Walking past the site of Aspen Pharmacare’s Johnson & Johnson COVID-19 vaccine factory in Gqeberha, South Africa, last October.Credit...Siphiwe Sibeko/Reuters

The factory, in the coastal South African city of Gqeberha, formerly known as Port Elizabeth, was celebrated as a solution to the continent’s unequal access to vaccines when it announced a deal to start manufacturing Covid vaccines in November of 2021.

But no purchasers have appeared, as the slow distribution of vaccines in Africa has left health agencies with a backlog of supplies. Commercial production never started, in what officials say is an ominous sign for other African countries that had considered manufacturing Covid-19 vaccines.

Throughout the coronavirus pandemic, many African countries have lagged far behind much of the world in getting their people vaccinated — and some countries have had difficulty distributing what doses they did get.

Less than 20 percent of the total population in Africa is fully vaccinated against the coronavirus. Officials and politicians blamed wealthy countries for hoarding vaccine doses when vaccines first became available. Countries reliant on donations of vaccines were at the back of the line. Building the capacity to manufacture vaccine doses in Africa was billed as a solution to this vaccine inequity as well as a way to prepare for future pandemics.