According to the Centers for Disease Control and Prevention (CDC), the flu vaccine is effective in 70 to 90 percent of healthy adults under 65 years of age, providing that the flu strain matches the flu shot composition. The vaccine administered in the flu shot changes each year based on the expected viruses of the season. As the vaccine for the flu shot is grown in eggs, it should not be provided to people with severe chicken egg allergies.
Soreness
According to the CDC, the most common side effect of the flu shot is soreness at the place where the shot was provided. This can be a result of the body working to make antibodies that will help protect it against getting the flu. Likewise, redness or swelling may appear. This usually goes away within two days.
Fever
According to MedlinePlus, a fever does not indicate sickness or illness but is part of the body's defense system to protect against infection. According to the CDC, some people may get a low-grade fever after receiving the flu shot. This usually lasts for a day or two. A fever can be helpful and serve as the body's way of recognizing the vaccine.
Aches
According to MedlinePlus, body aches can result from receiving the flu shot. These can occur from the body working to produce the necessary antibodies to prevent contracting the flu. These minor aches may be present for one or two days after receiving the flu shot.
Guillian-Barre Syndrome
According to the CDC, Guillian-Barre syndrome (GBS) is a disorder where the blood damages its own cells and results in muscle weakness and possible paralysis. Those developing GBS within six weeks of receiving a flu shot in the past should not be vaccinated. This is a very rare side effect and, according to MedlinePlus, the flu shot has shown no association with this disorder in children since 1976 and an extremely small rate of increases in adults.
Nasal Flu Spray Vaccine Side Effects
The nasal flu spray vaccine is different from the flu shot vaccine. It is made from live, weakened flu virus instead of the killed virus in the flu shot. According to MedlinePlus, it is can be used as a substitute for the flu shot in healthy people between the ages of 2 and 49. Common side effects can include fever, headache, runny nose, vomiting and some wheezing.
