Preparing for the Flu Season

This illustration provides a 3D graphical representation of a generic influenza virions structure. (Photo credit: CDC/ Douglas Jordan)

This illustration provides a 3D graphical representation of a generic influenza virion’s structure. (Photo credit: CDC/ Douglas Jordan)

Tis the season for coughs, sneezes, sore throats, body aches, and high fevers. Are you ready for the flu season?

There are three kinds of flu viruses that affect humans. These include the influenza B viruses, influenza A (H1N1) viruses, and influenza A (H3N2) viruses. The flu vaccine is updated on a yearly basis so it can better combat which viruses are more prevalent the current flu season. The viruses chosen depend on a variety of information, including which flu viruses are being found in the population, the way in which the viruses are spreading, and how well the previous seasons vaccine might protect against newly-identified viruses.

While the World Health Organization (WHO) recommends which viruses should be included in that seasons vaccine, each country has the final say in the makeup of the vaccine distributed within its borders. In the United States, the Food and Drug Administration (FDA) has the final say as to which viruses will be included in flu vaccines licensed for use in the U.S. This year, the flu vaccine distributed in the U.S. is made up of these three viral components:

  • A/California/7/2009 (H1N1)pdm09-like virus
  • A/Victoria/361/2011 (H3N2)-like virus
  • B/Wisconsin/1/2010-like virus

If you examine the names of these viral components, you will recognize that they designate not only the kind of virus being combatted, but also the strain of that virus in a particular year and location. This emphasizes how adaptable flu viruses have become and the specificity required to combat them properly.

The Centers for Disease Control (CDC) recommends that everyone older than six months of age receive the flu vaccine each year. It is particularly important that those in high-risk populations (such as pregnant women, those older than 65, and those with medical conditions such as asthma, diabetes, or chronic lung disease) are vaccinated against the flu. People who care for or live with someone in a high-risk population should also get vaccinated. Because it takes up to two weeks for antibodies to develop in the body to provide protection against the flu, the flu vaccine is typically most effective if it is received before the onset of the flu season, which typically occurs during the late-fall and early-winter seasons.

Unlike other vaccinations, you need to receive a new flu vaccine each year as the bodys immunity to flu viruses declines over time. Also, influenza viruses are always evolving, and different strains appear from year to year. So, even if your body could remain immune to some strains of flu, it very well might not be immune to the new strains that might appear that season.

Even if you have been vaccinated, theres still a chance you will get the flu. What should you do if this occurs? The CDC recommends that those infected with the flu virus should stay home (aside from visits to the doctor) for at least 24 hours after the fever has disappeared. They should try to avoid contact with other people, cover their mouths when they sneeze or cough, and wash their hands often. A person that has the flu can spread the virus one day before getting sick themselves and up to seven days after the flu strikes.

More to Explore

Seasonal Influenza (flu)

Key Facts About Influenza and Flu Vaccine

World Health Organization – Global Influenza Programme

Busting Common Myths About the Flu Vaccine

Flu Trends


  1. Interesting. I did not realize that the vaccine is changed every year based on which viruses are anticipated to be a problem.

    Does regularly administering the vaccine contribute to the emergence of vaccine-resistant strains of the flu?

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