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Residents of the Chinese city of Wuhan are worried that mass COVID-19 testing efforts may spark another outbreak of the deadly virus.

Though the city is largely past the worst of the illness, which forced the sprawling metropolis into lockdown for more than two months, some residents are worried about the large crowds accumulating outside testing centers and open-air clinics, according to Reuters.

“Some people have expressed worry in the [social media] groups about the tests, which require people to cluster, and whether there’s any infection risk,” a Wuhan resident told the wire service.

New fears — and demands for tests — were sparked after small clusters of new infections were discovered last weekend, the first since the city emerged from lockdown in April.

China has reported only 4,637 COVID-19 deaths, with the majority of cases in the country coming from Wuhan. Independent experts have questioned these figures and evidence suggests the true death toll could be significantly higher.