According to news agency Sputnik, Mishustin told President Vladimir Putin that he had gotten the coronavirus and would now go into self-isolation.
"I have just learned that I tested positive for the coronavirus. In this regard and as demanded by [the consumer health watchdog] I will now have to go into self-isolation and do what doctors tell me," Mishustin told Putin.
Mishustin has suggested Andrei Belousov, the deputy prime minister, to act as the head of the government temporarily. Putin has signed the decree on Belousov's appointment.
Government spokesman Boris Belyakov said that Mishustin will be treated for coronavirus infection at a medical care facility. "Mikhail Vladimirovich will be admitted to a medical institution and placed under medical observation," Belyakov told reporters.
His spokesman said Putin had been informed about his condition as soon as the test results arrived. The prime minister limited all in-person contacts several weeks ago, he said. His contacts will be isolated and tested for the virus.