Although increasing numbers of studies confirm that human papillomavirus (HPV) vaccination is safe, non-specific symptoms and diagnoses continue to result in scepticism towards this vaccination. An innovative research approach was used to investigate vaccination safety by examining a possible link between vaccination and girls’ absenteeism from school. The researchers conclude that HPV vaccination does not increase the risk of illness manifesting as school absenteeism.
HPV vaccination has been part of Denmark’s childhood vaccination programme since 2009 and aims to protect girls from HPV infection and thereby cervical cancer later in life. Although numerous studies have found that this vaccination is very safe, many recent stories about serious side-effects of HPV vaccination have caused severe setbacks in national vaccination programmes.
“In Japan, this has had major direct effects, since they have stopped recommending this vaccination, and the United States has difficulty achieving high coverage. In Denmark, we have had a very special situation with media coverage in connection with HPV vaccination and a documentary on vaccinated girls aired by TV2 in 2015 in which several young women reported disabling symptoms after being vaccinated. Unfounded accusations are problematic, since this vaccination protects against cervical cancer, which means that some of those who are not vaccinated will get cervical cancer and may end up dying from it,” explains Anders Hviid, Professor and Senior Researcher, Department of Epidemiology Research, Statens Serum Institut, Copenhagen.
Difficulty with non-specific symptoms
Diagnosing people who experience symptoms after vaccination can be difficult. The most commonly reported symptoms include fatigue, headaches and dizziness. Since the reported symptoms are rarely specific, investigating the causes of the symptoms using databases and registries is more challenging than for more classic diagnoses with well-known symptoms and guidelines.
“Many studies have investigated the safety of HPV vaccination, and many of these have focused on specific concerns, such as whether vaccination is associated with blood clots. In this case, however, addressing these concerns with specific diagnoses was difficult. We therefore tried to find other ways to address this, and our study is then based on this rather unique method of examining girls’ absenteeism from school,” says Anders Hviid.
Innovative investigative approaches
The researchers used a unique registry in the City of Copenhagen that records children’s absenteeism from primary and lower-secondary schools. They linked sickness absenteeism data from more than 14,000 girls in grades 5–9 from 2013 to 2018 with data on HPV vaccination.
The study was based on the hypothesis that, if HPV vaccination is associated with an increased risk of having non-specific symptoms, then this will result in more school absenteeism from illness than among the unvaccinated girls.
No association with absenteeism
“We found that the HPV-vaccinated girls had exactly the same pattern of absenteeism as the unvaccinated girls. The lack of any difference shows that vaccination is basically really safe. This broad measure that considers all illness and not just specific disease diagnoses supports offering HPV vaccination in Denmark’s vaccine programme,” concludes Anders Hviid.