In its "Take 3 Actions to Fight the Flu" campaign, the U.S. Centers for Disease Control and Preventions (CDC) urges people to "take time to get a flu vaccine" as the first step toward reducing the risk of flu. In healthy adults, according to the CDC, the flu shot may reduce the risk of flu by 70 to 90 percent. There are complications, however, of flu shots you should be aware of.
Injection Site Reaction
Injection site reaction is a common complication of flu shots. In clinical studies by CSL Biotherapeutics for the FDA-approved vaccine Afluria, tenderness, pain, redness, swelling or bruising was reported in up to 60 percent of people within 4 days of receiving the vaccine. In 1 percent of people, symptoms were severe enough to interfere with activities. In rare cases, these symptoms were a harbinger of more severe complications include abscess and cellulitis. An abscess, according to Medline Plus, is a localized collection of pus while cellulitis is an infection of the skin. Both usually require antibiotics for resolution.
Guillain-Barre Syndrome
Guillain-Barre syndrome (GBS) is an autoimmune disease in which a person makes antibodies against sites on the peripheral nerves. Premonitory symptoms of GBS include weakness and tingling sensations in the legs. As the disease progresses, the arms, trunk and head are affected. In some cases, a person may become paralyzed for weeks or months. According to the CDC, GBS is fatal in 5 to 6 percent of cases. Among survivors, recovery often takes weeks or months. Nearly a third of patients report residual weakness 3 years later.
GBS was first linked to the flu shot in 1976, when one in 100,000 people who received the swine flu shot developed the disease. Between 1992 and 1994, the seasonal flu shot appeared to be associated with a 1.7-fold increase in the risk of GBS. Normally, says the CDC, about one in 1 million people develop the disease each year regardless of whether or not they have the flu shot. So the increase, which is controversial, amounted to less than one additional case per 1 million people. Currently, the CDC estimates that the risk of GBS associated with the flu shot is about one in 1 million.
Encephalomyelitis
According to a 2008 article in the "Journal of Clinical Neuroscience," acute disseminated encephalomyelitis (ADE) is a condition that has been linked to the flu shot and several other vaccines including polio, diptheria and rabies. ADE is characterized by diffuse inflammation of the brain and spinal cord which presents with the sudden onset of fever, muscle weakness, abnormal reflexes, vision loss or changes, loss of balance, loss of ability to read and write, forgetting previously known words and other symptoms. It has been described in both adults and children, although it is more common in children. In order to be considered vaccine-related, the onset of ADE must be within 3 months of receiving a vaccine. The disease is not permanent, but recovery often takes years. The cause of ADE has not been conclusively established, but is believed to involve an unusual interaction between a person's immune system and the vaccine.
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, D.J. Cordato, E. Kehdi, L.T. Masters and C. Dedousis; 2008
