Vladimir Putin’s announcement on Tuesday, August 11, of the development of a vaccine against the coronavirus immediately aroused reservations and even concerns among scientific experts interviewed by Reuters. This announcement confirms that the global vaccine race is on. While the epidemic has already caused the death of more than 730,000 people worldwide, the immunization of the population against SARS-CoV-2 seems to be one of the only ways out of the crisis.
To date, there are some two hundred candidate vaccines. “Some governments have already acquired or reserved vaccines that could be administered at the end of the year”, explains Marie-Paule Kieny, director of research at Inserm, former director general at the World Health Organization (WHO), who chairs the new “Covid-19 vaccine committee”, which issued an opinion on the subject a month ago. “It is imperative to give ourselves the time necessary for a rigorous evaluation, both of the efficacy and of the safety of candidate vaccines before their large-scale use”, clarified this opinion. The development of a vaccine obeys very strict rules.
How do Covid-19 vaccine candidates work?
” At this stage, insists Marie-Paule Kieny, we know little about the goal of vaccine candidates: to protect against infection or decrease the severity of the disease. “ Almost all of the candidate vaccines target the Spike protein, the key that allows SARS-CoV-2 to enter cells. Schematically, this antigen is presented to the immune system to force the latter to counter-attack thanks to various defense mechanisms. This response to a fictitious attack should allow the body to protect itself during its first “real” encounter with the virus.
What are the different steps to develop a vaccine?
Once a vaccine candidate has been developed, it must go through several stages, starting with preclinical trials (on animals). “This is an essential step to select the best candidates and avoid administering to humans vaccines that are ineffective or that would be too inflammatory. These tests can often give excellent results in animals, but not necessarily then in humans ”, specifies the Infovac website.
Then clinical trials in humans are conducted in four phases. Those of phase 1 generally take place on a few dozen people. They are intended to observe the possible very frequent side effects (by comparing with a placebo or a known vaccine). They also make it possible to determine the best dose to inoculate, by measuring the antibodies produced by healthy volunteers, continues the site of experts specializing in vaccination, Infovac. “Side effects have thus been noted on these vaccines such as fever”, said Professor Patrick Berche, member of the Academy of Medicine, on BFM.
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