https://doi.org/10.1140/epjp/s13360-021-01339-6
Regular Article
A simplified estimate of the effective reproduction number 
using its relation with the doubling time and application to Italian COVID-19 data
1
Università Politecnica delle Marche, Ancona, Italy
2
INFN Sezione di Bologna, Bologna, Italy
3
Università degli Studi di Napoli Federico II, Naples, Italy
4
INFN Sezione di Napoli, Naples, Italy
5
INFN Sezione di Milano Bicocca, Milano, Italy
6
INFN Sezione di Padova, Padova, Italy
7
Alma Mater Studiorum Università di Bologna, Bologna, Italy
Received:
15
December
2020
Accepted:
23
March
2021
Published online:
11
April
2021
A simplified method to compute , the effective reproduction number, is presented. The method relates the value of to the estimation of the doubling time performed with a local exponential fit. The condition 
corresponds to a growth rate equal to zero or equivalently an infinite doubling time. Different assumptions on the probability distribution of the generation time are considered. A simple analytical solution is presented in case the generation time follows a gamma distribution.
© The Author(s) 2021
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
