Researchers from California found no long-term association between vaccines, including those protecting against hepatitis B and HPV, and increased risk for multiple sclerosis or other central nervous system demyelinating disorders, according to study results.
In the nested case-control study, the researchers extracted data from the electronic medical records (EMRs) of Kaiser Permanente Southern California. The investigators queried the EMRs for mention of diagnostic codes pertaining to multiple sclerosis (MS) and other central nervous system demyelinating disorders (CNS ADS) from January 2008 through December 2011. Inpatient and outpatient visits for these conditions among patients of all ages were identified for inclusion (n=780). For each incident case, up to five age- and gender-matched controls were identified (n=3,885). Ninety-two CNS ADS cases and 459 control patients were females aged 9 to 26 years — the recommended age range for HPV vaccination. The Kaiser Immunization Tracking System was used to identify vaccination records within 3 years of the index data, with any vaccination defined as an exposure.
The researchers found that HBV vaccination was not correlated with the risk for CNS ADS up to 3 years later (OR=1.12; 95% CI, 0.72-1.73), nor was there an association between 3-year CNS ADS risk and HPV vaccination (OR=1.05; 95% CI, 0.62-1.78) or any vaccination (OR=1.03; 95% CI, 0.86-1.22). An association was noted between vaccination of any type and 30-day CNS ADS risk in individuals aged younger than 50 years (OR=2.32; 95% CI, 1.18-4.57). According to the researchers, this short-term increased risk for CNS ADS after vaccination may suggest vaccines spur accelerated progression from subclinical to manifest autoimmunity in patients with existing disease.
“Our data do not support a causal link between current vaccines and the risk of MS or other CNS ADS,” the researchers wrote. “Our findings do not warrant any change in vaccine policy.”
Disclosure: See the study for a full list of relevant financial disclosures.