Influenza ("the flu") is a contagious disease with symptoms such as fever, chills, cough, fatigue, and muscle pain. Flu vaccines protect against flu infection, and are formulated yearly to provide protection despite seasonal changes in the virus. According to the Centers for Disease Control (CDC), two types of flu vaccine are available: the flu shot and the nasal spray flu vaccine. The nasal-spray flu vaccine is made by the pharmaceutical company MedImmune and provides effective protection against the flu.
Asthma
MedImmune conducted a clinical trial to compare side effects experienced by people given the nasal spray vaccine FluMist or a flu shot. When considering the effects on children ages 1 to 17 years of age, children under 5 years were at a slightly increased risk for experiencing asthma-related symptoms. According to the clinical trial data, 4.2 percent of children given FluMist, compared with 3.2 percent of those given the flu shot, experienced wheezing and were hospitalized (though the reason for hospitalization was not necessarily asthma-related). Thus, FluMist vaccination carries with it a slightly increased risk of asthma-related complications when compared to the flu shot.
Flu-Like Symptoms
Children vaccinated with FluMist sometimes experienced symptoms similar to that of the flu itself. According to the clinical trial data, 51 to 58 percent of children between the ages of 2 and 6 years experienced nasal congestion and a runny nose 10 days after vaccination with FluMist. This is compared with an incidence of 50 percent of children 2 to 6 years old given a placebo nasal spray and 42 percent given the flu shot. These data indicate that the injection of other FluMist ingredients, whether intranasally or by shot, cause these mild though frequent nasal symptoms.
Other symptoms of the flu experienced by FluMist vaccinated children were decreased appetite (4 percent), irritability (2 percent), fatigue (3 percent), sore throat (2 percent), headache (2 percent), muscle aches, fever (1 to 3 percent) and chills (1 percent). The percentage following the symptom indicates the increase in incidence between side effects from the placebo versus FluMist. Similar results were seen in adults.
Anaphylaxis
Very rarely, people vaccinated with either FluMist or the flu shot experienced a severe systemic allergic reaction (anaphylaxis) requiring medical attention. The FluMist vaccine contains a weakened virus grown in eggs, and some egg proteins still remain in the final form of the vaccine. Thus, people allergic to eggs may experience a severe allergic reaction in response to FluMist, as well as to many other vaccines. Other components of the vaccine that may cause an allergic reaction are gentamicin, gelatin and arginine.
