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Researchers find a possible overlap between symptoms before and after the HPV vaccination

A new study from Aarhus University shows that girls who are referred to one of Denmark’s HPV centres had already visited the hospital more frequently when compared to other girls who were also HPV vaccinated. Furthermore, some of the most frequent diagnoses among the girls who were referred are similar to the most common suspected HPV side effects.

2019.03.07 | Ida Skytte

[Translate to English:] Fem HPV-centre blev i kølvandet på mediehistorier om alvorlige bivirkninger ved HPV-vaccinen oprettet for at tage sig af de ramte piger. Nu viser ny forskning – igen – at pigerne var syge allerede før de fik vaccinen.

Already before being HPV vaccinated, girls who had been referred to Denmark’s five HPV centres were more often hospital patients. This is the result of a new study register-based study from Aarhus University.

"There is no doubt that the girls who are referred are ill. However, we’ve found that some of them were more frequently at the hospital even before they received the vaccination," says Lene Wulff Krogsgaard, who is a PhD student at Aarhus University and the main author of the study, which has just been published in the scientific journal Vaccine.

She explains that the girls who were later referred to an HPV centre had also had more contact with the hospital already and both more and a wider range of diagnoses than the girls who were not referred.

 “This may indicate that the girls who were referred have had a higher degree of symptoms which have been difficult to find a clear-cut cause for. Alternatively, they may have had several different conditions which required treatment. In other words, they stood out before they received the vaccination,” she adds.

Overlap between diagnoses

According to the researchers, another interesting finding is that some of the diagnoses are consistent with the most commonly reported side-effects after the HPV vaccination, including e.g. headaches, non-specific muscle-related illnesses and gastro-intestinal problems.

“We’ve taken a systematic look at the most common hospital diagnoses before the HPV vaccination. For the diagnoses where we find the strongest correlation, there is an overlap with the symptoms which are reported as possible side effects following the vaccination. For this reason, we can’t rule out that some of the girls who were referred may already have had similar symptoms before they received the HPV vaccination,” says Lene Wulff Krogsgaard.

The new research results are based on data from 1,496 girls who were referred to one of the Danish regions’ five HPV centres in 2015.

Eighty per cent of the referred girls had been in contact with a hospital at least once during the preceding years, and 24 per cent of them had been in contact six times or more. The control group consisted of 7,480 vaccinated girls of the same age who had not been referred to an HPV centre. Among this group, 65 per cent had been in contact with a hospital at least once and twelve per cent had been in contact six times or more.

The big HPV puzzle

The new study confirms previous research in the area. Research from Denmark’s Statens Serum Institut (SSI) has shown the same picture, and another study from Aarhus University based on the same study population showed that girls referred to the HPV centres had more often been receiving psychiatric treatment prior to the vaccination compared to those girls who were not referred.

“Finding an explanation for why so many of them become ill is rather like doing a big jigsaw puzzle. Our study is an important piece, but we still don’t have the whole explanation,” says Lene Wulff Krogsgaard.


The research results – more information

  • Type of study: Register-based case-control study
  •  External partners: Medical doctors at the Danish HPV centres.
  •  External funding: The Danish Cancer Society and the Danish Health Foundation.

 The scientific article is published in the journal Vaccine:



PhD student Lene Wulff Krogsgaard
Aarhus University, Department of Public Health
Telephone: (+45) 2621 9896
Email: l.krogsgaard@ph.au.dk

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