The human papillomavirus vaccine also protects the unvaccinated

A study published in the

suggests that vaccination against the human papillomavirus (HPV) is associated with a reduction in the prevalence of genotype 16/18 infection among women born in the decade of the 90s compared to those of a previous decade.

In addition, the analysis emphasizes that vaccination can also benefit those who have not been immunized due to what is known as the herd effect.

According to the publication of the study, whose main authors are the researchers Zahed Shahmoradi and Ashish A. Deshmukh of the Research Center of the University of Texas,

Steady improvements in coverage of this vaccination over the past decade may have translated into benefits for the contemporary birth cohort (ie, women born in the 1990s compared to the 1980s).

"To measure whether HPV vaccination has been associated with reduced infection rates among recently vaccinated (vaccine-mediated immunity) and unvaccinated (herd protection) women, we compared HPV prevalence in birth cohorts in the 1980s versus the 1990s and in a prevaccination period versus a more recent period.

Valentín Pineda, member of the Vaccine Advisory Committee of the Spanish Association of Pediatrics and pediatric infectious disease specialist at Hospital Parc Taulí in Barcelona, ​​explains that "what this study shows is that the cohort of women born in the 1990s have more protection against HPV than those of the 1980s due to vaccination.

The direct effect is clear.

This cross-sectional study analyzed data from two cycles (2005-2006 and 2015-2016) of the National Health and Nutrition Examination Survey (NHANES), on a stratified sample of the US civilian population, including demographic characteristics, vaccination immunization , race and ethnicity collected by interviewers.

.

The prevalence of HPV-16/18 infection -the oncogenic types covered by the vaccine- was estimated for two birth cohorts: women born in the 1980s (1980-1989) and in the 1990s (1990-1998). .

To estimate the efficacy of HPV vaccination, the prevalence of infection before the introduction of the vaccine (2005-2006) and recently (2015-2016) was calculated from NHANES data.

"Given that the 1990s birth cohort was 26 years old or younger in 2015 and 2016, we limited the comparison to the 18-26 age groups," the researchers write in the article.

Thus, the

.

HPV prevalence among participants born in the 1990s was significantly lower than among those born in the 1980s.

During the 2015-2016 cycle, 55% of women aged 18 to 20 years, 52% of those aged 21 to 23 years, and 50% of those aged 24 to 26 years had received one or more doses of the vaccine against HPV

.

Among women aged 18 to 26 years, the prevalence of HPV before the introduction of the vaccine (2005-2006 cycle) was 15.2%.

In the recent period (2015-2016), this percentage had decreased to 3.3% overall, 5.1% among the unvaccinated, and 1.0% among the vaccinated groups.

In addition, the prevalence of infection in the recent period (2015-2016) was 0% among women aged 18 to 20 years.

The probability of infection, in half

The estimated probability of HPV infection was 54% lower for women born in the 1990s than in the 1980s

.

Similarly, the estimated probability was 78% lower overall during the 2015-2016 cycle compared to the 2005-2006 cycle;

more specifically, 60% lower for the unvaccinated and 92% lower for the vaccinated.

Estimated probabilities were lower for the 1990s (vs. 1980s) and recent (2015-2016) birth cohorts vs. the pre-vaccination period (2005-2006) taking into account race and gender. ethnicity, number of lifetime number of sexual partners, and country of birth.

In this sense, Dr. Pineda points out that, according to this part of the study focused on the two time cycles, "the percentage of infection also decreases in unvaccinated women and this can only be due to the herd effect. That is,

; not as much as if they are vaccinated, but they do benefit".

The results of the study suggest that HPV vaccination was associated with a reduced prevalence of HPV-16/18 infection in a recent birth cohort of vaccinated and unvaccinated women aged 18 to 26 years.

For Xavier Bosch, emeritus researcher at the Catalan Institute of Oncology (ICO), principal investigator at the Bellvitge Biomedical Research Institute (IDIBELL) and professor of Health Sciences Studies at the Open University of Catalonia, "it is a population-based study of interest using appropriate methodology It is very consistent with all the most recent analyzes in Australia, Sweden and the United Kingdom, which

[cervix] cancer in vaccinated women, particularly when vaccination has place before the age of 17. The results are as expected and add information in the United States, which they will surely monitor in the future".

He further adds that

, data that we had from phase III studies, but that we are now accumulating in population-based public health conditions. It is a very interesting and satisfactory study."

Furthermore, this study provides a birth cohort perspective and

.

In any case, the researchers note that the study is limited by the use of self-reported HPV vaccination status and the exclusion of HPV types not covered by the vaccine.

"The authors are aware of the limits of these studies (for example, they acknowledge the potential for error in asking people about their HPV vaccination, rather than directly reviewing official records confirming whether or not vaccination occurred They

do

," concludes Bosch.

The study concludes by noting: "Historically, in the US, the prevalence of HPV infection among women has followed a log-normal distribution pattern, with a peak observed in the young age groups. This fundamental concept may need to be reassessed to HPV-16/18 infection, given the recent peak shift we've seen."

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