Given the task definition and input, reply with output. Generate an explanation for the given claim using the provided supporting material from the paragraph. Please consider the following points while generating an output. 1) The claim will always have supporting proof in the paragraph, and the paragraph will have a clear point of view supporting the claim. 2) There can be instances where direct correlation to the claim is not available. Make use of the sentences in the paragraph to provide a corresponding output supporting the claim. 3) The explanation should be at least one and at most twelve sentences long.

Paragraph: The Journal Sentinel says figures from the Centers for Disease Control and Prevention show 1,215 cases of measles this year across the nation, the highest number since 1992. Wisconsin health officials have investigated 382 suspected measles cases since last November and not one case has been confirmed. Immunization rates of 92% to 95% are considered necessary to prevent the virus from spreading to those who are vulnerable, including children with weakened immune systems. Wisconsin's county-by-county immunization rates show that none of the state's 72 counties came close to the 92% threshold in 2018. In fact, 40 counties had immunization rates below 80%. ___ Information from: Milwaukee Journal Sentinel, http://www.jsonline.com Claim: Nearly 50,000 students unvaccinated in Wisconsin.
Health officials say nearly 50,000 children in Wisconsin have vaccination waivers as the school year gets underway, leaving them vulnerable to measles at a time when the number of cases has grown exponentially across the country.