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Published on December 29, 2014

Early appearance, strain shift cause widespread flu in central Missouri

University of Missouri Health Care infectious diseases experts say increased numbers of influenza patients this fall are the result of an earlier flu season and a shift in the genetic makeup of one of the influenza strains.

In the United States, the annual flu season generally begins in late October, peaks sometime in January or February, and ends in early May.

“The difference this year is that we saw higher numbers in November and December as flu season was just getting started,” said Michael Cooperstock, M.D., medical director of MU Health Care’s Infection Control Department and a pediatric infectious disease specialist at MU Children’s Hospital. “We can expect to see another eight to 12 weeks of activity before the flu season ends.”

According to the Columbia/Boone County Department of Public Health and Human Services, the disparity between last year and this year is already quite large. On Dec. 28, 2013, the number of confirmed cases in Boone County totaled 85. The most current number available for 2014 is almost 1,100 confirmed cases.

Compounding the issue is the genetic shift in one of this year’s flu strains. Each year, manufacturers create vaccines that guard against the types of influenza experts predict are likely to be most common for the upcoming season. The quadrivalent vaccine offered this year guards against two forms of influenza A and two forms of influenza B viruses.

“This year, we had what is called a genetic drift in the influenza A H3N2 strain,” said Linda Johnson, R.N., manager of the Infection Control Department at MU Health Care. “This drift produced a strain that is not as genetically close to the type used in this year’s flu vaccine. The flu shot still offers protection against influenza, though it is not at the level we would like it to be.”

Johnson and Cooperstock both agree the vaccine still has plenty of value because it is still the best protection against influenza.

“It is not too late to get the flu shot,” Cooperstock said. “Even though the vaccine isn’t a perfect match, it still offers a good deal of protection. It will prevent the disease about 50 percent of the time. And for those who still get the flu, the severity of their symptoms and the duration of the disease will be reduced.”

To prevent the spread of influenza, Cooperstock suggests:

  • Cover your nose and mouth with a tissue when coughing or sneezing, and then throw the tissue away. If you do not have a tissue, cough or sneeze into your sleeve at the crook of your arm.
  • Wash your hands often with soap and water, especially after you cough or sneeze.
  • Use a hand sanitizer containing alcohol if you can’t wash your hands.
  • Avoid touching your eyes, mouth or nose, which are places where flu usually enters the body.
  • Avoid close contact with people who are ill.

“If you are sick, please stay home,” Johnson said. “Someone with influenza is considered contagious from the time their symptoms begin to at least 24 hours after they no longer have a fever. It is important that you don’t go out and share your flu with other people. Even if you are a young and healthy person, and your illness is something you think you can work through, this isn’t the case for everyone. Many people have underlying health issues, and sharing your influenza with them could be life-threatening.”

To receive a vaccination, please make an appointment with your primary care physician. If you do not have a primary care physician, please visit

For additional information about influenza, please visit