Each year, according to the Centers for Disease Control and Prevention (CDC), seasonal flu accounts for over 200,000 hospitalizations and 36,000 deaths in the United States. Getting a flu shot may reduce your chance of getting the flu by 70 to 90 percent and it may also reduce the severity of symptoms if you do get sick. However, in rare cases, the flu shot is associated with severe side effects you may wish to discuss with your health care provider.
Anaphylaxis
According to the flu shot maker, in less than 1 percent of cases the flu shot produces a life-threatening, system-wide allergic reaction called anaphylaxis. Anaphylaxis is most likely in people with allergies to eggs or certain kinds of antibiotics including kanamycin, gentamicin, neomycin and polymixin B. According to Medline Plus, anaphylaxis begins with symptoms like breathing problems, heart palpitations, skin reactions, slurred speech or mental confusion, and nausea, vomiting or abdominal pain. Without treatment, early symptoms progress rapidly to respiratory failure, cardiac arrest and coma.
Guillain-Barre Syndrome
Guillain-Barre syndrome (GBS) is an autoimmune disease in which the body makes antibodies against the sheaths that cover the peripheral nerves. According to the CDC, approximately 1 in 100,000 people who received the swine flu shot in 1976 and 2 per 1,000,000 people who received the seasonal flu shot between 1992 and 1994 developed GBS. GBS presents with premonitory symptoms of muscle weakness and tingling which, over the course of one to three weeks, develops into full-blown paralysis. Most people with GBS need to be put on a breathing machine or ventilator to prevent death from respiratory failure. Approximately 5 percent of people with GBS die despite supportive care. Among survivors, recovery is prolonged and nearly 1/3 report persistent weakness even after three years.
Arteritis
According to the makers of the Food and Drug Administration (FDA)-approved seasonal flu vaccine Afluria, arteritis or inflammation of the arteries has been reported in a small number of flu shot recipients. The first case of arteritis due to influenza vaccination was described in 2000, according to the authors of a 2002 article in, "Current Opinions in Neurology." The disease, which is also known as "temporal arteritis" or "cranial arteritis," presents with symptoms including new, severe headaches, visual disturbances, jaw and tongue pain associated with swallowing, and tenderness in the arteries across the forehead. In most cases, patients recover over the course of a few years, although most require prolonged courses of steroids.
Optic Neuritis
Optic Neuritis (ON) is a syndrome of eye pain and vision loss in one or both eyes. In a 2008 article in the "Journal of Clinical Neuroscience," the authors describe cases of ON which developed after a flu shot in 1996, 1997, 1998 and 2004. In the first case, the flu shot was not suspected as the cause until the disease recurred when the patient was re-vaccinated in 1997. Although each 2009-2010 flu vaccine manufacturer included neuritis among the possible side effects of the vaccine, ON is exceptionally rare and the role of the flu shot in causing ON is still not considered to be conclusively established.
Acute Disseminated Encephalmyelitis
Acute Disseminated Encephalomyelitis (ADE) is a rare, but severe side effect of several vaccines including flu, rabies, diptheria, and polio, among others. According to a 2008 study in the Journal of Clinical Neuroscience, ADE is more common in children than adults. The characteristic presentation of ADE is abrupt onset of fever, muscle weakness, increased or decreased reflexes, vision changes, impaired balance, loss of ability to read or write, inability to remember previously known words and other symptoms within at least three months of vaccine administration. Fever usually resolves within a few weeks, however neurological problems persist for months and even years. As with ON, ADE is extremely rare and firm evidence for the flu shot as its cause is lacking.
References
- Centers for Disease Control: Seasonal Flu Basics
- Current Opinions in Neurology; Neurological Adverse Events Associated with Vaccination; S. Piyasirisilp, T. Hemachudha; June 15 2002
- Journal of Clinical Neuroscience; Post-Vaccination Encephalomyelitis: Literature Review and Illustrative Case; W. Huynh, D.J. Cordato, E. Kehdi, L.T. Masters and C. Dedousis; 2008
