According to the Centers for Disease Control and Prevention (CDC) in 2008, seasonal flu results in more than 200,000 hospitalizations and 36,000 deaths each year. Getting a yearly seasonal flu vaccine, the CDC says, is the first and most important step in protecting yourself and others against seasonal influenza. Vaccination also offers other benefits.
Decreased Risk of Flu
According to the CDC, the seasonal flu vaccine can reduce the risk of getting influenza by 70 to 90 percent in healthy adults. The nasal spray flu vaccine is approved only for healthy people from ages 2 to 49 who are not pregnant--limitations that exclude infants, the elderly, pregnant women and people with medical problems--virtually all of the groups the CDC designates as "high risk" for complications of flu. By contrast, the flu shot can be given to almost anyone over six months of age.
Decreased Risk of Complications
The flu shot doesn't prevent all cases of influenza for two reasons. According to a Sept. 12, 2008 article in "Vaccine," the flu virus is constantly changing. The strains in the flu vaccine are selected more than six months before the beginning of the flu season. By the time the flu season begins, the circulating flu strains may have changed. Also, some people don't respond to the vaccine or respond incompletely. However, in both cases, seasonal flu vaccination still reduces the risk of severe illness and complications that require hospitalization through a process the CDC calls "cross-protection." Cross-protection means that people who receive the flu shot make some antibodies, which, even if they aren't completely effective at preventing the disease, still decrease its severity and help people recover faster.
Herd Effect
The people at highest risk for severe illness due to influenza are also those who often have a poor response to the flu shot. However, vaccination of other healthy people helps protect these people, too. This is called the "herd effect." It works because fewer infected people means fewer people who can spread the disease. Accordingly, the CDC's Advisory Committee on Immunization Practices specifically recommends that people who live with or care for those at high risk for serious seasonal flu-related complications get vaccinated each year, even though they may not be at high risk themselves.
References
- CDC: Seasonal Flu Vaccine Questions & Answers
- "Vaccine;" The Biology of Influenza Viruses; N.M. Bouvier and P. Palese; Sept. 12, 2008
- CDC: Influenza Vaccination - A Summary for Clinicians
