Chicago Flu Outbreak Proves It's Not Too Late to Get Vaccinated

So far, this has been a mild flu season in the Chicago area but beware – the area is not completely out of the woods yet. A Catholic school on Chicago's Southwest Side discovered that when more than 200 of its 700 students plus several teachers called in sick because of an outbreak of the flu this month.

"In a closed environment with runny noses and coughs and sneezes...viruses of all kinds can travel pretty easily," said Dr. Anita Varkey, assistant professor of general internal medicine at Loyola University Chicago Stritch School of Medicine in Maywood, Ill.

Flu activity can occur as late as May, and in any single season more than one strain of influenza may circulate, according to the Centers for Disease Control and Prevention (CDC). Fortunately, this year's vaccine has been a good match to the virus strains that are circulating in the United States. So getting a vaccine this late in the season can still offer protection, even if flu activity has already started in your area.

"Doctors used to advise getting a flu shot only in October and November. Now doctors vaccinate through February because it takes about two weeks to develop an antibody response after the flu shot," said Dr. Michael Koller, associate professor at the Stritch School of Medicine. "For the last 30 years in the United States, February has been the peak month for illness."

The flu is a highly contagious viral infection that attacks the respiratory system. Each year in the U.S. between five to 20 percent of the population contracts the flu. All children age 6 months to 18 years should get vaccinated against the flu. The CDC also recommends vaccinations for people age 50 and older and anyone with a chronic illness such as asthma, diabetes or heart disease. This includes people who have weakened immune systems and those infected with HIV.

"Flu is primarily spread by respiratory droplets," Koller said. "When somebody with influenza coughs or sneezes, out shoots this spray of flu virus that can infect anyone nearby. In addition to covering your mouth when you cough and covering your nose when you sneeze, it's really important to wash your hands."