Vaccines do not cause MS, other demyelinating diseases

Last Updated: 2014-10-20

By Will Boggs MD

NEW YORK (Reuters Health) - Vaccines do not appear to cause multiple sclerosis or other central nervous system (CNS) demyelinating syndromes, but they may accelerate the transition from subclinical to overt disease, according to results from a nested case-control study.

"Our key takeaway message for clinicians is that our anecdotal experiences of first onset of MS symptoms shortly after vaccination do not mean that the vaccination caused the individual to develop MS," Dr. Annette Langer-Gould from Kaiser Permanente, Southern California, Pasadena, California told Reuters Health by email. "Our epidemiological study was able to detect a short term increased risk but only in younger individuals and only for the first 30 days after vaccination."

Some earlier studies have suggested an association between hepatitis B vaccine or human papillomavirus (HPV) vaccine, with an increased risk of multiple sclerosis (MS) or acquired CNS demyelinating syndromes (ADS), but the associations remain controversial.

Dr. Langer-Gould and colleagues used data from the Kaiser Permanente Immunization Tracking System to examine in more detail the association between the first onset of CNS demyelinating syndromes and vaccines.

As reported October 20th online in JAMA Neurology, their study included 780 patients with newly diagnosed MS, clinically isolated syndrome (CIS), or acute disseminated encephalomyelitis (ADEM).

There were no cases of ADS or ADEM within 42 days or one year of any hepatitis B-containing vaccination and no association of new-onset MS or CIS in the one to three years after vaccination with any hepatitis B-containing vaccination.

There was a nonsignificant trend toward an increased risk of MS (but not CIS or ADEM) within the first three months after HPV vaccination.

Similarly, there was no association between any vaccination three years earlier and CNS ADS, although the risk of CNS ADS was increased 30 days after any type of vaccination in individuals under age 50.

"However," the researchers say, "this association disappeared after 30 days, suggesting that, at most, vaccines are redundant enhancers of preexisting autoimmunity."

For individuals over age 50, there was no association between any vaccination and CNS ADS during any time interval.

Among the 11 individuals who developed their first symptoms of MS within 30 days following vaccination, all made a full recovery from their first attack. Moreover, nine of 12 patients with optic neuritis or idiopathic transverse myelitis within 30 days after vaccination had no asymptomatic lesions identified on brain MRI.

"We were certainly surprised to detect a temporal relationship in younger individuals two to four weeks after vaccination, although in retrospect it makes sense, as this is what clinicians have been reporting for many years," Dr. Langer-Gould said.

"The short-term increase in risk suggests that vaccines may accelerate the transition from subclinical to overt autoimmunity in patients with existing disease," the researchers say.

"The important thing for these individuals to know is that if they develop neurological symptoms that are continuous and last more than 24 hours, they should seek medical care and request to be evaluated by a neurologist, as multiple sclerosis is often a difficult diagnosis for non-neurologists to make," Dr. Langer-Gould advised.

She added, "Answering the question of vaccine safety and the risk of MS is difficult and requires large numbers of individuals, carefully collected clinical information, and many studies. For newer vaccines like HPV that only recently started to be given to boys, we and other researchers need to continue to gather and share data."

Dr. Jorge Correale from Raul Carrea Institute for Neurological Research, Foundation for the Fight against Infant Neurological Illnesses, Buenos Aires, Argentina has published widely on multiple sclerosis. He told Reuters Health by email, "These data are in agreement with our previous review and meta-analysis conducted in our Center by Dr. Mauricio Farez."

"Years ago a French report communicated that hepatitis B vaccination can induce MS," he noted. "However, no other series reproduced these findings, and today the MS community assumes that this vaccine does not increase the risk of MS. This was also reported in our previous communication."

Dr. Correale added, "We report some few, but serious, cases of exacerbation of MS after vaccination with yellow fever vaccine. Therefore, we do not recommend to use this vaccine in patients with an established diagnosis of MS, and of course, we discussed in depth with the patient risk versus benefits of vaccine if he/she must travel to an endemic area."

SOURCE: http://bit.ly/1wkkT7F

JAMA Neurol 2014.