"When you talk about due the numbers, you don't know how many people died in China. You don't know how many people died in Russia. You don't know how many people died in India. They don't exactly give you a right number. Just so you understand," Trump said.
Trump has repeatedly blamed China, where the coronavirus first emerged in December last year and spread around the world, killing over one million and infecting more than 30 million people.
Attacking Trump over the handling of the Covid-19 pandemic, Biden said the president has "no plan" to fight the deadly disease and he lied to Americans.
"He still hasn't even acknowledged that he knew this was happening, knew how dangerous it was going to be back in February, and he didn't even tell you. He is on record as saying it. He panicked or he just looked at the stock market, one of the two, because guess what, a lot of people die and a lot more are going to die unless he gets a lot smarter, a lot quicker," he said.
Trump hit back, saying, "don't ever use the word smart with me."
During the first of the three presidential debates in Cleveland, Ohio, on Tuesday night which was marked by angry interruptions and bitter accusations, the two candidates fiercely clashed over a number of issues, including racism, economy and climate.