2020, Paper, "We provide an elementary mathematical description of the spread of the coronavirus.  We explain two fundamental relationships:  How the rate of growth in new infections is determined by the “effective reproductive number”; and how the effective reproductive number is affected by social distancing.  By making a key approximation, we are able to formulate these relationships very simply and thereby avoid complicated mathematics.  Consequently, our description requires no more than basic high-school algebra."
Non-HKS Faculty Author Website - Elon Kohlberg