HPV vaccination to protect against cervical cancer: no increased risk of multiple sclerosis

29.01.2015 12:17

Serial vaccinations to protect against cervical cancer do not increase the risk of multiple sclerosis (MS) or similar nerve diseases. Two serious studies have now confirmed this in quick succession. “We neurologists can recommend vaccination against the human papilloma virus HPV to girls and young women with a clear conscience, because protection against cervical cancer does not come at the price of disease risks to the nervous system,” explains Professor Heinz Wiendl from the German Society for Neurology (DGN). Up to 45 percent of girls between the ages of 12 and 17 take advantage of the vaccination paid for by health insurance companies.

MS is a chronic autoimmune disease in which the coverings of nerve cells are attacked. The course varies greatly between patients, but is always associated with major limitations and in many cases leads to a deterioration in health and even death over several years. With more than 180,000 patients in Germany and more than 2 million worldwide, MS is one of the most common serious neurological diseases. Cervical cancer accounts for around 2 percent of all new cancer cases in women.

Soon after the vaccine against HPV was approved in 2006, there were several case reports of MS diseases within a short period of time. “It was unclear at the time whether these were simply coincidences. However, numerous media reports led to uncertainty: Newly ill MS patients suspected a connection with their vaccination, and many young women or their parents have since asked about the safety of the vaccination," says Heinz Wiendl, describing the experiences from his clinic. “This is a long-running issue,” says the director of the Clinic for General Neurology at the University of Münster.

Study of almost 4 million women

To investigate the controversial trigger theory, epidemiologists led by Nikolai Madrid Scheller from the Statens Serum Institute in Copenhagen evaluated the disease data of almost 4 million Danes and Swedes between the ages of 10 and 44 for the years 2006 to 2013. 800,000 of these women had received a widely used HPV vaccine (Gardasil®) during this period, allowing researchers to compare the incidence of MS before and after vaccination. Of a total of 7,622 new cases, only 163 occurred in the first two years after an HPV vaccination. Before vaccination, there were an average of 22 MS diseases per 100,000 person-years - after vaccination, this value was significantly lower, namely 6 MS diseases per 100,000 person-years. Scientists have also studied other conditions similar to MS that also attack the coverings of nerve cells. The same picture emerged here, as these “demyelinating” diseases were observed 16 times per 100,000 person-years before vaccination, compared to 8 times after vaccination.

Vaccination has no protective effect against MS

However, these numbers do not mean that the vaccine would protect against MS. Rather, the imbalance arises from the fact that MS and similar diseases usually only develop in women in the second decade of life, while the vaccination age is usually between 10 and 15 years. In a correction calculation, the researchers therefore adjusted their numbers according to the natural age distribution of MS. The probability of developing MS after an HPV vaccination turned out to be just as high as without vaccination. The data, like others before it, suggest a “favorable safety profile” with regard to the MS risk of the vaccine, write Scheller and colleagues in the journal JAMA. Due to the size of the study, the results are likely to be transferable to the situation in similar countries.

Different method – same result

A study in Southern California that used a different method to look for a possible connection between MS and various vaccinations also came to essentially the same conclusion. “Annette Langer-Gould, the leader of this study, is a very good epidemiologist and this study is very important,” says Professor Ralf Gold, one of the most renowned MS researchers in Germany, director of the Neurological Clinic at the University of Bochum and first chairman of the German Society for Neurology.

Langer-Gould and her colleagues had all of the insurance company Kaiser Permanente Southern California's medical records for the years 2008 to 2011 examined by an MS specialist for neurological abnormalities and compared with the data from vaccinations, especially against HPV and hepatitis B. The researchers then compared the 780 cases with MS or other demyelinating diseases with a fivefold number of controls - insured people who were as similar as possible to the sufferers in terms of age, gender and place of residence.

“This comparison also found no connection between a vaccination against HPV or vaccinations in general with the risk of suffering a demyelinating disease within three years,” says Professor Bernhard Hemmer, Director of the Neurological Clinic at the Technical University of Munich. However, a closer look showed that the risk of being diagnosed with MS or a similar disease in the first 30 days after vaccination was more than twice as high for vaccinated people under 50 years of age than for non-vaccinated people.

“These data speak against a causal connection,” explains Hemmer. It is more likely that in people with an existing underlying illness, a vaccination could accelerate the transition to visible symptoms. “Such a transition can also be initiated by any natural infection – for example with cold viruses.” However, in contrast to most natural diseases, a vaccination provides long-lasting protection. “Overall, vaccinations against HPV reduce the risk of cancer, and these studies clearly speak against an increased risk of developing MS and similar diseases,” emphasizes Hemmer.