The influenza virus, commonly referred to simply as the flu, causes thousands of deaths every year, according to the U.S. National Library of Medicine's Medline Plus Medical Encyclopedia. Flu shots are an injectable form of vaccine designed to protect people from contracting the potentially deadly virus.
Description
A flu shot is made from inactivated flu virus, which means that it contains viruses that have been killed. The viruses are grown using chicken eggs, and then inactivated and purified before being made into vaccines. Adults get one shot, while children under nine need two doses one month apart to confer immunity. The shot is given in the arm and the body responds to the vaccination by producing antibodies against the flu virus. These antibodies will recognize and destroy any future incursion of the flu virus into the body.
Viral Strain
Because the strain of flu called influenza A mutates quickly, different variants of the flu appear each year, each needing a different vaccine to protect against it. Scientists use epidemiological data and lab tests on current flu strains to try and predict which types will be prevalent in a given flu season, which begins in late October or early November and lasts until April. They choose three strains each year to include in the vaccine, explains the Centers for Disease Control (CDC). The vaccine is made available to the public early in the flu season.
Recommendations
The CDC recommends that certain people get the seasonal flu vaccine every year: pregnant women, children from six months to 19 years of age, individuals older than 50, anyone with chronic medical conditions, individuals living in nursing homes and people who care for anyone who's at high risk for complications if they contract the flu.
Warning
Some people should not get a flu shot. These include anyone allergic to chicken eggs and anyone who has had a bad reaction to a flu shot before. Individuals who have developed the autoimmune disease Guillain-Barre syndrome after having a flu shot in the past should also avoid future vaccinations. People who are currently ill with a fever should wait until they are well to have a flu shot.
Effects
The flu vaccine takes full effect about two weeks after the shot is given. According to KidsHealth.org, the flu virus is 80 percent effective in a given flu season. It is less effective in adults over age 65, since their bodies produce fewer antibodies overall. Most people don't notice any side effects, and those who do report only mild issues. Headache and a low fever are two side effects that do occur occasionally.
