Dr Stavros Nicolau, a senior director at Aspen, says the agreement with US pharmaceuticals giant Johnson & Johnson to package and distribute its vaccine across Africa assumed there would be demand for the vaccines from the World Health Organization.
He says keeping the production line going would no longer be sustainable, and the equipment would be used to make anaesthetics instead.
He said Aspen would only produce Covid-19 vaccines on an emergency basis.
Dr Nicolau said that at the height of the pandemic, there had been calls globally for Africa to produce more of its own vaccines.
He however insisted this could only happen if producers had support from international agencies, such as the WHO.