My blog on the spread of Covid-19

Article: Regional analysis of COVID-19 in France from fit of hospital data with different evolutionary models (13 May 2020, version 4: 17 June 2020);
Abstract (Résumé en français):
The SIR evolutionary model predicts too sharp a decrease of the fractions of people infected with COVID-19 in France after the start of the national lockdown, compared to what is observed. I fit the daily hospital data: arrivals in regular and critical care units, releases and deaths, using extended SEIR models. These involve ratios of evolutionary timescales to branching fractions, assumed uniform throughout a country, and the basic reproduction number, R0, before and during the national lockdown, for each region of France. The joint-region Bayesian analysis allows precise evaluations of the time/fraction ratios and prehospitalized fractions. The hospital data are well fit by the models, except the arrivals in critical care, which decrease faster than predicted, indicating better treatment over time. Averaged over France, the analysis yields R0 = 3.4±0.1 before the lockdown and 0.65±0.04 (90% c.l.) during the lockdown, with small regional variations. On 11 May 2020, the Infection Fatality Rate in France was 4 ± 1% (90% c.l.), while the Feverish vastly outnumber the Asymptomatic, contrary to the early phases. Without the lockdown nor social distancing, over 2 million deaths from COVID-19 would have occurred throughout y France, while a lockdown that would have been enforced 10 days earlier would have led to less than 1000 deaths. The fraction of immunized people reached a plateau below 1% throughout France (3% in Paris) by late April 2020 (95% c.l.), suggesting a lack of herd immunity. The widespread availability of face masks on 11 May, when the lockdown was partially lifted, should keep R0 below unity if at least 46% of the population wear them outside their home. Otherwise, without enhanced other social distancing, a second wave is inevitable and cause the number of deaths to triple between early May and October (if R0 = 1.2) or even late June (if R0 = 2).
Press release: Une nouvelle analyse régionale du COVID-19 en France
Presentation: Analysis of French COVID-19 hospital data with a SEAFHCDRO model (5 May 2020, Institut d'Astrophysique de Paris)

My thoughts on the spread of the pandemic A few things to know about the spread of COVID-19 (revised version of 2 April 2020)

Article in The Conversation (1 April 2020, in French, by André Klarsfeld, with charts from myself) Pour comprendre la pandémie, les courbes valent mieux que les avalanches de chiffres. Reproduced in weekly magazine La Tribune and monthly Santé Magazine.

Useful links:

Progression in France


Analysis: Progression in different countries: (until 18 June 2020).

Total cumulative cases

New cases

Fraction of population having caught infection

Fraction of population having caught infection (time aligned)

Doubling time of total cases

Doubling time of total cases (aligned by time)

Total deaths

New deaths

Fraction of deceased population

Fraction of deceased population (aligned by time)

Doubling time of total deaths

TotalFatality rate

Gary Mamon, e-mail: