What happened to women who had been vaccinated against the human papillomavirus more than 10 years ago? A study in the United States showed that they have less cancer than those who did not. The incidence can be reduced by 18% with a single dose.
The study, one of the largest on the subject, was published in "The Lancet Child and Adolescent Health."
The bad reputation that the vaccine won against the human papilloma was a shameful number. After a coverage of 91.4% in 2013, the figure dropped to 20.4% in 2014, after what happened in El Carmen de Bolívar. Several girls who received the human papilloma vaccine, as part of the government's free vaccination day, were recorded by the media with severe headache, dizziness and fainting, symptoms they and their families attributed to the vaccine, but that the National Institute of Health prompted denied that they were "episodes of psychogenic cause". (Reading: vaccine against human papillomavirus is safe, according to study)
But despite the fact that in the country the images of the girls were sufficient to stigmatize the vaccine, Scientific documents continue to take major steps to prove the opposite. One of the largest studies in the United States, which collected data from more than a decade ago, found that the vaccine is an effective method to reduce the number of cases of cervical cancer, even if it is applied up to 20 years old.
This conclusion recently came to a study that has been published in The Lancet Child and Adolescent Health, in which two groups of women were analyzed: those who had been diagnosed with cervical intraepithelial neoplasia – precancerous cells in the cervix – and another of healthy women.
The database that the study took was that of a group of women who are part of the Kaiser Permanente study of the health system of California (United States), in which women are up to 26 years old. In particular, the researchers looked for data about women diagnosed with CIN2 and CIN3., the two most advanced types of neoplasms, between January 1995 and June 2014, taking into account the fact that the human papilloma vaccine entered the American system in 2006.
Then they looked for a control group of women who were the same age as those who were diagnosed and who had the exams in the same year, but did not find any injury. To guarantee the validity of the results, For every woman who had CIN2 or CIN3, they tried to have five women with similar characteristics, but no injuries. (You can read: The human papillomavirus can be related to different types of cancer)
With these data in hand, the scientists followed the vaccination schedules of both groups, based on three important criteria: whether they had received a vaccine against the human papilloma, whether they had all three doses – as recommended – and the age at which they had been vaccinated. that the first dose was applied (between 14 and 17 years old, between 18 and 20 years old and older than 21 years).
To make sure that conditions such as ethnicity, if they smoke, if they used hormonal contraceptive methods or had children, would not influence the research, they adjusted the statistical model.
After carrying out the models, the scientists found different conclusions. The most important of these is perhaps that the vaccine is still effective when the first dose is given before the age of 20, whereas if the vaccination starts between 21 and 26 years, the effectiveness is greater low. "
"The evidence suggests that the protection is more powerful as the vaccine is started faster. After 21 years, the evidence about the effectiveness is not clear. Other research in other settings will now be needed to evaluate the effectiveness of vaccinating women aged 21-26 years, "said Michael Silverberg, a scientist at Northern California's Kaiser Permanente Research Division in Oakland, in a statement. the study. (Also read: Vaccine against human papillomavirus can not be mandatory: constitutional court)
Moreover, the research confirms what the scientists already suspected: that overtaking the three doses makes the vaccine even more effective. They also found that the incidence of cancer decreased by 18% when the woman has taken at least one dose.
Therefore, when an anti-vaccine movement is fired worldwide, this study becomes an important part of the scientific effectiveness of the vaccine against human papillomavirus. "This is one of the few studies and larger scale that have analyzed the effectiveness of the vaccine when it is placed after 17 years", explain the researchers. And they add that it may be useful to support the vaccination guidelines of some countries, where it is recommended to catch up with this vaccine between 15 and 20 years.