"The testing shortfalls make it nearly impossible to understand the extent of the pandemic - let alone put measures in place to stop it," said Stacey Mearns, a senior technical advisor at the IRC, an international nongovernmental organisation.
Confirmed Covid-19 cases more than doubled in July across African countries, rising by 500% in the past two months, the IRC said in a statement on Thursday.
Poor access to data on the number of cases is impacting the ability to carry out an effective response, and the IRC said it fears it is "fighting the epidemic in the dark", urging an increase in funding and international support.
The New York-based NGO pointed to statistics on testing comparing African countries to elsewhere in the world.
Rich countries such as the UK have carried out more than 205,000 tests per million people, the IRC said.
Testing in African countries is considerably lower with Tanzania conducting 63 tests per million, Niger performing 373 tests per million, Chad carrying out 383 tests per million, the Democratic Republic of Congo doing 467 tests per million, and Burundi completing 563 tests per million.
"These countries need international support to increase their testing capacity," said the IRC's Mearns.
The African continent has registered more than 893,000 cases of Covid-19, and almost 19,000 deaths, according to the Africa Centres for Disease Control and Prevention.
