NAIROBI (Reuters) – African countries must carry out more coronavirus testing and make people use masks, a regional disease control body said on Thursday as cases topped half a million in the continent.

New cases in Africa were up 24% over the past week, with data from governments and the World Health Organization showing it had 512,499 confirmed COVID-19 cases, with 11,930 deaths.

“The pandemic is gaining full momentum,” John Nkengasong, head of the Africa Centres for Disease Control and Prevention (CDC), told a virtual news briefing from Addis Ababa.

Nkengasong said African countries, many of which do not have reliable data, must adopt an aggressive approach to encourage the wearing of face masks and ramp up testing and tracing.

“This will save lives and save (the) economy.”

Egypt, Nigeria, South Africa, Ghana, and Algeria account for 71% of infections on the continent, Nkengasong said.

Some governments have been reluctant to acknowledge epidemics or to expose crumbling health systems to outside scrutiny, while others are either too poor or conflict-ridden to carry out significant testing.

Nkengasong said it was inevitable that as cases rise, hospitals will become overwhelmed.

“That is something that is happening already. We will continue to see it as the pandemic expands,” he added.

Although many have also started gradually easing lockdowns to reopen hard-hit economies, governments are conscious that opening up too quickly could lead to a spike in new cases.

The African Union Commission said on Thursday it had launched a consortium for vaccine clinical trials to be headed by the Africa CDC, which aimed to secure more than 10 late stage vaccine clinical trials as early as possible.

South Africa and Egypt are already running human trials for a potential vaccine.