Health officials placed South Africa’s distribution of the Oxford-AstraZeneca vaccine on hold after questions were raised about its efficacy.
During a media briefing on Sunday, February 7 Professor of Vaccinology at Wits University Shabir Madhi said the vaccine trail conducted by his team found there is little proof of the vaccination’s full efficacy against the local variant of COVID-19.
According to Madhi, who led the clinical trial of the Oxford/AstraZeneca vaccine candidate locally, the study found the vaccine showed “tremendous potential” up until October 2020 when the variant emerged.
Just 14 days after taking the first of two jabs, participants showed a 75% lesser likelihood of becoming infected with COVID-19.
However, after the 501Y.V2 variant spread rapidly throughout the country, the study then changed to examine the vaccine’s potency against the original virus as compared to the new strain.
“Much of the antibody induced by the vaccine was not actually active against the variant circulating in SA,” Madhi explained.
“When we analysed individuals in terms of how well the vaccine worked against the variant, there was very little difference between the vaccine group and placebo group. However COVID vaccines really remain the only sustainable option of reducing risk of severe disease and death.”
According to Professor Salim Abdool Karim, however, who is one of the country’s leading COVID-19 experts, this does not spell doom and gloom.
He said that the vaccines created by Pfizer and Moderna fair reasonably well against the 501Y.V2 variant. He added that there is hope that the Johnson & Johnson vaccine will show a smaller decline in efficacy against the variant, making it a plausible choice for rollout.
“Covid vaccines remain effective against existing variants. The next set of vaccines will be made from the 501Y.V2 variant and so they are likely to be effective against the 501Y.V2 variant. We are expecting two kinds of vaccines: the first are 501Y.V2 boosters, and we have already heard about the good progress they are making on these boosters,” he said.
“A next-generation of vaccinations is intended to be much broader and will cover you from the current and future variants. That will take a little longer to develop.”
Karim says the rollout of the AstraZeneca vaccines, which have already landed, will need to be put on a temporary hold.
“We can still proceed with our rollout but we need to do it wisely by taking a stepped approach,” he said.
South Africa received a million doses of the AstraZeneca vaccine from the Serum Institute of India last week, and another batch of 500 000 doses will be delivered in March. The vaccine has previously been shown to have an efficacy of between 63% and 90% on two doses, but to date it was not certain how effective it would be against new Covid-19 variants.
According to AstraZeneca, it is currently adapting its vaccine to protect against the 501Y.V2 variant and the clinical development is expected to advance quite rapidly.