H1N1 vaccine associated with small but significant risk of Guillain-Barre syndrome
Guillain-Barre syndrome (GBS) is usually characterized by rapidly developing motor weakness and areflexia (the absence of reflexes). "The disease is thought to be autoimmune and triggered by a stimulus of external origin. In 1976-1977, an unusually high rate of GBS was identified in the United States following the administration of inactivated 'swine' influenza A(H1N1) vaccines. In 2003, the Institute of Medicine (IOM) concluded that the evidence favored acceptance of a causal relationship between the 1976 swine influenza vaccines and GBS in adults. Studies of seasonal influenza vaccines administered in subsequent years have found small or no increased risk," according to background information in the article. "In a more recent assessment of epidemiologic studies on seasonal influenza vaccines, experimental studies in animals, and case reports in humans, the IOM Committee to Review Adverse Effects of Vaccines concluded that the evidence was inadequate to accept or reject a causal relationship."
Philippe De Wals, M.D., Ph.D., of Laval University, Quebec City, Canada and colleagues conducted a study to assess the risk of GBS following pandemic influenza vaccine administration. In fall 2009 in Quebec an immunization campaign was launched against the 2009 influenza A(H1N1) pandemic strain. By the end of the year, 4.4 million residents had been vaccinated. The study included follow-up over the 6-month period of October 2009 through March 2010 for suspected and confirmed GBS cases reported by physicians, mostly neurologists, during active surveillance or identified in the provincial hospital summary discharge database. Immunization status was verified.
Over the 6-month period, 83 confirmed GBS cases were identified. Twenty-five confirmed cases had been vaccinated against 2009 influenza A(H1N1) 8 or fewer weeks before disease onset, with most (19/25) vaccinated 4 or fewer weeks before onset. Analysis of data indicated a small but significant risk of GBS following influenza A(H1N1) vaccination. The number of cases attributable to vaccination was approximately 2 per 1 million doses. The excess risk was observed only in persons 50 years of age or older.
"In Quebec, the individual risk of hospitalization following a documented influenza A(H1N1) infection was 1 per 2,500 and the risk of death was 1/73,000. The H1N1 vaccine was very effective in preventing infections and complications. It is likely that the benefits of immunization outweigh the risks," the authors write.
In an accompanying editorial, Mark C. Steinhoff, M.D., of the Cincinnati Children's Hospital Medical Center, and Noni E. MacDonald, M.D., M.Sc., F.R.C.P.C., of Dalhousie University, Halifax, Nova Scotia, Canada, write that "taken together, these studies partially assuage concerns about safety of adjuvanted pandemic influenza vaccines during pregnancy."
"However, more studies are needed examining other types of vaccine adjuvants. In addition, observational studies of vaccines are limited by biases, including selection bias, as well as confounding by indication. Thus, future studies with improved statistical designs including prospective follow-up studies using virological end points with adjustments for selection, seasonality, and other biases are needed to confirm these data."
More information: JAMA. 2012;308:175-181.
Journal reference: Journal of the American Medical Association
Provided by JAMA and Archives Journals
- Study: Guillain-Barre Syndrome cases low after 2009 H1N1 vaccine Apr 13, 2010 | not rated yet | 0
- No substantial link between swine flu vaccine and Guillain-Barre syndrome, confirm experts Jul 13, 2011 | not rated yet | 0
- Pandemic H1N1 influenza vaccine effective in 2009-10 flu season Jan 11, 2011 | not rated yet | 0
- WHO confirms swine flu vaccine child narcolepsy concerns Feb 08, 2011 | not rated yet | 0
- H1N1 influenza hits older children May 04, 2010 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Classical and Quantum Mechanics via Lie algebras
Apr 15, 2011 I'd like to open a discussion thread for version 2 of the draft of my book ''Classical and Quantum Mechanics via Lie algebras'', available online at http://lanl.arxiv.org/abs/0810.1019 , and for the...
- More from Physics Forums - Independent Research
More news stories
As the world prepares for what may be the next pandemic strain of influenza virus, in the H7N9 bird flu, a new UC Irvine study reveals that the 2009 H1N1 swine flu pandemic was deadliest for people under the age of 65, while ...
Diseases, Conditions, Syndromes 7 hours ago | not rated yet | 0
The World Health Organization says the Horn of Africa is experiencing an outbreak of polio with cases confirmed in Kenya and Somalia.
Diseases, Conditions, Syndromes 8 hours ago | not rated yet | 0
A man who had contracted the coronavirus has died in Saudi Arabia, raising the death toll in the kingdom from the SARS-like virus to 17, the health ministry announced on its website on Wednesday.
Diseases, Conditions, Syndromes 8 hours ago | not rated yet | 0
A new approach for immunizing against influenza elicited a more potent immune response and broader protection than the currently licensed seasonal influenza vaccines when tested in mice and ferrets. The vaccine ...
Diseases, Conditions, Syndromes 8 hours ago | not rated yet | 0 |
Patients with underlying heart failure are more likely to experience adverse outcomes from mild hypothyroidism, according to a recent study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & ...
Diseases, Conditions, Syndromes 10 hours ago | not rated yet | 0
Existing research shows that bicyclists who wear helmets have an 88 percent lower risk of brain injury, but researchers at Boston Children's Hospital found that simply having bicycle helmet laws in place showed a 20 percent ...
22 minutes ago | not rated yet | 0
Swiss scientists reveal the mechanism responsible for aging hidden deep within mitochondria—and dramatically slow it down in worms by administering antibiotics to the young.
11 hours ago | 4.9 / 5 (7) | 0 |
Researchers from Queen Mary, University of London have led the largest sequencing study of human disease to date, investigating the genetic basis of six autoimmune diseases.
11 hours ago | 4 / 5 (1) | 0 |
Until now, little was scientifically known about the human potential to cultivate compassion—the emotional state of caring for people who are suffering in a way that motivates altruistic behavior.
8 hours ago | 5 / 5 (2) | 2 |
(HealthDay)—Migraines and depression can each cause a great deal of suffering, but new research indicates the combination of the two may be linked to something else entirely—a smaller brain.
7 hours ago | 5 / 5 (1) | 0 |
Calorie information in fast food restaurants used by 40 percent of 9-18 year olds when making food choices
A new study published online today (Thursday) in the Journal of Public Health has found that of young people who visited fast food or chain restaurants in the U.S. in 2010, girls and youth who were obese were more likely ...
5 hours ago | not rated yet | 0