Anyone who’s ever suffered the coughs, chills, and sore muscles caused by influenza, or the flu, knows how unpleasant it can be—and to thousands of people with compromised immune systems, it can be deadly. That’s why the government provides flu vaccinations each year, starting in the autumn, to help prevent the spread of influenza to the people who are most at risk.

Because the influenza virus is constantly mutating, however, scientists must tweak the vaccine every year. They use inactive (dead) viruses to produce flu vaccine, so while people won’t actually catch the flu from a vaccination, they may experience flu-like symptoms. Each vaccine contains two influenza A viruses and one influenza B virus to protect against the various strains that scientists predict will be circulating during the coming months.

Because children and elderly people have weaker immune systems than healthy adults, the government recommends that everyone under age 18 or more than 50 get a flu vaccination annually. (However, babies younger than 6 months should not receive a flu vaccine.) People with chronic illnesses should be vaccinated too, as should anyone who is in close contact with these groups, such as doctors and nurses.

The flu vaccine is typically given as an injection or a nasal spray. Both types of vaccines are generally given at the beginning of flu season, in October or early November, and are available into the new year.

People who are vaccinated should not get the flu, or at worst should get a much milder version. Protection starts approximately 2 weeks after receiving the vaccine, although studies on the effectiveness of flu shots—especially among children and the elderly—have been mixed. Some research has suggested that doing physical activities, such as practicing qigong (a Chinese blend of exercise and meditation) or lifting weights, before a flu inoculation may increase the shot’s effectiveness.

ADDITIONAL FACTS

  1. Mercury-free vaccines are recommended for children under 2 years old and women who expect to be past the third month of pregnancy during flu season.
  2. Although most people recover quickly from the flu, it has historically been one of history’s deadliest diseases. A flu pandemic that began in 1918 killed 25 million people across the world—more deaths than were suffered by all sides World War I, which concluded in the same year.
  3. Anyone who has had a severe allergic reaction to chickens or egg protein should not have a flu shot.