, through Proadi, in which the rate of genital and oral HPV infection was assessed in a population of unvaccinated young people between 16 and 24 years old.
Now, in the 2020-2023 period, the study analyzed young people from this same age group to check the rate of infection in the genital and anal regions between those vaccinated and those not vaccinated.
According to Wendland, the results show a significant reduction in infection by all types of HPV contained in the quadrivalent vaccine.
When comparing data from those who were not vaccinated with those who were vaccinated, genital HPV infection rates fell from 15.6% to 3.6%.
Wendland says that the vaccine available in the SUS also proved to be effective for other types of HPV (in addition to the four present in the vaccine). “It’s what we call a cross-reaction. The HPV viruses have a genetic and structural similarity. When I vaccinate against types 16 and 18, there is an impact, albeit smaller, on 33 as well.”
Gatti, from PNI, says that the research results will support the ministry in actions to combat the drop in HPV vaccination coverage.
According to him, the current management has launched fronts to reverse this trend not only in relation to the HPV vaccine but to all immunizations covered by the PNI, including the multi-vaccination campaign and direct action with municipalities with the development of regional strategies aimed at local challenges.
“The municipality needs to leave the vaccination room and vaccinate where the unvaccinated are, in their homes and in the school environment.”
He states that, based on these actions, there is an expectation that the vaccination rate among adolescents has already shown some sign of improvement this year, especially in relation to vaccines against HPV and meningitis (meningococcal ACWY). The data for 2023, however, is not yet finalized.
Another front, explains Gatti, is the unification of two information systems that gathered information about vaccination onto a single platform, called RNDS (National Health Data Network).
Fake news surrounding the HPV vaccine presents another challenge, according to him. Among the coping strategies, the ministry has been monitoring what is published in the press and on social networks and providing quick responses to prevent the spread of fake news.
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