Previous cases were identified in Newark, Morristown, Garwood and Old Bridge.
Nearly two dozen ShopRite stores in New Jersey are imposing customers limits to stop the spread of coronavirus.
The East Windsor employee first reported symptoms on March 12, was subsequently sent home and has not yet returned to work, reports said.
Other employees at the location were notified of the positive case, and the store is being thoroughly sanitized, officials said.
There were nearly 14,000 cases of COVID-19 statewide as of Monday, according to data from Johns Hopkins University.
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