The flu vaccine is available as an intramuscular injection (flu shot) or a powder for oral inhalation. The Centers for Disease Control and Prevention (CDC) urges all Americans to get vaccinated as the first step toward protecting themselves from the flu. Even if the flu vaccine does not prevent you from getting the flu, it may, according to the CDC, reduce the severity of your symptoms and the likelihood of flu-related complications. However, the flu vaccine is associated with some dangers that you may want to consider.
Injection Site Complications
In clinical studies by the makers of Agriflu, 30 percent of people who received the flu shot reported mild-to-moderate muscle pain near the injection site during the first four days after vaccination. In one percent of patients, this pain was so severe that it interfered with daily activities. In very rare cases, injection site infections requiring antibiotic treatment have been described. The inhaled vaccine is not associated with this kind of complication.
Flu-Like Illness
In another study by the makers of Agriflu, nearly 25 percent of adults who received Agriflu or a competitor vaccine, Fluvirin, complained of systemic symptoms resembling flu, such as headache (22 percent), generalized muscle pain (19 percent), malaise (12 percent), fatigue (9 percent), chills (8 percent), joint pain (6 percent), sweating (4 percent) and fever higher than 101.3 degrees F (3 percent). In most cases, symptoms occurred within the first four days after the shot was given. Children experience more diverse symptoms, including irritability, runny nose, cough, loss of appetite, vomiting, diarrhea and sore throat.
Anaphylaxis
In rare cases, the flu shot can cause a severe, life-threatening allergic reaction known as anaphylaxis. According to the American College of Allergy, Asthma & Immunology, symptoms of anaphylaxis include trouble breathing, hives, tightness of the throat, hoarse voice, nausea, vomiting, abdominal pain, diarrhea, dizziness, low blood pressure, rapid heartbeat and a feeling of doom. Although the first symptoms may simply consist of a "strange feeling," they can quickly progress to cardiac arrest and death. People with allergies to eggs and certain kinds of antibiotics should consult their healthcare providers prior to receiving the flu vaccine.
Guillain-Barré Syndrome
Guillain-Barré syndrome (GBS) is an autoimmune disease affecting the peripheral nerves. One in 100,000 people who received the swine flu vaccine in 1976 and one to two in 1 million people who received the seasonal flu shot between 1992 and 1994 developed GBS. Early symptoms of GBS include muscle weakness and tingling, which develops into paralysis. A defining feature of GBS is ascending paralysis, which begins in the lower extremities and progressively affects the upper extremities, face and trunk. According to the CDC, between five and six percent of people with GBS die despite supportive care. Among those who survive, recovery is prolonged.
Encephalomyelitis
Acute disseminated encephalomyelitis (ADE) has been linked to the flu shot as well as vaccines for other diseases, including rabies, polio and diphtheria. According to a 2008 article and case report in the "Journal of Clinical Neuroscience," ADE is more common in children and characteristically onsets within three months of vaccination. Symptoms usually develop suddenly, including fever, muscle weakness, increased or decreased reflexes, vision changes, impaired balance, loss of ability to read or write and the inability to remember previously known words. Although the fever resolves within days to weeks, neurological deficits usually persist for months or years. The cause of ADE has not been conclusively established, but it probably involves an interaction between the flu shot and a person's immune system.
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
