Workers at care homes in New York state must be tested for coronavirus twice a week under new rules laid out by Democratic governor Andrew Cuomo.
Care facilities that fail to meet requirements intended to stem infections will lose their operating licenses, Mr Cuomo said on Sunday.
The mandate come as New York weighs options for relaxing other lockdown measures.
Parts of the state and neighbouring region could reopen business on 15 May.
New York has been the epicentre of the US coronavirus outbreak, with 26,670 deaths and 335,395 cases as of Sunday.
The US has seen a total of 1,327,720 cases and 79,495 deaths from the virus.
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