‘Vaccine trial unable to give proof of full efficacy in variant discovered in SA’

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Professor of Vaccinology at Wits University, Shabir Madhi, says the vaccine trial done by his team in South Africa could not give proof of the vaccine’s full efficacy against the variant of COVID-19 discovered in the country. He was participating in a media briefing by the Department of Health and scientists to update South Africans on the COVID-19 vaccines.

The briefing was held after AstraZeneca’s announcement that its vaccine only offers limited protection against mild disease caused by the variant that has been discovered in South Africa.

South Africa has already purchased 1.5 million doses of the vaccine from the Serum Institute in India, of which one million doses arrived in South Africa; with the vaccination of healthcare workers expected to start this week.

In the study by Wits University, with 2 000 participants aged between 18-25, the participants had mild to moderate symptoms of the virus.

The study found that a two-dose regimen of the AstraZeneca vaccine provides minimal protection against mild-moderate COVID-19 infection from the  COVID-19 variant that was discovered in South Africa in mid-November 2020.

However, the study did not assess efficacy against severe COVID-19 infection from the variant.

Wits say the Oxford University is, however, working on producing a second generation of the vaccine, which will be adapted to the COVID-19 variants that have been discovered.

Prof Madhi says, up until the end of October 2020, the vaccine showed potential. People who took just a single dose of the vaccine were 75% less likely of becoming infected by COVID-19. However, with the emergence of the 501.V2 variant in South Africa, the AstraZeneca vaccine was not as effective.

Prof Madhi says the findings of the study will force them to rethink the approach to the virus.

“Recent data from a study in South Africa sponsored by Janssen which assessed moderate to severe disease, rather than mild disease, using a similar viral vector, indicated that protection against these important disease endpoints was preserved. This could be relevant to the ChAdOx1 nCoV-19 vaccine, which has been developed using similar technology as the Janssen vaccine, and for which vaccine-induced immune responses are also similar.

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 the population against severe disease,” the professor says.

Vaccine rollout should be suspended

The Chair of the Ministerial Advisory Committee on COVID-19 vaccines, Professor Barry Schoub has suggested that the rollout of AstraZeneca’s vaccine should be suspended.

“The AstraZeneca vaccine studies that Prof Madhi did, provides some rather disappointing initial studies. But as he pointed out, there may well still be effective utilisation of AstraZeneca. For example, we need to look at the cell mediated immune responses; we may need to look at combination of AZ vaccine with other vaccines which may in fact give a synergistically good response. So I just think we need to maybe suspend use of AstraZeneca, but investigate it more fully, can we utilise it more effectively,” says Prof Schoub.

– Additional reporting by Ditaba Tsotetsi. 

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