(Bloomberg) -- A number of schools across China halted classes earlier this week to stem the spread of Covid and other pathogens ranging from flu to the norovirus, as the country begins to see a comeback of other illnesses after pandemic restrictions were eased. 

Ten second-graders in the same classroom tested positive for Covid on rapid antigen tests last weekend in eastern e-commerce hub Hangzhou, prompting local education authorities to suspend their class for four days starting Monday. The students were likely infected for the first time, officials said. 

Shanghai suspended in-person teaching in an elementary school class after four students were diagnosed with the flu and others developed similar symptoms. Flu cases — and subsequent class suspensions — were also reported in other schools across Zhejiang province, Chinese capital Beijing and nearby city Tianjin.

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The fresh surges parallel what was seen globally after countries eased Covid social distancing rules which kept other illnesses largely at bay. The “twindemic,” as the tandem waves of Covid and influenza has been termed, stands to get worse in China which saw years of some of the world’s strictest measures, followed by one of its fastest pivots back to normal life.

China’s unexpected rush to dismantle nearly all pandemic restrictions in early December unleashed the world’s biggest Covid outbreak, with nearly 90% of the country’s 1.4 billion population infected in less than two months. While the reopening wave appears to have ebbed, the national CDC still reports around 10,000 Covid cases each day that were confirmed by laboratory tests.

While lockdowns and mass testing have eased as China moves on from its Covid Zero policy, authorities still grant schools the ability to halt in-person teaching — either by individual grade level, or the entire campus — to prevent wider outbreaks caused by Covid and other infectious diseases. I

t wasn’t unusual for schools to pause classes even before Covid, when flu and other pathogens to which children are particularly susceptible triggered student clusters. 

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Beijing’s CDC said Wednesday that it’s seeing outbreaks of flu and norovirus this month, mostly at schools and kindergartens. Cases of influenza are also creeping up as pre-pandemic normalcy returns. China’s flu positivity rate jumped to 3.4% from 0.7% in the week ending Feb. 12, according to CDC data.

The country’s Chinese Center for Disease Control and Prevention also warned of outbreaks of norovirus, which causes fever, vomiting and diarrhea; hand, foot and mouth disease; and chicken pox, all of which might easily erupt in schools as students mingle indoors. 

--With assistance from Daniela Wei.

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