'In science we don't go for the second-best option': Health ombud Makgoba speaks out on AstraZeneca vaccine
SA health ombud and molecular immunologist Prof Malegapuru Makgoba is fiercely opposed to the rollout of the AstraZeneca Covid-19 vaccine in SA, saying that from a scientific and public health point of view it would be irrational.
“The AstraZeneca vaccine is not efficacious. It was efficacious against the original, wild virus but it is not against the variant dominant in SA,” he said.
The new variant, known as B1.351 or 501Y.V2, is the current dominant variant in SA.
“Both the government and scientists have made the right decision and done what is scientifically acceptable by pausing the rollout,” he said.
Makgoba said the Johnson & Johnson Covid-19 vaccine was the only one proven to be efficacious against B1.351 in a clinical study — offering 57% protection. The others have not undergone such a clinical trial.
“The AstraZeneca vaccine is way below this (at 22%) and significantly below the 50% minimum efficacy threshold required by the FDA. In science we don’t go for the second-best option,” he said.
The Oxford AstraZeneca option provides the least protection — even against the original virus — of all seven of the approved vaccines to date, with Pfizer BioNTech (95%) and Moderna (94.1%) at the top.
“I had put it at 62% from the original Lancet paper, the latest WHO figure puts it at 63% efficacy. It is still the lowest efficacy of all the Covid-19 vaccines,” said Makgoba.
Taking this 62% efficacy, 20 million more people would need to be vaccinated with the AstraZeneca vaccine in SA to get roughly the same result as a vaccine like the Pfizer candidate.
In other words, said the health ombud, SA would need to vaccinate 60 million people with the AstraZeneca vaccine to immunise 40 million people to achieve herd immunity — compared to injecting 40 million people with the Pfizer or Moderna vaccines to get nearly 40 million people protected from Covid-19.
“How are you going to find the 20 million people who got vaccinated but do not have immunity? Through testing and that would be costly.
“Vaccinating 60 million people is quite costly and revaccinating the other 20 million would just add to the cost. All this with no guarantees of protection or with minimal clinical benefits.”
Makgoba said South Africans needed to be treated with respect and dignity in the midst of this pandemic.
It is going to be our scientists, our data to guide us as South Africans
The health ombud commended the Oxford AstraZeneca principal investigator Prof Schabir Madhi and his team for conducting a clinical study which had produced critical and timely results for SA.
Despite the disappointing AstraZeneca results in the SA study, Madhi has stated the vaccine was still likely to be effective against severe Covid-19 infection and should be offered to people at higher risk of developing severe disease, in the absence of alternatives.
Makgoba was critical of how the AstraZeneca trial was conducted outside SA and of the analysis, released at the end of November.
“By their own admission they made a miscalculation with doses and this was a scientific flaw,” he said, referring to the volunteers who were given half doses and then full doses, instead of two full doses a month apart, which offered 62% protection.
The half dose-full dose regimen had much better results — at 90%, pushing the average efficacy up to 70% — but nobody has explained the underlying scientific mechanism for the 90%.
The only way to know is to compare the results of half and full doses in separate clinical trials, he said.
“The end point is determined based on the dosages in a Phase III study ... you want to compare apples to apples.”
Combining the outcomes of the Brazil and UK trials for the analysis was a flaw, said Makgoba.
“You have a large population study of the standard dose and a very small population study of half dose-full doses,” he said, raising concerns also that the vaccine had not been tested in a large representative sample of people above 65 years old in the half dose and full dose study.
“It is unscientific to extrapolate, in the absence of data in a Phase III clinical trial, that the AstraZeneca vaccine would protect against severe disease caused by the variant when it failed to protect against mild and moderate disease,” he said. “Phase III studies are about data and not about scientific extrapolations.”
Makgoba, who launched the SA AIDS Vaccine Initiative, said: “We have to do a proper clinical trial if we need to know if the vaccine does prevent severe disease. No other country is going to solve this question for us. It is going to be our scientists, our data to guide us as South Africans.”
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