Why 18 months before a COVID-19 vaccine?

COVID-19 raises a lot of questions among our readers. We invite you to send them to our journalist Jean-François Cliche (jfcliche@lesoleil.com) and he will respond to one a day in the coming weeks.
Q “I find it very good that the Quebec Medicago company plans to be able to produce a vaccine within 12 to 18 months instead of several years. However, and even if I understand that there are several stages to be crossed, would it not be possible to think of an even faster procedure given the importance of the threat of the new coronavirus? ” asked Marius Demers of Quebec.

A There is a fundamental rule in medicine which is so ancient that, even today, we still often see it passing in Latin: primum non nocere, deinde curare , “first do no harm, then treat”. And in a way, it is to comply with it that not only vaccines, but also all drugs, must go through the same steps to ensure: 1) that they are not harmful and 2 ) that they are effective.

We start with “preclinical tests” on animals, to see if the treatment has negative effects on mammals (like us). Next come three phases of “clinical trials” in humans. In a first phase, the treatment is administered (in small doses first, then ascending) to healthy adults to see if it is safe. In phase 2, we try to see if the treatment can have any effectiveness. Then if it turns out that the vaccine / drug seems to work, phase 3 refines our knowledge by determining if this effect can be useful in a clinical context.

There is currently a lot of pressure on researchers and regulators around the world to speed up this process, which typically takes several years, to get a COVID-19 vaccine out as quickly as possible. Medicago says it is ready to start preclinical tests now, and an American team announced this week that, thanks to previous work on other coronaviruses (SARS 2002 and MERS 2012), it will launch this spring phase 1 trials for a human vaccine.

But this eagerness, understandable as it is, creates some discomfort among scientists. Last Monday, on the site of Nature , the virologist of the University Fudan (Shanghai) Shibo Jiang warned of the dangers that there are to take short cuts with the clinical trials and even preclinical. “It’s not a waste of time,” he writes. Studies with SARS have shown disturbing immune responses in ferrets and macaques, but not in mice. Similarly, some protein fragments [note: some vaccines are based on proteins or protein fragments] may cause a weaker or safer response than others, so the sensible thing to do is to study them in the animal before human being. ”

In addition, there are known examples of vaccine trials that have gone rather wrong – as in 1966, when studies on a vaccine against respiratory syncytial virus (a form of the common cold) led to its discontinuation because some of the children vaccinated not only were they not immune, but they contracted the virus more and made a more severe form of the disease . So even if it is necessary to act as quickly as possible to “get out” a vaccine and / or treatments against COVID-19, most scientists speak of a horizon of about 18 months because they know that it Also, keep in mind that the regulatory steps in place exist for good reasons.

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