On Friday, de Blasio encouraged businesses "to move immediately to some form of mandate" for vaccinations.
It's his latest effort to fight a surge of the more contagious Delta variant.
"We tried purely voluntary for over half a year, we tried every form of incentive, so we have reached the limit of a purely voluntary system, it's time for more mandates," de Blasio said.
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When he was asked if the city would consider a mandatory COVID pass for most social activities, like France, de Blasio said it's a "direction we need to seriously consider."
"Getting vaccinated is smart in general, it's smart, if you want to attend big events, it's just smart," he said. "So, I'd say to everyone, if you want to keep going to these great things, go get vaccinated."
The mayor's remarks came just two days after he imposed a mandate on employees of the city's public hospital system and the health department's community clinics.
Those employees must either be vaccinated or face weekly coronavirus testing.
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