Covid-19 has killed four Kenyan health workers and infected 450, the health ministry said on Wednesday, as word emerged of a slew of cases in Kenya's biggest maternity hospital.

"Health workers handling patients with confirmed or suspected cases of coronavirus disease face an increased risk of exposure to the virus," Rashid Aman, the chief administrative secretary at the ministry of health, told a news briefing.

At least 41 of the staff at Pumwani maternity hospital in the capital Nairobi have been infected, said Patrick Amoth, the acting director general of health at the health ministry, adding that the cases were mild.

"Nobody has gone to hospital for care, and we are hopeful that they will be able to pull through without developing any symptoms of COVID," Amoth told the private Citizen TV on Tuesday.

Nairobi-based Doreen Lugaliki, who worked at a different Nairobi hospital, became Kenya's first doctor to die of the virus last week.

There was no immediate comment from the doctors and nurses unions.

Kenya has confirmed 11,252 confirmed of the disease and 209 deaths, the ministry said.