(RxWiki News) Even though vaccines prevent disease, some people worry about the risks of the vaccines themselves. Fortunately, one risk people may be concerned about has been discounted.
A recent study found that the risk of developing Guillain-Barré syndrome is no higher for those who receive any vaccines, than for those who don't.
In other words, getting the flu vaccine or any other vaccine may not increase a person's risk of getting Guillain-Barré syndrome, a nerve disorder.
This study was one of the largest of its kind looking at millions of individuals' medical records.
"Ask your MD about the CDC's recommendations for vaccines."
The study, led by Roger Baxter, MD, of the Kaiser Permanente Vaccine Study Center in Oakland, California, looked for any links between vaccines and Guillain-Barré syndrome.
Guillain-Barré syndrome is a nerve disorder in which the body's immune system inappropriately attacks the body's nervous system.
Individuals have reported developing Guillain-Barré syndrome after having received various vaccines.
However, an investigation of those cases revealed that the vaccine did not cause the disorder. Instead, the timing of the vaccine and development of the disorder in those cases were coincidence.
The exception to this was the 1976 H1N1 flu vaccine.
Researchers did find an association with Guillain-Barré syndrome and that vaccine, though the risk was very small.
For this study, the researchers looked at 11 years worth of data in Northern California to see if Guillain-Barré syndrome was linked to any other vaccine.
The researchers looked at the medical records of all individuals who were hospitalized for Guillain-Barré syndrome from 1995 to 2006 in the Kaiser Permanente Northern California system. This search turned up 415 individuals.
Then the researchers looked at how many of those individuals had been vaccinated in the previous six to ten weeks before symptoms of the nerve disorder appeared.
These odds of vaccination were compared to the odds of being vaccinated in the general population among those without Guillain-Barré syndrome.
Taking into account the total years that the study covered and all of the individuals over those years, the study looked at 30 million "person-years." That is, the researchers investigated the risk of the disease out of every 30 million people vaccinated in one year, or out of every 1 million people vaccinated over a 30-year time period.
For the flu vaccine, the tetanus-diphtheria vaccine (Td) and the pneumonia vaccine (23-valent pneumococcal polysaccharide), the researchers found no higher risk that individuals would develop Guillain-Barré syndrome following vaccinations.
When the researchers looked at the odds that those with and without Guillain-Barré syndrome had received a vaccination against any disease, they still found no association between the nerve disorder and any vaccine.
In fact, only 25 individuals who had developed Guillain-Barré syndrome had received a vaccine within the previous six weeks. No one had developed Guillain-Barré syndrome after having received childhood vaccines.
The researchers identified 18 individuals who developed Guillain-Barré syndrome within six weeks of receiving the trivalent flu vaccine, out of a total of 6,841,901 flu vaccines that were given in that time period.
However, 13 of those individuals had a respiratory or gastrointestinal illness known to be risk factors for Guillain-Barré syndrome.
"In this large retrospective study, we did not find evidence of an increased risk of Guillain-Barré syndrome following vaccinations of any kind, including influenza vaccination," the researchers wrote.
The study was published April 11 in the journal Clinical Infectious Diseases. The research was funded by a subcontract with America's Health Insurance Plans through the Centers for Disease Control and Prevention.
Two authors reported having received research grants in the past from Merck & Company, Pfizer, Sanofi-Pasteur, Novartis Vaccines, GlaxoSmithKline and Med-Immune. No other disclosures were reported.