British drugmaker AstraZeneca said Saturday that early trial data showed its COVID-19 vaccine appeared to offer limited protection against mild disease caused by the South African variant of coronavirus.
“In this small phase I/II trial, early data has shown limited efficacy against mild disease primarily due to the B.1.351 South African variant,” the pharmaceutical firm said in response to a report published by the Financial Times.
“However, we have not been able to properly ascertain its effect against severe disease and hospitalization given that subjects were predominantly young healthy adults,” the spokesperson said.
AstraZeneca noted that none of the over 2,000 participants in the trial carried out by South Africa’s University of the Witwatersrand and Oxford University had required hospitalization or died.
The company said it believed its vaccine could protect against severe disease, the Reuters news agency reported.
Scientists say there’s no evidence the South African variant is more serious than the original virus but it may be more contagious.
Several new variants — each with a cluster of genetic mutations — have sparked fears over an increase in infectiousness as well as suggestions that the virus could begin to elude immune response, whether from prior infection or a vaccine.
The new variants — along with another linked to Brazil — have mutations to the virus’s spike protein, which enables the virus to latch onto human cells and therefore plays a key role in driving infections.
One mutation in particular — known as E484K and found in the South Africa and Brazil strains but not the one in Britain — has experts particularly worried about immunity “escape.”
There have been concerns that current vaccines may be less effective against the South African variant because it contains a mutation of the virus’ characteristic spike protein that existing vaccines target.
Pfizer and BioNTech, whose vaccine is being used in Israel’s world-leading vaccine drive, said last month that early tests suggest their immunization would be protective against the variants from South Africa and Britain. US biotech firm Moderna has said that lab studies suggest its vaccine, too, would protect against the variants.