In its "Take 3 Actions to Fight the Flu" campaign, the Centers for Disease Control and Preventions (CDC) lists "take time to get a flu vaccine" as the No. 1 thing people can do to reduce their risk of getting the flu. In healthy adults, the flu shot may reduce the risk of flu by 70 to 90 percent. However, educated consumers often ask, "What are the risks of having a flu shot?"
Allergic Reactions
The FDA required all 2009-2010 flu shot manufacturers to include the risk of allergic reactions in their prescribing information. Although most allergic reactions are mild, in rare cases, administration of the flu shot has been linked to serious, even life-threatening allergic reactions including serum sickness and anaphylaxis. According to Medline Plus, serum sickness usually develops one to three weeks after exposure to the flu shot or other triggers. Symptoms include fever, feeling sick, hives, itching, joint pain, rash, swollen lymph nodes and swelling of the arms, legs and face. In some cases, serum sickness can progress to anaphylaxis. Swelling is also serious on its own when it affects the throat and interferes with breathing. Anaphylaxis is a medical emergency that can also develop within seconds or minutes of exposure to the flu shot or other allergens, according to Medline Plus. Symptoms of anaphylaxis include trouble breathing, hives or skin rashes, hoarseness, tightness in the throat, vomiting, diarrhea, abdominal pain, low blood pressure, a sense of doom and cardiac arrest. People with allergies to eggs, antibiotics, natural rubber, latex or a history of previous life-threatening allergic reaction to the flu shot should share this information with their health-care provider before being vaccinated.
Guillain-Barre Syndrome
Guillain-Barre, pronounced ghee-YAN bah-RAY, syndrome (GBS) is a disease in which a person makes antibodies against their own nerves. According to the CDC, GBS can last for weeks or months and sometimes causes death. Approximately one in 1 million people in the United States develop GBS each year. In 1976, one in 100,000 people who were vaccinated for the swine flu also developed GBS. Then, between 1992 and 1994, the risk of developing GBS among people vaccinated for seasonal flu was 1.7 times that of people who were not vaccinated; however, the significance of this is controversial because it amounts to less than one extra case per million people vaccinated. The hallmark of GBS is ascending paralysis that begins in the legs and spreads to the trunk and arms.
Neuritis
Optic neuritis (ON) is a condition in which the optic nerve becomes inflamed. Symptoms include severe pain and vision loss in one or both eyes. ON is not permanent; however, recovery may be prolonged. According to a 2008 article in the Journal of Clinical Neuroscience, cases of ON following the flu shot were reported in 1996, 1997, 1998 and 2004. The relationship between ON and the flu shot was not suspected until a1996 patient experienced a recurrence upon re-vaccination in 1997. Since then, a handful of other cases have been reported.
Encephalomyelitis
Acute disseminated encephalomyelitis (ADE) is a condition in which the brain and spinal cord are diffusely inflamed. ADE begins 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. According to a 2008 article in the Journal of Clinical Neuroscience, ADE has been described in both adults and children who received the flu and other kinds of shots including polio, diptheria, rabies and others. In order to be considered vaccine-related, the onset of ADE must be within three months of receiving a vaccine. Although the disease is not permanent, recovery often takes years.
Arteritis
The flu shot has been linked to a kind of inflammation of the arteries known variously as "temporal arteritis," "giant cell arteritis" and "cranial nerve arteritis." According to a 2002 article in Current Opinions in Neurology, the first case was described in 2000 when a patient presented with symptoms including new, severe headaches, visual disturbances, jaw and tongue pain associated with swallowing, and tenderness in the visible arteries across the forehead. In some cases, temporal arteritis has lead to other complications such as stroke. In most cases, the condition is not permanent, although patients may require prolonged treatment with steroids.
References
- 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
- Current Opinions in Neurology; Neurological Adverse Events Associated With Vaccination; S Piyasirisilp, T Hemachudha; June 15, 2002
