COVID-19 vaccines: Frequently asked questions and updated answers.

At the end of December 2019, China notified the World Health Organization about a viral pneumonia epidemic soon to be named COVID-19, of which the infectious agent, SARS-CoV-2, was rapidly identified. Less than one year later, published phase 3 clinical trials underlined the effectiveness of vaccines utilizing hitherto unusual technology consisting in injection of the messenger RNA (m-RNA) of a viral protein. In the meantime, numerous clinical trials had failed to identify a maximally effective antiviral treatment, and mass vaccination came to be considered as the strategy most likely to put an end to the pandemic. The objective of this text is to address and hopefully answer the questions being put forward by healthcare professionals on the different anti-SARS-CoV-2 vaccines as regards their development, their modes of action, their effectiveness, their limits, and their utilization in different situations; we are proposing a report on both today's state of knowledge, and the 14 February 2021 recommendations of the French health authorities.