Covid-19: a vaccine tested in South Africa, a first on the continent

About twenty volunteers have already received an injection. They are the first participants in the very first clinical trial in Africa for a vaccine against Covid-19. Officially announced on Tuesday June 23, this test conducted by the Wits University of Johannesburg in South Africa could constitute a major turning point in the fight against the coronavirus on a continent where the spread is still in an acceleration phase and where more than 330,000 people have already been infected.

The vaccine used in this trial is ChAdOx1 nCoV-19. Developed in April by the University of Oxford, it is considered to be one of the most promising among the hundred in development. Outside South Africa, clinical trials of this vaccine are being carried out in the United Kingdom, Brazil and another is planned in the United States.

>> Read also: "Covid-19: why a vaccine developed in Oxford gives rise to so much hope"

A phase 2 trial

This test does not yet aim to assess the efficacy of ChadOx1 nCov-19 against the disease. "The objective, for now, is to make sure that the vaccine is not dangerous for patients [that there are no side effects, Editor's note] and to measure the response of the immune system" , says Lee Fairlie, a pediatrician at the University of Wits who oversees one of the clinical trial sites, contacted by France 24. "This is called a phase 2 trial, during which to determine what is the dose of a vaccine that produces the best immune response ", specifies Pierre Saliou, vaccine specialist and president of the Intervention group in public health and epidemiology (GISPE), contacted by France 24.

In all, about 2,000 South Africans are expected to participate in this phase, which is expected to last approximately one year. But for now, "we have recruited a first group of 50 volunteers on our site who will receive the vaccine and then there will be 50 new arrivals, before ramping up," said Lee Fairlie. This is much less than in the United Kingdom where the test already involves 4,000 people and "should provide the first information on the immune response in the coming weeks," added the South African pediatrician.

The volunteers selected in South Africa are "all between 18 and 65 years old and we made sure that they were in good health and did not suffer from chronic diseases requiring special medical attention," said Lee Fairlie. She recognizes, however, that the trial could be extended to less healthy people, "depending on what we will learn about the safety of the vaccine after the first tests."

The importance of a clinical trial on the African continent

As the World Health Organization (WHO) insists on the need to make a future Covid-19 vaccine accessible to everyone, the clinical trial in South Africa may prove crucial. Tests carried out in a country or only a continent are not sufficient to prove the effectiveness of a vaccine because "certain populations can sometimes have different immune reactions", notes Éric D'Ortenzio, epidemiologist at Inserm, contacted by France 24. "Genetically speaking, we have a very diverse population in South Africa and different from that of the United Kingdom or Brazil, which is why it is important to conduct tests here", specifies Lee Fairlie. She believes that the South African trial will allow to judge the effectiveness of the vaccine for the whole continent, "although it would always be better to conduct additional studies in other countries".

South Africa also presents a very different health environment from a European or South American country, which makes the results of this clinical trial interesting. "There is a prevalence of very specific diseases here, such as tuberculosis and the HIV virus. And it will be necessary to understand how people affected react to a vaccine," notes Lee Fairlie.

This is particularly true for AIDS, "an important issue in South Africa where nearly 7.5 million people have been infected with the virus", recalls the South African scientist. She hopes, moreover, to be able to include individuals with HIV in a group of volunteers "if we can establish that there is no risk associated with taking the vaccine for this population". In this regard, this clinical trial can, beyond South Africa and the continent, prove to be rich in lessons for the whole world. One of the central questions in the search for treatments for Covid-19 concerns how people with weakened immune systems due to diseases like the AIDS virus could react to a future vaccine.

Testing in Africa, still a sensitive issue

The importance of this first clinical trial in Africa is also due to the very controversial history of vaccine tests carried out on the continent. Large pharmaceutical groups have been accused, like Pfizer in 1996, of having taken advantage of the lack of information from local populations to conduct tests under questionable conditions.

The violent reaction to the statements of a French doctor who had called, in April, to test vaccines in Africa shows how much these scandals have left traces. "The doctor's remarks were rash, and had potentially racist overtones," said Lee Fairlie.

The experts interviewed by France 24 all recognize that there is work to be done to restore confidence in local populations in clinical vaccine trials. "The key is that people are properly informed about the tests and that, through awareness campaigns, we can get people involved, that is to say that they really want to participate", underlines Éric D'Ortenzio. Lee Fairlie hopes that the trial of the ChAdOx1 nCoV-19 vaccine, which adheres to international rules on obtaining informed consent, will help "allay the fears that some may still have".

Of course, scientists hope the Oxford vaccine fulfills its promise. But if, at a minimum, the tests carried out in South Africa made it possible to erase the legacy of the past, it would already be a victory.

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