South Africa has suspended plans to inoculate its front-line health care workers with the Oxford-AstraZeneca vaccine after a small clinical trial suggested that it isn't effective in preventing mild to moderate illness from the variant dominant in the country.
South Africa received its first 1 million doses of the AstraZeneca vaccine last week and was expected to begin giving jabs to health care workers in mid-February.
The disappointing early results indicate that an inoculation drive using the AstraZeneca vaccine may not be useful.
Preliminary data from a small study suggested that the AstraZeneca vaccine offers only “minimal protection against mild-moderate disease" caused by the variant in South Africa.
The variant appears more infectious and is driving a deadly resurgence of the disease in the country, currently accounting for more than 90 per cent of the COVID-19 cases, health minister Zweli Mkhize said Sunday night.
“The AstraZeneca vaccine appeared effective against the original strain, but not against the variant,” Mkhize said.
“We have decided to put a temporary hold on the rollout of the vaccine ... more work needs to be done.”
The study, which hasn't yet been peer-reviewed, involved 2,000 people, most of whom were young and healthy. The volunteers' average age was 31.
“Protection against moderate-severe disease, hospitalisation or death could not be assessed in this study as the target population were at such low risk,” said a statement issued by Oxford University and the University of the Witwatersrand in Johannesburg.
Scientists will be studying whether or not the AstraZeneca vaccine is effective in preventing severe disease and death against the variant, Mkhize said.
Other vaccines have shown reduced efficacy against the variant, but have provided good protection from serious disease and death.
Public health officials are concerned about the South Africa variant because it contains a mutation of the virus' characteristic spike protein, which is targeted by existing vaccines. South African officials say the variant is more contagious and evidence is emerging that it may be more virulent.
South Africa will urgently roll out other vaccines to inoculate as many as possible in the coming months, Mkhize said. Other South African scientists on Sunday said the clinical trials for the Johnson & Johnson vaccine show good results against the variant.
The early results for the AstraZeneca vaccine against the variant could have far-reaching implications as many other countries in Africa and beyond have been planning to use the AstraZeneca shot. The international COVAX initiative has bought the AstraZeneca vaccine in bulk from the Serum Institute of India.
Developers of the Oxford-AstraZeneca vaccine expect to have a modified jab to cope with the South Africa coronavirus variant by autumn, the vaccine's lead researcher said Sunday.
Sarah Gilbert, lead researcher for the Oxford team, told the BBC on Sunday that “we have a version with the South African spike sequence in the works.”
“It looks very likely that we can have a new version ready to use in the autumn,” she added.
Authorities in England last week went house-to-house to administer COVID-19 testing in eight areas where the South Africa variant is believed to be spreading, after a handful of cases were found in people who had no contact with the country or anyone who travelled there.
More than 100 cases of the South African variant have been found in the UK. The testing blitz is a bid to snuff out the variant before it spreads widely and undermines the UK's vaccination rollout.
Britain has seen Europe's deadliest coronavirus outbreak, with over 112,000 confirmed deaths, but it has embarked on a speedier vaccination plan than the neighbouring European Union.
So far, the UK has given a first coronavirus vaccine jab to about 11.5 million people.