Friday, January 4, 2013

Why Flu Spread So Fast In Those Schools

On December 10, 2012 the Health Department got a report from Shelly Millis, Superintendent of the Montebella Schools, that 180 children and teens were out sick with flu-like symptoms.  Some had tested positive for influenza types A and B. Our Medical Director, Dr. Robert Graham recommended that the schools close to halt the further spread of the illness. (This was a recommendation to the Superintendent who made the decision herself.  It was not a case of the Health Department ordering the school to close.)

Ten days later, on December 20th the same thing happened at Central Montcalm schools. With 259 students  out, Superintendent Kristi Teall made the decision to send everyone home. Coincidentally this was the same week some schools were dealing with gun rumors in the wake of Sandy Hook shootings.

Why did the flu spread so fast in these schools?  We used data from the Michigan Immunization Registry to examine the influenza immunization status of the students in the Montebella Schools.  Only 22 percent of the elementary age students had up-to-date flu shots, and only 4 percent of the middle and high school age students did. Four percent!

With so few students protected against the flu, it’s no wonder things got out of hand so fast.  Very few students had any level of immunity so the virus spread easily.  We are used to thinking of the decision to get a flu shot as an individual choice.  But getting a shot is a much about protecting others as it is about protecting ourselves. Everyone’s lives in those two schools were disrupted because they didn’t have “herd immunity”.

This is discouraging. The Health Department used to give thousands of flu shots every year, but now it is down to around 1,000 per year and falling fast. Now that so many pharmacies give flu shots, we hope people are going there to get their shots, but maybe that is not working as well as we hope it will.

By the way, the flu is here in earnest. In the graph below from the CDC, the red line is the percentage of people showing up at emergency rooms with flu-like symptoms. It is headed up fast meaning an early, and probably pretty intense flu season.

It’s not too late to get a flu shot. If you get one tomorrow it will kick in in about two weeks. But the flu season should last at least 10 more weeks so it should be worth it.

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