In its "Take 3 Actions to Fight Flu" campaign, the Centers for Disease Control and Prevention (CDC) recommend immunization as the first step to reduce the risk of infection with seasonal and pandemic flu. In healthy adults, getting a flu shot can reduce a person's risk of getting the flu by 70 percent to 90 percent. However, in rare cases, the flu shot is associated with serious side effects.
Anaphylaxis
Anaphylaxis is a rare, life-threatening allergic reaction that onsets seconds to minutes after a flu shot. According to Medline Plus, a patient information service jointly operated by the National Library of Medicine and the National Institutes of Health, symptoms of anaphylaxis include breathing problems, irrregular heartbeat, skin reactions such as hives and altered mental status. The latter includes slurred speech and loss of consciousness. According to Food and Drug Administration (FDA)-approved flu vaccine manufacturers, it occurs in fewer than 1 percent of people who get the flu shot. People with allergies to eggs or certain kinds of antibiotics (gentamicin, kanamycin, neomycin and polymyxin B) or a history of flu shot-related anaphylaxis should not be vaccinated.
Guillain-Barre Syndrome
Guillain-Barre Syndrome (GBS), an autoimmune disorder in which the body makes antibodies against the peripheral nerves, was first linked to the flu shot in 1976 when approximately 1 in 100,000 people vaccinated for swine flu developed the disease. According to the CDC, GBS was again linked to the flu vaccine between 1992 and 1994 when 1 to 2 per million people who got the seasonal flu vacine developed the disease. The hallmark of GBS is ascending paralysis, which begins at the lower extremities and progressively affects the entire body, including the respiratory muscles. Approximately 5 percent to 6 percent of people afflicted with GBS die, despite supportive care. The disease takes several weeks to resolve, and residual weakness may be permanent.
Acute Disseminated Encephalomyelitis
Acute Disseminated Encephalomyelitis (ADE) has been linked to the flu shot, as well as other kinds of vaccines--including rabies, diptheria, polio and others. ADE presents with simultaneous 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. According to a 2008 study in the Journal of Clinical Neuroscience, symptoms usually appear within at least three months of receiving the vaccine and are more common in children than adults. The fever usually resolves quickly, but the neurological deficits may persist. Although ADE and vaccine administration are correlated, evidence of true causation is lacking.
Adverse Events
The Vaccine Adverse Event Reporting System (VAERS) is a national vaccine safety surveillance program jointly maintained by the CDC and the FDA. The purpose of VAERS is to collect information about adverse events that occur after vaccines are administered in order to identify possible side effects of the vaccines. In many cases, the events reported occur so infrequently that it is not possible to conclusively establish them as side effects of the vaccine. According to literature submitted by FDA-approved flu shot manufacturers, in addition to the side effects listed above, fewer than 1 percent of flu shot recipients experienced other possible, serious side effects that included temporary blood platelet deficiency, seizures, temporary blindness, paresthesia and kidney problems.
References
- CDC: CDC Says "Take 3" Actions to Fight the Flu
- FDA: Influenza Virus Vaccine for the 2009-2010 Season
- Journal of Clinical Neuroscience; Post-Vaccination Encephalomyelitis: Literature Review and Illustrative Case; W Huynh, DJ Cordato, E Kehdi, LT Masters, C Dedousis; 2008
