It has been a long debate in the United States as to whether or not vaccines used to battle the H1N1 outbreaks of recent lead to the development of Guillain-Barre syndrome, a rare disorder that causes the body's immune system to turn against itself, resulting in muscle weakness and even paralysis. A new study says no such chance.
In 1976, a vaccine used during a U.S. flu outbreak was linked to the disease, and the government halted vaccination, but in a study published July 13 in the British Medical Journal, a renowned group of researchers reported that the H1N1 vaccine posed little, if any, increased risk for the disease.
The researchers state:
"This study provides reassurance that adjuvanted pandemic influenza A (H1N1) 2009 vaccines did not increase the risk of Guillain-Barre syndrome substantially, if at all."
Guillain-Barré syndrome is a disorder in which the body's immune system attacks part of the peripheral nervous system. The first symptoms of this disorder include varying degrees of weakness or tingling sensations in the legs. In many instances, the weakness and abnormal sensations spread to the arms and upper body. These symptoms can increase in intensity until the muscles cannot be used at all and the patient is almost totally paralyzed. In these cases, the disorder is life-threatening and is considered a medical emergency.
The patient is often put on a ventilator to assist with breathing. Most patients, however, recover from even the most severe cases of Guillain-Barré syndrome GBS), although some continue to have some degree of weakness.
Usually Guillain-Barré occurs a few days or weeks after the patient has had symptoms of a respiratory or gastrointestinal viral infection. Occasionally, surgery will trigger the syndrome. In rare instances, vaccinations may increase the risk of GBS. The disorder can develop over the course of hours or days, or it may take up to 3 to 4 weeks.
No one yet knows why Guillain-Barré strikes some people and not others or what sets the disease in motion. What scientists do know is that the body's immune system begins to attack the body itself, causing what is known as an autoimmune disease.
The research was spawned from an analysis of 50 million people in five European countries that vaccinated people against H1N1 in 2009. The researchers compared 104 people with Guillain-Barre syndrome or a related condition to other people without the diseases.
The researchers adjusted their statistics to account for other risk factors for the diseases and found no link between flu vaccination and Guillain-Barre syndrome. Still, noting that it's possible a small risk might remain, they estimated there may be less than three extra cases of Guillain-Barre syndrome for each one million people who get protected by a flu vaccination.
Larger studies already in progress should provide even more definitive information, the study authors added.
The flu is a serious disease, and while most cases are mild, some can be deadly. So far this flu season, most flu activity has been caused by the 2009 H1N1 virus, which was first identified in April 2009 and caused the first flu pandemic in 40 years.
Because many people with influenza illness are not tested for flu or are tested late in their illness, methods have been developed to estimate the numbers of people with influenza illness and with influenza-related complications, including hospitalizations and deaths. CDC estimates that from April to January 16, 2010, approximately 57 million cases of 2009 H1N1 occurred in the United States, including 257,000 H1N1-related hospitalizations and about 11,690 deaths.
Sources: The British Medical Journal and The U.S. Centers for Disease Control and Prevention
Written by Sy Kraft