"The world now has no choice but to count on science."

Jacques Fellay (credit: Alain Herzog, EPFL) - Jacques Fellay, a professor at EPFL's School of Life Sciences, talks about mutations of the novel coronavirus, variants in the human genome, and how they might affect the current pandemic. Has the SARS-CoV-2 virus mutated by now? Like all viruses, SARS-CoV-2 evolves over time through random mutations of its genome (which is made of single-stranded RNA). These little changes can be used to draw up phylogenetic trees, a diagram that shows evolutionary relationships between coronaviruses, and can tell us about the virus's spread. However, most mutations have no impact on viral fitness and ability to cause disease, and so far, there is no evidence of more or less virulent strains of SARS-CoV-2. What did we learn from the genome of SARS-CoV-2? First, we very quickly learned that the pathogen causing a severe pneumonia of unknown origin in the city of Wuhan was in fact a coronavirus. Second, sequencing of the viral RNA made it possible to estimate that the virus probably jumped from animal to human in November 2019, and to identify the bat as the most likely reservoir - sorry to disappoint, but it's probably not the pangolin. Finally, the distribution of the random mutations detected in the virus's genome makes it possible to reconstruct the temporal and geographical routes of viral propagation, which is important for informing public health policy.