In its "Take 3 Actions to Fight the Flu" campaign, the Centers for Disease Control and Prevention (CDC) urges people to "take time to get a flu vaccine" as the first step toward reducing the risk of flu. In healthy adults, the flu shot may reduce the risk of contracting the flu by 70 to 90 percent, but there are also potential side effects associated with flu shots that should be considered.
Injection Site Reactions
In clinical studies by CSL Limited for the FDA-approved vaccine Afluria, the most common injection site reactions were tenderness (60 percent), pain (40 percent), redness (16 percent), swelling (9 percent) and bruising (5 percent). In most cases, symptoms resolved within 2 days. In 1 percent of people, symptoms were severe enough to interfere with their daily activities. In very rare cases, these symptoms led to other complications, including abscess and cellulitis.
Flu-Like Illness
In clinical studies by GlaxoSmithKline for the FDA-approved flu shot Flulaval, the most common flu-like symptoms were headache (18 percent), fatigue (17 percent), muscle pain (13 percent), fever (11 percent), malaise (10 percent), sore throat (9 percent), eye redness (6 percent), cough (6 percent) and chills (5 percent). Compared to the flu, flu-like illness after the flu shot is mild and short-lived, usually resolving within 2 days. More symptoms are reported in children, including irritability, nasal irritation, loss of appetite, vomiting and diarrhea.
Guillain-Barre Syndrome
Guillain-Barre (ghee-YAN bah-RAY) syndrome (GBS) is an autoimmune disease in which a person makes antibodies against their own peripheral nerves. Early symptoms of GBS include weakness and tingling sensations in the legs. As the disease progresses, the arms, trunk and head may become involved. In some cases, a person may be 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. Approximately 30 percent of patients still report persistent weakness after 3 years.
GBS was first linked to the flu shot in 1976, when 1 in 100,000 people who received the swine flu shot developed the disease. From 1992 to 1994, the seasonal flu shot also appeared to be associated with a 1.7-fold increase in the risk of GBS. Normally, according to the CDC, only 1 in 1,000,000 people develop the disease each year whether or not they receive the flu shot. Thus, the increase, which is controversial, amounted to less than 1 additional case per 1,000,000 people. Currently, the CDC estimates that the risk of GBS associated with the flu shot is about one in one million.
