New York City Health Committee Chair Mark D. Levine on Saturday cheered a large crowd of New Yorkers celebrating Joe Biden’s presidential victory, but a day later warned that the city was in the midst of a “2nd wave” of the coronavirus pandemic with cases and hospitalizations piling up.

“An emotional crowd in Times Square watching @jbiden & @KamalaHarris make history as Pres- & VP-elect,” Levine tweeted Saturday night. “Chants of ‘USA! USA!’”

The tweet included a video of New Yorkers standing shoulder-to-shoulder, many without masks, and just about everyone failing to abide by social distancing rules.

But less than 24 hours later, Levine’s festive tone had dramatically shifted as he warned that New York City is not approaching or at risk of a second wave of the coronavirus but is in the middle of one.

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“Cases, positivity, hospitalizations are all increasingly sharply,” Levine tweeted, adding: “It’s time to start rallying New Yorkers—again—to flatten the curve.”

Levine advised that, to flatten the city’s second wave, residents should work from home if they' are able to, avoid indoor gatherings with people outside their household, and get tested regularly.

He further advised that residents abide by the “core four” rules of the coronavirus pandemic: “#WearAMask, wash your hands, stay home if you don’t feel well, (and) keep 6 ft. apart where possible.”

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“We have many advantages now as we face NYC’s 2nd wave that we didn’t in the 1st wave—widespread mask usage, far more testing, better prepared hospitals,” Levine wrote. “But the risks now remain all too real. This is still a deadly and debilitating virus. It’s time for NYC to rally again.”

Fox News has reached out to Levine and Mayor Bill De Blasio’s office seeking comment but has not heard back at the time of publication. 

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New York was one of many major metropolitan cities in the nation where large crowds of people, in evident violation of safety guidelines, celebrated Biden’s win. Many city leaders who are on record this year warning resident to exercise caution, were noticeably silent on health matters as they cheered on the celebrations.