The first three months of the COVID-19 epidemic: Epidemiological evidence for two separate strains of SARS-CoV-2 viruses spreading and implications for prevention strategies

Knut M. Wittkowski

is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10. 1101 A major problem with respiratory diseases is that one cannot stop all chains of infections within families, friends, neighbors, … . Even after a couple of weeks of "lockdown" there will be a few infectious persons, and as long as there are enough susceptible people in the society, this is enough to re-start the epidemic until there are enough immune people in the society to create "herd immunity". Hence, one would expect the cases to appear in waves (Fig 15, the period of the "lockdown" corresponds to March to May, 2020 in the U.S.). Such waves of cases have been seen in different countries and the longer than expected duration of the epidemic supports the hypothesis that the social distancing / lockdown interventions had some effect, albeit at a high cost for approx. 10% of deaths saved.