Health minister Zweli Mkhize announced on Wednesday that SA is now in its second wave of Covid-19 infections, in the same week that results of the Oxford AstraZeneca vaccine trial were published in international medical journal The Lancet.
With more than 6000 new cases reported in SA in the latest 24-hour cycle, the quest for a vaccine is top of mind for scientists.
The Lancet research is the first peer-reviewed data to be published on any of the leading three vaccines against Covid-19 now holding hope for the world in the worst pandemic in a century.
The other two, the Pfizer-BioNTech vaccine and the Moderna vaccine, have also shown remarkable success, but in the SA context, it’s likely to be AstraZeneca that we’ll see rolled out first.
Prof Shabir Madhi, a vaccinologist at the University of the Witwatersrand, says the strides made with all three vaccines are a major milestone: the Pfizer-BioNTech and Moderna vaccines both use novel technology called mRNA (messenger ribonucleic acid) and show protection of over 90%.
The AstraZeneca vaccine indicates protection in the region of 60% to 90% with different dosing.
“These are really stunning successes and all this has happened in a brief period of less than a year,” said Madhi. “It normally takes up to 10.5 years from human trials to licensing of a safe and effective vaccine.”
These are really stunning successes and all this has happened in a brief period of less than a year.
He added: “That’s not to say any shortcuts have been taken. It’s because processes have happened in parallel, which has really sped things up.”
But what do these successes mean for SA?
There are a number of differences both in terms of storage and the ability to scale up manufacturing of each type of vaccine.
Pricing and number of doses needed are also a consideration.
“The one extreme is the PfizerBioNTech vaccine which shows a 95% protection, but unfortunately, in its current formulation, it needs to be stored at temperatures lower than -70°C. Facilities with these capabilities are only available in very specialised academic laboratories in SA.”
It also has a shelf-life of only five days, which makes it difficult to deploy.
“In its current formulation, it is unlikely to be available in SA any time soon unless the formulation is reworked so it can be stored at higher temperatures,” said Madhi.
Then there’s the Moderna vaccine.
It was funded by Operation Warp Speed, which is essentially an American-focused entity.
“The target for this vaccine is specifically the American market, so the Moderna vaccine probably won’t be available outside the US any time in the foreseeable future and not until 2022,” Madhi explained.
Also, the cost is rather high.
The Pfizer vaccine is US$20 per dose, and the Moderna vaccine is US$30, and in both cases two doses are needed.
“So, when you’re thinking of vaccinating millions of people, that’s a lot of money,” said Madhi.
In the case of the Oxford-AstraZeneca vaccine, protection against Covid-19 averages at about 70%.
In the UK branch of the trial, 3,500 participants were accidentally given a lower dose for their first dose and a full one for their second.
Analysis of the results of this mistake showed that the group that got the lower dose for their first shot had protection of up to 90% compared to about 60% of the group that got two full doses.
“This might seem counterintuitive,” explained Madhi, “but sometimes that is how it works because of how the body responds and mounts a defence.”
Most importantly, the AstraZeneca vaccine costs about US$3 to 4 per dose, roughly a tenth of the Moderna shot, and can be produced at a scale far more quickly, as the technology required is less complex and facilities have been established for manufacture.
When you’re thinking of vaccinating millions of people, that’s a lot of money.
— Prof Madhi
It can also be stored at temperatures between 2 and 8°C and has a longer shelf life (six months) compared to the others.
“So in all likelihood, SA is best suited to the AstraZeneca vaccine out of three,” said Madhi, “but as to when that will happen, I cannot say. It largely depends on the government and any bilateral agreements they enter into.”
The results published in The Lancet look at safety and efficacy in the cases of Brazil and the UK, but in SA, because of the trajectory of the outbreak and when the first wave subsided, it has taken longer to get full results.
“For SA, we could only look at data from a safety perspective at this point and the data has been very similar to that of the UK and Brazil: across 24,000 trial participants altogether, there are no issues related to safety,” said Madhi.
“We now need to continue following up the participants until at least 45 have Covid-19 after two weeks following their second dose. Only then can we analyse and establish whether it protects. But given results from two other countries, it will be strange if we don’t show a similar protection of at least 60%.”
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