Fit this SIR model to the data to learn something about the longevity of the immunity to SARS-CoV-2. They also present data on the percentage of seroconverted individuals

Theory predicts that selection for pathogen virulence and horizontal transmission is highest at the onset of an epidemic but decreases thereafter, as the epidemic depletes the pool of susceptible hosts. We tested this prediction by tracking the competition between the latent bacteriophage l and its virulent mutant lcI857 throughout experimental epidemics taking place in continuous cultures of Escherichia coli. As expected, the virulent lcI857 is strongly favored in the early stage of the epidemic, but loses competition with the latent virus as prevalence increases. We show that the observed transient selection for virulence and horizontal transmission can be fully explained within the framework of evolutionary epidemiology theory. This experimental validation of our predictions is a key step towards a predictive theory for the evolution of virulence in emerging infectious diseases. Citation: Berngruber TW, Froissart R, Choisy M, Gandon S (2013) Evolution of Virulence in Emerging Epidemics. PLoS Pathog 9(3): e1003209. doi:10.1371/ journal.ppat.1003209 Editor: François Balloux, University College London, United Kingdom Received July 25, 2012; Accepted January 9, 2013; Published March 14, 2013 Copyright: ! 2013 Berngruber et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The work was funded by the ANR grant EPICE 07 JCJC 0128, and the ERC grant EVOLEPID 243054 to SG. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: berngruber@gmail.com