Deadly ‘super flu’ forces more schools to close and triggers hospital restrictions, revivals of Covid-era mask mandates | 10 Dec 2025 | More hospitals and schools across the US are imposing renewed visitor restrictions and closures amid concerning spikes in a deadly “super flu,” as experts urge the public to keep watch for warning signs. Cases of the dangerous flu strain H3N2 subclade K are climbing in more than three dozen states. Detroit Medical Center has restricted visitor access to protect patients and staff from the spreading virus. New guidelines limit guest numbers, visitors under 12 and anyone 13 and up who is currently sick. The change comes after masking requirements for hospital staff and visitors in New Jersey and New York hospitals were reinstated. This year’s strain has already been dubbed the super flu in the UK, where it is pushing hospitals beyond capacity, closing schools and causing revivals of Covid-era mask mandates. [Do not comply.]