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At least 81 employees inside a single Walmart store in Massachusetts have tested positive for the coronavirus, officials said.

The Walmart Supercenter in Worcester, about 50 miles west of Boston, was closed on Wednesday to undergo a deep cleaning after 23 employees had received positive test results. The first case was confirmed on April 8.

By Sunday, 58 additional employees had tested positive, meaning a total of 81 employees at that store had become infected with the novel virus, Worcester City Manager Edward Augustus said.

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"Our inspectional services department will inspect the facility to make sure that the cleaning was done in compliance with our guidelines," the city manager told WYCN-LD.

A total of 391 employees had undergone testing conducted by UMass Memorial Health Care on Thursday and Friday.

Walmart spokesman, Charles Crowson, told Fox News that those numbers included staff who work inside the same building, including both Walmart employees as well as workers employed by independent vendors.

A city inspection conducted Tuesday revealed employees were not wearing face masks, violating a recent city order requiring all essential workers to wear personal protective gear, the Worcester Business Journal reported.

Crowson, a senior manager for corporate communications at Walmart, said the company has required all staff to wear face masks while on the job since April 20.

He told the Journal the company has implemented other safety precautions, including testing workers' temperatures at the start of each shift and reducing store hours to allow more time for cleaning.

Aisles have been arranged to permit only one-way traffic, and plastic barriers have been set up to separate checkout aisles, he added.

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Advocates argue that both the city and company have not done enough to safeguard the health of essential workers during the pandemic, WYCN-LD reported.

"They're already vulnerable. They have to go out there and make money, they can't afford to say, 'No, I got to take the day off, now is really not time.' They need food, they need to keep a roof over their heads," said Joanne Suarez, a community health advocate at The Family Van, a mobile clinic providing free medical screenings in underserved Boston neighborhoods.

Coinciding with International Workers' Day, some grocery workers in Massachusetts were expected to participate in a national “sickout” Friday, calling out of work to demand more pay and safer working conditions amid the pandemic.

The national protest involved employees at Target, Whole Foods, Amazon, Instacart, FedEx and Walmart, but it was unclear how many in the greater Boston area participated.

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Last month, dozens of workers employed by Stop & Shop, Whole Foods, Trader Joe's and Shaw's food stores stood six feet apart in Boston’s South End claiming they were being forced to work during the coronavirus health crisis without adequate PPE.

In the hours following the protest, Boston Mayor Marty Walsh posted a video message on Twitter thanking grocery store employees for providing a critical service to the public amid the coronavirus crisis.