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Since mid-November, 44 grade-schoolers have developed the pox. All but two were vaccinated. The outbreak began at the Kindernook Learning Center — where 36 of 99 kindergarteners developed the virus — and it spread to siblings in other buildings.
The Wisconsin Department of Health and Family Services is trying to find out why so many vaccinated students developed chickenpox, when health experts rate the vaccine from 85 to 97 percent effective.
“We’re way above the 15 percent,” G-E-T school nurse Barbara Hogden said.
Dan Hopfensperger, director of the Wisconsin Immunization Program, said this is the state’s largest outbreak he can recall among vaccinated children.
The only other similar case occurred at a Dane County school in 2003, where slightly fewer students were affected. Hopfensperger said the state never determined a cause there.
So far there’s no apparent cause of the large number of G-E-T “breakthroughs” — term for a vaccinated person who still develops chickenpox.
Hogden said the vaccine is fragile and must be stored frozen. She said the infected students obtained vaccinations from a number of different providers.
Hopfensperger said there have been no reportsof a bad batch of vaccines from the manufacturer.
Only one case of the chickenpox at G-E-T cannot be traced back to the kindergarten building, Hogden said, and that student was not vaccinated.
Wisconsin began requiring all kindergarteners be immunized for chickenpox in 2001. This was the first year all schoolchildren had to be vaccinated or have had the virus unless a parent requested an exemption based on health reasons or personal convictions.
The number of reported cases has fallen in Wisconsin from 5,157 in 1996 to 487 in 2005.
Minnesota requires four grades of students to be immunized but will expect all students to be in compliance by 2010, unless they have an exemption.
Winona Area Public Schools head nurse Mitzi Girtler said she isn’t aware of any students who’ve developed chickenpox in the district this school year.
Why be immunized?
The chickenpox vaccine is the best way to prevent chickenpox and almost always prevents severe complications and death associated with the disease.
How effective is the chickenpox vaccine?
About 8 to 9 out of every 10 people who are vaccinated are completely protected from chickenpox. If a vaccinated person does get chickenpox, it is usually a very mild case with fewer skin lesions (usually less than 50) lasting only a few days, no fever or a low fever, and few other symptoms.
Source: Information from the Centers for Disease Control and Prevention.
Reporter Shannon Fiecke can be reached at (507) 453-3519 or shannon.fiecke@winondailynews.com.
