South African biotech company Aspen Pharmacare says it has struck an initial deal with Johnson & Johnson to produce its experimental COVID vaccine at a factory in South Africa, sending the company's shares higher.

Aspen Pharmacare, which had invested more than $184 million in a Port Elizabeth facility, is the largest drug manufacturer in Africa and can make 300 million doses a year, Bloomberg News reported. The pharmaceutical group will perform filing, formulation and packaging of the U.S. company's potential treatment.

Shares of Aspen Pharmacare rose more than 4% on the Johannesburg Stock Exchange while shares of Johnson & Johnson dropped 6% year to date following the announcement.

The candidate vaccine is currently being evaluated in tests after they were temporarily suspended last month after a patient illness. On Oct. 23, Johnson & Johnson announced it was set to resume third-stage clinical tests of its experimental COVID vaccine in the U.S. after "no proof" was established that its vaccine triggered the illness.

South Africa has reported 726,000 COVID cases - the biggest figure on the African continent - and the country is conducting at least four additional tests of a potential COVID vaccine, including Johnson & Johnson's coronavirus vaccine candidate, reports said.

The Aspen-Johnson & Johnson preliminary agreement is subject to the completion of the technology transfer protocol and finalization of certain production conditions.

According to Aspen Pharmacare chief executive officer Stephen Saad, the company has invested globally in "sterile capability and are determined to play a role in the production of vaccines," Smarter Analyst quoted him as saying. Saad added that Johnson & Johnson had chosen Aspen to be its vaccine partner and that the deal will be given top priority.

The Durban-based vaccine maker is looking to test its COVID vaccine in children aged 12 to 18, subject to regulations soon. Competitor Pfizer has already started testing its messenger RNA vaccine in children as young as 12.