Coronavirus: the slow and difficult manufacture of a vaccine

Epidemiologists, virologists, public health experts, all agree: it is thanks to massive vaccination campaigns that we will be able to stop the SARS-Cov-2 pandemic.

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A challenge. “So far, no effective vaccine has been created against a human coronavirus”, virologist Christian Bréchot, former director of the National Institute of Health and Medical Research (Inserm), told AFP.

What are the current projects?

The sequencing of the genome of the new coronavirus in mid-January, then the worldwide spread of the disease, has boiled all that the planet has of vaccine research laboratories. The big names in pharmacy, assisted by a myriad of biotechnology laboratories, are in the ranks: more than 100 vaccine projects are currently under development.

The European Medicines Agency (EMA) indicates that it is in contact with those responsible for a “Dozen” vaccine projects, two of which are already in clinical trials. In France, the Institut Pasteur alone carries out three “Vaccine candidates” while China is conducting clinical trials for three potential vaccines head-on.

Pharmaceutical industry giants Sanofi of France and Britain’s GSK of Britain hope to jointly offer a vaccine by next year. Their American competitor Johnson & Johnson is betting on its own vaccine formula in early 2021.

What are the obstacles to overcome?

The development of a Covid-19 vaccine must first take into account the immune response in severe cases. How to stimulate the antiviral reaction with a vaccine without leading to a runaway of the immune machinery? “In this phenomenon, we have not yet fully understood the role played by antibodies, explains Frédéric Tangy, vaccine specialist at the Institut Pasteur. Under certain conditions, antibodies can make the disease worse. “

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Another difficulty, he says again: coronaviruses “Mutate a lot”, which makes it more difficult to develop a targeted vaccine. This is why the Institut Pasteur is also working on a “Universal coronavirus vaccine”, directed against proteins common to this family of viruses, explains the scientist.

Researchers also face a final complication: it is easier and more efficient to develop a vaccine and distribute it before an epidemic wave. Recruiting guinea pig subjects then becomes more difficult since it must be ensured that they do not or will not be infected, which would distort or complicate the interpretation of the results.

When will a vaccine be?

“Success in the fall is possible if everything goes to perfection”, told the British newspaper The Times, British vaccine specialist Sarah Gilbert, a professor at the University of Oxford and already engaged with her biotech Vaccitech in clinical trials.

At the Institut Pasteur, where the first tests will start in July, Frédéric Tangy also believes that a vaccine could arrive “In late fall or early winter”.

But the European Medicines Agency is more cautious: “The timetable for vaccine development is difficult to predict. Based on past experience, it could take at least a year before a vaccine is ready to be approved and available in sufficient quantity to allow widespread use. “

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