History

• Shots are the most common vaccination method.Image by Flickr.com, courtesy of El Alvi
  
  Scientists discovered flu vaccinations in the 1930s, and developed them for use during World War II. Concerns first swirled in 1976, when hundreds of people vaccinated against swine flu developed nerve damage, and paralysis, symptoms associated with Guillain-Barré Syndrome.
  
  

Effects

• Following the 1976 incidents, the Centers for Disease Control and Prevention recommends that people with histories of Guillain-Barré Syndrome consult a doctor before getting vaccinated.
  
  

Features

• A doctor prepares for giving out vaccinations.Image by Flickr.com, courtesy of Vita
  
  Persons with allergies, especially those who have shown a reaction against eggs, are also advised to consult a doctor before getting their shot, according to the centers' website, www.cdc.gov. Signs may include dizziness, fast heartbeats, hives, and hoarseness or wheezing.
  
  

Significance

• Critics also point to the makeup of flu shots, which may include additives like formaldehyde, gelatin and mercury. Some immunologists have linked the latter substance to higher rates of Alzheimer's Disease, a disease that affects memory and concentration.
  
  

Nasal Sprays

• Intravenous nasal sprays are associated with flu-like side effects, such as coughing, chills, headaches, irritability and muscle aches. FluMist, a variation approved in 2003, has also been linked to a higher risk for Bell's Palsy.
  
  

Considerations

• The influenza virus's ever-changing nature also requires changes in vaccines, which sometimes results in unintended consequences. In 2004, regulators scrapped 48 million doses after finding them tainted with bacteria, Time magazine reported.