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The United Nations did not recommend mask wearing for the overall population before June 2020. There were insufficient clinical trials in real-world conditions to prove their usefulness, and reservations were expressed over counter-productive behaviour that a “false feeling of security” might provoke. But today, in poorer countries that lack access to anti-COVID-19 vaccines, this type […]

In the fight against COVID-19, public health officials rely on surveillance data that is either collected physically (during a visit to the doctor, for example) or through on-line surveys. Small-scale studies carry the risk of targeting an unrepresentative sample of the population, while large-scale surveillance is potentially more useful, since it enables, through specific statistical […]

The emergence of Variants of Concern (VOCs) with increased transmissibility and capable of escaping immunity has called into question the efficacy of current vaccines. Several studies have shown that these variants’ new capacities involve mutations in the spike protein that controls entry of the virus into cells. The Omicron variant, recently identified in South Africa, […]

The COVID-19 pandemic is still not over and SARS-CoV-2 continues to evolve. Firstly detected in November 2021 in Botswana and in South Africa, the Omicron (B.1.1.529) variant of concern (VOC) is supplanting the Delta variant and becoming dominant. Its doubling time may be between 1.2 and 3.6 days in an immunized population. It carries more […]

Innate antiviral immune responses, located upstream to antibody and cellular responses, impose selection pressure during SARS-CoV-2 infection and directly impact the severity of COVID-19. In infected cells, the RIG-I and MDA-5 pathways detect the presence of viral RNA and activate certain defence mechanisms. But some data suggests that SARS-CoV-2 could be capable of blocking these […]

The vaccines now available against COVID-19 were created using the spike surface viral protein from the original Wuhan strain. The new Omicron variant carries a much higher number of mutations than other variants, especially in the S protein. There are therefore grounds to fear that it can escape antibodies produced by current vaccines. In this […]

Massive vaccination campaigns began at the end of 2020. They enabled numbers of people affected by severe forms of COVID-19 to be reduced. But during the summer, the Delta (Indian) variant emerged, more transmissible than the Alpha (UK) variant, and became dominant. At that time, only a small proportion of the populations of developed countries […]