SA's AstraZeneca study ‘rude awakening, turning point’ in Covid vaccine development – Shabir Madhi

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  • AstraZeneca's Covid jab showed to provide minimal protection against mild-moderate disease caused by the new variant in SA
  • The study findings led to the suspension of the vaccine's rollout in the country in February
  • But these results are a strong indication that developing improved vaccines are necessary, said Professor Shabir Madhi

The Oxford-AstraZeneca Covid-19 vaccine was one of the first to enter clinical trials in early 2020, but it has recently had a flurry of suspensions in countries worldwide who planned to roll it out.

This suspension started in South Africa, after the vaccine was tested in a small study and was found to offer low protection against mild to moderate disease caused by the new variant. Named B.1.351 (or 501Y.V2), this variant is highly infectious and quickly started to dominate during second-wave infections.

The findings of this trial were published in the peer-reviewed New England Journal of Medicine (NEJM) this week.

The AstraZeneca jab was previously considered a global changer, as it was cheaper and had simpler storage requirements than other vaccines in development. It goes without saying that the study’s results were therefore hugely disappointing, Professor Shabir Madhi, Executive Director of the Vaccines and Infectious Diseases Analytics (VIDA) Research Unit at Wits, and lead of the SA trial said in a news release.

Despite this, he said that the publication of their research “validates the findings and makes a compelling case for the development of second-generation vaccines worldwide.”

First-generation vaccines are designed to respond to the original SARS-CoV-2 virus, while second-generation vaccines use technology and design innovation to provide protection against the constantly evolving variants, some of which have a worrying number of mutations, known as variants of concern (VoC). 

Suspension

Prior to the discovery of 501Y.V2 in South Africa, the South African National Department of Health (NDoH) had received approximately 1 million doses of the AstraZeneca jab in February 2021. This was because a previously published analysis in December 2020 showed an overall vaccine efficacy of 66.7% in the UK and Brazil. Efficacy refers to the percentage reduction of a disease within a clinical trial setting.

“We were in a state of euphoria about the high efficacy of several Covid-19 vaccines against the original virus, but then the AstraZeneca study threw us a curve-ball,” said Madhi.

In their new study in the NEJM, just over 2 000 healthy participants were enrolled between June and November 2020. Unfortunately, they found that two doses of the jab had no efficacy against non-hospitalised mild to moderate Covid-19, due to 501Y.V2.

“A trial enrolling just 2 026 participants is considered small, while phase 3 trials enroll tens of thousands of participants. Yet the startling data that our small trial generated was irrefutable, and the implications profound,” explained Madhi.

Vaccine should still be rolled out

Although the SA government decided to suspend the use of the AstraZeneca vaccine, and the 1 million doses were later sold to the African Union, Madhi noted that the jab may still help protect high-risk individuals with co-morbidities from contracting severe Covid disease, and having to be hospitalised, mechanically ventilated, or dying.

“The AstraZeneca vaccine remains essential in the arsenal against this virus, particularly in Africa, which has already received 14 million doses of this vaccine as the Covid-19 immunisation programme starts in multiple countries,” he said.

The World Health Organization (WHO) also defended the AstraZeneca jab, and in February 2021 recommended it still be rolled out, even in countries where the variant or other similar VoC were circulating.

Madhi also believed that while the jab, as many other first-generation jabs, are unlikely to interrupt the spread of the virus or protect against mild infection from VoC, it “could still provide the only sustainable option to prevent flooding ... hospitals with severe Covid-19 cases, and to mitigate Covid-19 deaths once the third wave hits.”

However, several countries worldwide have suspended the use of this vaccine after reports that it might be linked to blood clots, although Europe's drug regulator stated this week that there is “no indication” it is caused by the jab.

Second-generation vaccine underway

According to Madhi, plans to modify the AstraZeneca vaccine to target the 501Y.V2 variant are currently underway.

The South African study increased awareness worldwide of the necessity of developing vaccines that target variants specifically, he said.

“The findings of our [Oxford AstraZeneca Covid-19 vaccine] study are truly a turning point in Covid vaccine development – and a rude awakening,” he said.

“This one small South African study has alerted the world to the fact that second generation Covid-19 vaccines will be required to provide protection against inevitable and persistent SARS-COV-2 variants.

"If we had not conducted this trial in South Africa, the world would be none the wiser.”

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