An African partner is “absolutely critical” to understanding the way in which the vaccine candidate works in different places, says Madhi. “Efficacy varies widely in different settings. You can’t extrapolate from one place to another.”
The University of the Witwatersrand (Wits) is collaborating with the University of Oxford and the Oxford Jenner Institute and vaccinated the first candidates this week. The vaccine is already being tested in the UK, and studies are planned in Brazil and the US. The diversified testing base is grounds for optimism. “Due diligence and local evidence allow informed policy-making,” he says.
Rotavirus, which is a major cause of acute gastroenteritis, provides an example. Vaccines have efficacy of 80% to 90% in high income parts of the world, compared with 40% to 60% in low- and middle-income countries.
Madhi is “cautiously optimistic” over the COVID-19 candidate’s prospects.
- In general, new vaccine development has a success rate of about 10%, he says.
- The chances may be better in this case, he says, as COVID-19 is not novel in the manner of HIV and has greater genetic stability.
- There is also a pool of understanding that has been reached through studying the genetically similar SARS and MERS viruses, he says.
- The same technology that has been employed for those viruses has been adapted for COVID-19.
- The vaccine candidate is made from a weakened version of a common cold virus, adenovirus.
- Even in a best-case scenario, Madhi sees no prospect of an effective vaccine being widely available before the middle of 2021.
COVID-19 has hit South Africa harder than any other country on the continent. That makes it a good place to test the vaccine candidate, as volunteers are likely to come into contact with the virus relatively quickly.
The study will follow up to 2,000 volunteers over 12 months. The volunteers are being encouraged to avoid risks and take precautions such as wearing masks, even though that may mean it will take longer to get the results. Madhi estimates that, given the extent of COVID-19 in South Africa, the threshold of 42 cases which will allow an assessment of efficacy will be reached in November.
There’s no pressure on the study to cut corners or come up with promising results, he said: the fact that the study is funded by the Bill & Melinda Gates Foundation and the South African Medical Research Council will ensure its independence.
If efficacy is shown, Madhi says, “that’s when the difficult work starts.” AstraZeneca, which holds the license for the vaccine candidate, would be responsible for manufacturing.
- In the unique circumstances, the company is already developing manufacturing facilities despite the lack of an efficacy readout, says Madhi.
- The company says it will be able to supply 2 billion doses, and that low-income countries will be able to get early supplies.
- But World Health Organization Director-General Tedros Adhanom Ghebreyesus said on 24 June that a huge investment is needed to ensure the quick availability of any approved COVID-19 vaccine throughout Africa.
Africa must not lag behind the developed world in getting access to any successful vaccine.
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