Since 31 December 2019, when China informed the WHO of an epidemic of respiratory infection due to a new coronavirus, we have experienced an unprecedented succession of “firsts”. The slow-motion explosion, over several weeks, initially of a regional, and then of a global pandemic, viewed in real time by public and scientists alike, in ever greater transparency (thanks to open data); the collective fear, coupled with inability to take its measure, face to overwhelmed health systems in Wuhan, in Lombardy, in the Haut-Rhin, in New York; the unprecedented implementation of containment policies in many countries; the emergence of medical populism advocating therapeutic schemes not validated by any data, yet supported by many political leaders; the organisation in record time of therapeutic clinical trials, all or almost all of which were negative regarding antivirals for nearly-two years; the progressive understanding of a new pathology, a delayed inflammatory, post-viral lung disease, accessible to immunomodulatory treatments; and, finally, the development in unprecedented time of effective vaccines, which became the first lever of action and the key to a gradual exit from the crisis.
Analyses drawn from previous epidemics (Spanish flu or HIV in particular) impeded understanding of the differing issues surrounding Covid-19 and its vaccines. These are but some of the issues addressed by the February 2022 symposium, of which the articles in this special edition constitute a report. The complex interplay of variant emergence, the resulting partial immune escape, and the efforts made to anticipate their evolution; the impact of booster shots in a country that is a pioneer not only in the deployment of SARS-CoV-2 vaccines, but also in the real-time collection, analysis and publication of data, Israel; the long-term impact of the immunization programs initiated in 2021; the efforts made in pharmacovigilance to monitor as closely as possible the events associated with unprecedentedly large-scale campaigns; the use of various vaccines for different stages of the vaccination schedule, rendered all but unavoidable by the diversity of available products; the pros and cons of vaccinating children under the age of 12, and the individual and community benefits to be expected; the use in immunocompromised patients of palliatives to vaccination, via passive immunotherapy; the distrust exhibited towards these new vaccines, its origin, its defining features, its connections with negative feelings leading in some cases to conspiracy theories, and also with the medical populism mentioned above; the disparate aspects of vaccination promotion, which has occasionally reproduced the inequalities associated with severe forms of the infection… All of these themes have remained highly topical in 2021 and 2022; understanding them helps us to foresee what the next two years will be like; this retrospective review also provides us with perspectives on how, in the event of a future pandemic, our medical and societal response could improve.
Thanks again to all the speakers who, with clarity, humility and conviction, have rendered more understandable the enormous volume of scientific data to which the pandemic has given rise.