We compute the factor R 0 (t) by using the SIR model in Italy and its some regional countries in the period April May 2020. We find that it is descending to a minimum value of 0.22 in Italy and respectively of 0.10,0.15 ,and 0.07 for each region respectively
Estimation of the R0 factor of the SIR Model in Italy and some its regions as consequence of the pandemic Sars-Covid-2