Transmission Dynamics of COVID-19 and Impact on Public Health Policy

B Shayak; Mohit Manoj Sharma; Richard H Rand; Awadhesh Kumar Singh; Anoop Misra

We can see that the model is not only a good fit to the peak phase of the epidemic but it also correctly predicts the slow yet persistent linear growth in cases after the peak. We further see that the effective x (0) is about 13000, implying that approximately 2/3 of the originally susceptible people have been affected. This fraction is similar to the predictions commonly made with respect to the spread of the virus in free society if steps are not taken to reduce social contacts. We again note however, that a fit of the model to data from an entire country is heuristic at best on account of the huge spatial variation of the infection rate, and the model's assumption of homogeneous mixing among the population. In actual practice, it will be much more useful an exercise to attempt fitting the data to the statistics of a city, district or county, where there is more uniform mixing among the entire population. In such a case, x (0) will also not be a completely unknown quantity but will start from a reasonably well-known figure.