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TUESDAY, Oct. 21, 2014 (HealthDay News) -- A new study finds no link between vaccines and increased risk of multiple sclerosis or similar nervous system diseases.
Even though some have questioned whether vaccines -- particularly for hepatitis B and human papillomavirus (HPV) -- might be associated with a small rise in the risk of MS, prior studies yielded mixed findings on the issue, with most studies showing no link.
Many of those studies were limited by small numbers of participants and other factors, said the new team of researchers led by Dr. Annette Langer-Gould of Kaiser Permanente, Southern California, and colleagues.
In their new research, Langer-Gould's team analyzed data from 780 patients with MS or related diseases and compared their vaccination histories with that of more than 3,800 healthy patients. The participants included females aged 9 to 26, which is the indicated age range for HPV vaccination.
The researchers found no link between any vaccine -- including for hepatitis B and HPV -- and an increased risk of MS or related diseases for up to three years after vaccination, according to the study published online Oct. 20 in the journal JAMA Neurology.
Among patients younger than 50, there was an increased risk of the onset of MS and related diseases in the first 30 days after vaccination, but that association vanished after 30 days, the researchers found. That suggests that vaccination may accelerate the onset of symptoms in people who already have MS or related diseases but have not experienced any symptoms.
"Our data do not support a causal link between current vaccines and the risk of MS or [related diseases]. Our findings do not warrant any change in vaccine policy," the study authors wrote.
One expert in multiple sclerosis believes the study results are reassuring.
"While lingering questions about the safety of any vaccine continue to arise among the general public -- and especially among MS patients -- this well-executed study confirms what we already believe," said Dr. Karen Blitz, director of the North Shore-LIJ Multiple Sclerosis Center in East Meadow, N.Y.
"The only special consideration regarding vaccines that MS specialists recommend is that MS patients taking certain immunosuppressive drugs or disease-modifying therapies should stay away from vaccines containing 'live attenuated viruses,' such as the nasal mist vaccine for influenza," Blitz said.
-- Robert Preidt
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SOURCES: Karen Blitz, D.O., director, North Shore-LIJ Multiple Sclerosis Center, East Meadow, N.Y.; JAMA Neurology, news release, Oct. 20, 2014