Research by South African scientists suggests that antibodies triggered by exposure to the country's dominant coronavirus variant can prevent infection by other variants, the scientists said on Wednesday.

The findings in laboratory studies offer hope that COVID-19 vaccines based on the 501Y.V2 variant first identified late last year could protect against multiple variants circulating in different parts of the world.

The more contagious variant drove a second wave of infections in South Africa that peaked in January and is believed to have spread to many other countries in Africa and other continents.

"We used plasma ... from people that were infected in this latest wave with the 501Y.V2 and we used it against the first-wave virus, ... what we found is that it could neutralise, OK not as well as it could neutralise itself but it's not bad at all," Alex Sigal from the Africa Health Research Institute told a news conference.

Sigal said vaccines designed with the 501Y.V2 variant in mind "might be cross-protective to other variants, ... this gives you some idea how this problem of variants can be solved".

Penny Moore, a professor at the National Institute for Communicable Diseases, said the antibody response from the 501Y.V2 variant was only reduced threefold against the first-wave virus, whereas the response from the first-wave virus was reduced nine-fold against 501Y.V2.

"It's not that the antibodies that are triggered by 501Y.V2 are somehow magical, there is a drop-off, ... but unlike the antibodies triggered by the original variant they seem to somehow have a little bit more breadth," she told the same briefing.

Salim Abdool Karim, a top government adviser on Covid-19, said major vaccine manufacturers including Pfizer, AstraZeneca and Johnson & Johnson were already making vaccines based on the 501Y.V2 variant. Moderna had already adapted its shot and was putting it into human studies, he added.

He predicted that by the end of 2021 most vaccine manufacturers would have adapted their shots, "not because they are specifically worrying about the virus coming from South Africa ... but because key mutations in the 501Y.V2 are actually also present in many other variants".

Health Minister Zweli Mkhize said the research was encouraging and that genomics surveillance had helped the government respond to the pandemic.

South Africa has recorded by far the most Covid-19 infections and deaths on the African continent, at 1.5-million cases and over 50 000 fatalities to date.