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The roll-out of the Oxford/AstraZeneca vaccine in South Africa has been put on hold after a study – yet to be peer-reviewed – reported that the vaccine doesn’t appear to offer strong protection against mild and moderate cases of the new SARS-CoV-2 variant dominating South African infections.
The work was presented by the author at a conference in the presence of the South African Minister of Health Dr Zweli Mkhize and other experts. The 501Y.V2 variant was first identified in late 2020 and it is now responsible for 90 percent of the infection in the African country.
The new study is based on a clinical trial led by Shabir Madhi, Professor of Vaccinology and Director of the Vaccines & Infectious Diseases Analytics (VIDA) Research Unit at the University of the Witwatersrand. The trial was conducted using approximately 2,000 participants between the ages of 18 and 65.
At the beginning of the trial back in October, the vaccine showed “tremendous potential” with an efficacy of 75 percent two weeks after the first injection. The data from the full trial has shown a dramatic drop in the ability of the vaccine to stop people from developing mild and moderate COVID-19.
“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,” Madhi said during the press conference. “Much of the antibody induced by the vaccine was not actually active against the variant circulating in SA.”
This news is obviously disappointing, but scientists want to stress that is not absolutely terrible. Alternative vaccines such as the Pfizer/BioNTech and Moderna vaccines continue to be effective, although the variant still has an edge compared to the original clinical trial.
The South African clinical trial on the one-shot Johnson & Johnson/Jensen vaccine assessing moderate to severe disease showed that the vaccine was still effective at preventing the most serious conditions and death, even in the case of the 501Y.V2 variant. Given the similar approach in vaccine technology between the Jensen and Oxford vaccines, this suggests that people around the world that already received the latter would at least be protected against the most damaging cases of COVID.
“These findings also force us to recalibrate thinking about how to approach the pandemic virus and shift the focus from the aspirational goal of herd immunity against transmission to the protection of all at risk individuals in population against severe disease,” Madhi added in a statement.
Viruses mutate constantly, even more so when they have a chance to spread across large swathes of the population, which happened in many countries across the world over the last several months. Researchers are already looking at how to modify vaccines and boosters to continue protecting individuals.
“Efforts are underway to develop a new generation of vaccines that will allow protection to be redirected to emerging variants as booster jabs, if it turns out that it is necessary to do so,” explained Sarah Gilbert, Professor of Vaccinology at the University of Oxford, who worked on the vaccine.
“We are working with AstraZeneca to optimise the pipeline required for a strain change should one become necessary. This is the same issue that is faced by all of the vaccine developers, and we will continue to monitor the emergence of new variants that arise in readiness for a future strain change.”
For more information about COVID-19, check out the IFLScience COVID-19 hub where you can follow the current state of the pandemic, the progress of vaccine development, and further insights into the disease.
