Au-delà de la question "d'où sort le chiffre", je crois que ce serait encore plus intéressant de savoir comment il est calculé ! Parce que si l'on dit que l'évolution de l'indicateur "nombre de personnes contaminées" n'est pas pertinent au vu des variations dans la politique de test et dépistage, on peut se demander quelle est la barre d'erreur sur le R0...
Et bien ce n'est pas inintéressant, on en apprend un peu plus
ici:
As of 14 April 2020, there had been 71,903 incident hospitalizations due to SARS-CoV-2 reported in France and 10,129 deaths in hospitals, with the east of the country and the capital, Paris, particularly affected (Figure 1A-B). The mean age of hospitalized patients was 68y and the mean age of the deceased was 79y with 50.0% of hospitalizations occurring in individuals >70y and 81.6% of deaths within that age bracket; 56.2% of hospitalizations and 60.3% of deaths were male (Figures 1C-E). Hospitalization and death data only capture the most severe infections. To reconstruct the dynamics of all infections, including mild ones, we jointly analyze them with data documenting the risk of death among persons infected by SARS-CoV-2 coming from a detailed investigation of an outbreak aboard the Princess Diamond cruise ship where all passengers were subsequently tested (719 infections and 13 deaths). By coupling the French passive surveillance hospital data with the active surveillance performed aboard the Princess Diamond, we can disentangle the risk of being hospitalized in those infected from the underlying probability of infection (4–6).
Une nouvelle fois, le Diamond Princess à la rescousse ! Mais attention à la puissance statistique de tout cela, certains groupes d'âge sur ce bateau devaient manquer un peu de sujets...
D'autant plus que les références 4-6 sont citées de manière un peu abusives pour certaines - hé oui, c'est une pré-publication ici aussi.