One On One

Q & A – Professor Shabir Madhi

The vaccine being used in the South African Ox1Cov-19 Vaccine VIDA-Trial, led by Wits Professor Shabir Madhi, is called ChAdOx1 nCoV-19. It is made from a virus called ChAdOx1, which has been engineered to express the SARS-CoV-2 spike protein. South Africa might be taking a small step towards eradicating Covid-19 when the country enrolls its first participant in a Covid-19 vaccine trial – the continent’s first. In this interview Professor Shabir Madhi reveals the nine things to know about Africa’s first Covid-19 vaccine trial.

Why do we need a Covid-19 vaccine?

From past infectious disease outbreaks, such as smallpox and the Spanish Flu, we’ve learned that if we don’t keep the reproductive rate beneath one, we will see repeated outbreaks. The reproductive rate is how many other people each infected person will infect. The reproductive rate of SARS-CoV-2, which causes the disease Covid-19, is currently about 2.5. In some countries, lockdowns have resulted in reproductive rates of lower than one, but as soon as governments eased lockdown regulations, reproductive rates increased again. Vaccines have proven to be one of the most effective and economical ways to keep infectious diseases under control. Smallpox, for instance, was eradicated in 1979, because of widespread vaccination.

Which Covid-19 vaccine candidate will be tested in South Africa? 

We will be testing a potential vaccine developed by the Jenner Institute at Oxford University. The vaccine is called ChAdOx1 nCov-19, because it is made from a virus called ChAdOx1, which is a weakened version of a common cold virus that can’t replicate. The vaccine has been engineered to produce a type of protein that is found on the surface of the novel coronavirus. Researchers have shown that the antibodies that are produced against this protein after natural infection are able to kill – or neutralise – the virus when tested in labs. With the vaccine trial, they are trying to establish if this will also happen with people who are infected in their normal living environments.

Is the vaccine candidate being tested in only South Africa?

The vaccine is also being tested on 4 000 people in the UK – by the end of July, that number would have increased to 10 000. Soon, 30 000 people in the United States will participate in a trial and 5 000 people in Brazil have also been enrolled in a clinical trial.

Who will participate in South Africa’s trial?

The vaccine will be tested on three groups of people. The first group – 50 HIV-negative people – will be used to establish if the vaccine is safe and what type of immune response it provokes. This group will receive two jabs, four weeks apart. The vaccine will then be tested on 1 900 HIV-negative people (half of the participants will receive the actual vaccine and the other half a placebo) to determine how effective the vaccine is. People in this group will receive one jab, unless data from the first group indicates that two doses are required for an adequate immune response. The last group will be 50 HIV-positive people, who will receive two doses, four weeks apart. In the case of this group, researchers would want to establish if the vaccine is safe for people with HIV to use, and if it provokes an immune response that is comparable to the response provoked in HIV-negative people. Recent data from the Western Cape government revealed that HIV-infected people are about two to three times times more likely to die of Covid-19. 

Will the vaccine be tested on children and elderly people?

For the first two groups, only healthy adults between 18 and 65 can enrol, so no children or adults older than 65. Researchers say children are a lower priority for a vaccine because studies have shown that they’re less likely to become infected with the SARS-CoV-2 coronavirus and also less likely to fall ill with Covid-19. All the people in the HIV-positive group have to be on antiretroviral treatment and, as a result, have low amounts of HIV in their blood (also known as suppressed viral loads).

When will we know the results? 

The first participant will be enrolled on Wednesday, June 24. Researchers aim to complete enrollment across multiple sites by mid-August. They plan to follow each participant for 12 months after vaccination. The study’s investigators will be able to determine if the vaccine is effective when about 42 Covid-19 cases have been identified. They estimate that these cases will occur between December 2020 and March 2021.

How will the researchers know if the vaccine is effective?

The study investigators will regard the vaccine effective if it reduced potential Covid-19 cases among trial participants who received the vaccine by at least 60%. They will compare the Covid-19 cases among participants who received the actual vaccine and those who got a dummy jab to establish whether the groups who received the vaccine had a lower occurrence of Covid-19 cases. 

Are other Covid-19 vaccines being developed?

There are 268 Covid-19 vaccines around the world under development – and the number increases each week. Only six vaccines have reached the stage where they’re being tested on humans. Most of the vaccine candidates will never reach that stage. Researchers think we can expect about five vaccines to eventually be licensed.

Will the world be able to produce enough vaccines?

Even if we find effective vaccines, the world will not be able to produce enough vaccines for everyone by the end of 2021. The question is: who will be prioritised? Some countries argue that if they invested heavily in the development of a vaccine, they should be the first to receive it. For instance, in the case of the vaccine that South Africa is helping to test, one of the companies that will be manufacturing it, AstraZeneca, announced that because of the UK’s $79-million investment, the first 30-million doses of the vaccine would be allocated to that country. But this “vaccine nationalism” is not only morally reprehensible, it is the wrong way to reduce transmission globally [because Covid-19 spreads across borders], researchers in the Harvard Business Review write. South African researchers warn that Africa would have to fight for its right to Covid-19 vaccines, just as the continent had to do in the case of HIV treatment.