A mutated strain of the novel coronavirus similar to the one identified in Britain has been reported in South Africa, driving a second wave of infections in areas where it was thought people had acquired immunity, according to a new study.
In Cape Town and surrounding areas, almost half the population had Covid-19 by the end of the summer, but cases there have been rising again since October, the South African researchers said in a paper published on the preprint website Medrxiv.org, which means it has not been peer-reviewed.
The strain causing the second wave carries N501Y, the mutation found in the British variant that prompted the government to impose new lockdowns and some countries to close their borders to British travellers.
Get the latest insights and analysis from our Global Impact newsletter on the big stories originating in China.
But the researchers said genetic tracing suggested the South African strain had nothing to do with the one found in Britain.
“It is possible that high levels of population immunity could have driven the selection of this lineage,” said the team led by Professor Tulio de Oliveira from the University of KwaZulu-Natal in Durban.
A government epidemiologist in Shanghai said the study could disrupt the mass vaccination programmes being rolled out in countries like China.
Inoculating a large proportion of the population could build herd community but also lead to new strains, she said.
South Africa has reported more coronavirus infections than any other country in Africa, with new cases peaking at about 13,000 a day in July. Numbers had been in decline, which researchers said was most likely due to herd immunity.
According to a survey conducted in August, about 40 per cent of Cape Town residents had antibodies specific to the Sars-CoV-2 virus in their blood.
In other areas with worse infection rates, like Eastern Cape province and Nelson Mandela Bay, the prevalence of the pathogen could be even higher, de Oliveira said.
Antibodies are generated by the immune system to fight infection and bind with the virus to stop it from entering host cells.
According to the researchers, the more people that have antibodies, the more difficult it is for the virus to spread. For a time, new infections and deaths in South Africa dropped so low it appeared the coronavirus was on course to disappear, they said.
But the new strain dashed those hopes. According to a study by British researchers, the N501Y variant’s infectivity could be 70 per cent higher than that of earlier forms.
In Britain and South Africa, the new strains have established their dominance in recent months.
It could become even more well established in South Africa, which is home to the world’s largest number of people with HIV.
“One concern has been the possibility of prolonged viral replication and intra-host evolution in the context of HIV infection,” the researchers said.
The team said South Africa was not equipped to track or contain the spread of the new strain alone.
“These data highlight the urgent need to … limit the national and international spread of this lineage,” they said.
The US Centres for Disease Control and Prevention (CDC) said on Tuesday that a mutated strain posed several potential threats.
Besides its higher infectivity, it could cause more severe illnesses and may dodge detection by some testing kits that targeted only the mutated area of the viral genes.
But the biggest threat, the CDC said, was its ability to evade vaccine-induced immunity.
“Once a large proportion of the population is vaccinated, there will be immune pressure that could favour and accelerate emergence of such variants by selecting for ‘escape mutants’,” it said.
A Beijing-based microbiologist said the global research community had been monitoring coronavirus mutations and to date it had been much more stable than HIV or flu viruses that mutate much faster.
Many experts believed the pandemic would end before an escape mutant occurred, he said.
But if they were wrong, the global vaccination efforts would end up as “a big gamble”, he said.
More from South China Morning Post:
This article Coronavirus mutation similar to British variant identified in South Africa first appeared on South China Morning Post