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12 years after HPV vaccination, women are still protected against cervical cancer

The HPV vaccine once discussed has been shown to work as intended for longer than previously documented.

This is shown by a large Nordic study in the medical journal The Lancet. The vaccine protects against human papillomavirus (HPV), which can cause cell changes in the cervix and lead to cervical cancer.

– We have followed a large number of women who have received the vaccine to look at the duration of protection against cell changes in the cervix caused by HPV types 16 and 18. For at least 14 years after the vaccination there were no cell changes, concludes chief physician Susanne Krüger Kjær, who is co-author of the study.

Researchers have followed the results of women̵

7;s routine cancer examinations and do not measure cell changes for at least 12 years. After 14 years, the trend is the same.

However, it is only during the first twelve years that the database is large enough to draw conclusions.

The researchers also measured the antibodies that are formed against HPV. The vaccine provides a stable level of antibodies for at least 14 years.

Followed the women for 14 years

To investigate the effect, the researchers conducted a new study, in which 12,167 women from 13 countries received the HPV vaccine or placebo, before the effect was followed for four years.

In the new study, the researchers followed 2121 participants from Denmark, Iceland, Norway and Sweden by keeping an eye on the countries’ screening programs for cervical cancer.

In Denmark, women are offered screening every three years when they are between 23 and 49 years old.

At the same time, the subjects took blood samples during the research project, which the researchers analyzed.

Thus, they have tested the vaccine’s ability to get the immune system to produce antibodies that protect against HPV infection (types 16 and 18), which is the cause of 70 percent of all cases of cervical cancer.

Since all the women in the study had been vaccinated, the researchers needed another comparison group to replace a placebo group.

They solved this by comparing how often Nordic women who had not been vaccinated had cell changes on the cervix.

The long-term effect of the vaccine is important

Although there is already solid scientific evidence for the effect of the HPV vaccine, it is important to document the sustainability of the effect, says Susanne Krüger Kjær.

– Duration is a very important factor, as some vaccines need to be renewed after a few years. Our results show that this applies here, says Kjær, who is a professor at Rigshospitalet.

She is a research leader at the Department of Viruses, Lifestyle and Genes at the Danish Cancer Society’s center for cancer research.

The fact that duration is important to document is supported by Jan Blaakær. He was involved in the original study that the new study has followed up and has read the new study.

The excipient in the vaccine is also used in hepatitis vaccines and the effect is not reduced there. But we had to document it, says Blaakær, who is chief physician and clinical professor of gynecology at Odense University Hospital and the University of Southern Denmark.

But even if the vaccine is effective, you still have to be screened for cervical cancer, he emphasizes. In the study, no serious cell changes produced by HPV16 and 18 have been found, but the virus is found in several different types that can cause cell changes and cervical cancer:

– HPV 16 and 18 are the cause of 70 percent of all cases of cervical cancer, so it is 30 percent that has not been covered. Therefore, women must of course continue to be screened even if they have received the vaccine, says Blaakær.

Severe cell changes

Virtually all women who have been sexually active will get an HPV infection. In most people, the infection disappears on its own without symptoms, but in some the infection becomes chronic and the women are at risk of developing serious cell changes and, in the worst case, cervical cancer.

Cell changes may be less severe in the sense of “far from creating cervical cancer” (called CIN 1), potentially more serious (called CIN 2) or so severe that the woman is at greater risk of developing cervical cancer (CIN 3) if the cell change is not treated. .

The new study shows that the HPV vaccine reduces the risk of all three steps, but most effectively CIN 3.

Source: HPV vaccine impresses in new studies: May even exceed researchers’ hopes

An expected result

The new result fits in with the existing knowledge about the vaccine, confirms chief physician Karsten Juhl Jørgensen, head of the Nordic Cochrane Center at Rigshospitalet in Copenhagen.

– We knew that the HPV vaccine was effective against pre-stages of cervical cancer and that antibodies were being developed. It is a longer follow-up than before, but nothing revolutionary, he writes in an e-mail.

Normally, one would be critical of the researchers’ use of a historical control group instead of giving placebo, but since the effect was mostly 100 percent against relevant virus types, it is not the big problem here, Jørgensen believes.

Financing of the pharmaceutical industry

One thing you can be critical of is that the study is funded by the company Merck Sharp & Dohme Corp, which is behind the Gardasil vaccine.

The close connection between the researchers and the company can breathe life into conspiracy theories, says Karsten Juhl Jørgensen:

– When it comes to vaccines, credibility is crucial, and one should be careful about pouring water on the vaccine opponents’ use, he believes.

Only the pharmaceutical industry can afford to fund such extensive studies.

And even if it is not optimal, there is no reason to believe that the financing has affected the results, Jan Blaakær believes.

– The ideal would be if it was not the industry that financed it, but they can not go in and cheat with data, he says.


Susanne K. Kjaer et al: «Final analysis of a 14-year long-term follow-up study of the efficacy and immunogenicity of the quadruple human papillomavirus vaccine in women from four Nordic countries», Lancet, 2020, DOI: 2020.100401

FUTURE II Study Group: «Quadrivalent human papillomavirus vaccine to prevent high-grade cervical lesions», New England Journal of Medicine, 2007, DOI: 10.1056 / NEJMoa061741

© Videnskab.dk. Translated by Lars Nygaard for forskning.no. Read the original case on videnskab.dk here.

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