Although it was originally believed outbreaks in the US originated from China, the CDC revealed last week that cases likely stemmed from Europe, Cuomo said.
He added that the health agency said it's possible that rather than cases spreading in America in February and March, they could have been in the country in November or December of last year.
Because of this new information, Cuomo said it's likely that current death toll of nearly 20,000 will likely be higher.
"I think this is all going to change over time," Cuomo said of the death toll.
"And I think it’s going to be worse when it’s all said and tallied.
"I think it’s going to be worse," he added.
He said that in addition to the number of deaths increasing from last year before COVID-19 outbreaks were identified in February and March, that the number will rise from people who have died of the virus in their homes.
In the last 24 hours, confirmed 600 new cases, and an additional 232 deaths, Cuomo said.
"One of the most stubborn situations and the most stressing is the number of deaths," the Governor said.
Although both cases have been on the decline over recent weeks, Cuomo said it's "an unimaginable and painful reality that we have do deal with."
As cities across the US begin to ease coronavirus lockdowns, the New York Governor has said the state will "follow facts and data" before re-opening.
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"People have to be able to live their lives," Cuomo said.
The Governor acknowledged it's an emotional time and people want to get back to work, but he said as opposed to other states that are reopening with cases on the incline, New York will wait.
He added: "It’s not about emotion. It’s not about political position on re-opening."