What Is A Flu Shot, How Does It Work And What Are The Side Effects?

Dr. James Conway answers the question: 'What Is A Flu Shot, How Does It Work?'

By
James Conway, M.D., Assoc. Professor of Pediatrics, Univ. of Wisconsin School of Medicine and Public Health
September 25, 2008, 10:02 AM ET
2 min read

— -- Question: What is a flu shot, how does it work and what are the side effects?

Answer: There are actually two different types of influenza vaccines. One is an injectable, inactivated vaccine and the other one is a nasal spray. Both of them basically act in the same manner. They both stimulate the immune system in a way that it thinks it's had an influenza infection before. So that when you come into contact with influenza viruses, your immune system is able to defend it and keep you from getting ill.

The side effects are actually quite mild. The injectable flu vaccine causes some local pain at the site of the injection and because the immune system is being a little stimulated, some people do have some mild aches and maybe a low grade fever. But you cannot get the actual disease influenza from the vaccine.

The nasal influenza vaccine is sprayed in the nose and some people have a little mild runny nose and sometimes a little scratchy throat, but really nothing more than that. And again those side effects are fairly mild and really well tolerated by most people.

Next: What Is A Nasal Spray Flu Vaccine (FluMist), How Does It Work And What Are The Side Effects?

Previous: Should Everyone Get A Flu Vaccine (Flu Shot)?

------

Get Your Questions Answered at the ABCNews.com OnCall+ Cold & Flu Center

  • Man Flu: A Man's Illness
  • Battle of the Nasal Washes: In One Nostril, Out the Other
  • Lost Your Voice? 5 Remedies Put to the Test
  • Six Soups to Soothe a Winter Cold