BLANTYRE, Malawi — Manhunts have begun after hundreds of people, some with the coronavirus, fled quarantine centers in Zimbabwe and Malawi while authorities worry they will spread COVID-19 in countries whose health systems can be rapidly overwhelmed.

In Malawi, more than 400 people recently repatriated from South Africa and elsewhere fled a center at a stadium in Blantyre, jumping over a fence or strolling out the gate while police and health workers watched. Police and health workers told reporters they were unable to stop them as they lacked adequate protective gear.

At least 46 escapees had tested positive for the virus. Some of those who fled told reporters they had bribed police.

And in Zimbabwe, police spokesman Paul Nyathi said officers were “hunting down” more than 100 people who escaped from centers where a 21-day quarantine is mandatory for those returning from abroad.

“They escape and sneak into the villages … We are warning people to stop sheltering them. These escapees are becoming a serious danger to communities,” Nyathi said.

Nearly all of Zimbabwe’s 75 new cases this week came from the centers that hold hundreds of people who have returned, sometimes involuntarily, from neighboring South Africa and Botswana.