Models for COVID-19 Daily Confirmed Cases in Different Countries

In this paper daily confirmed cases of COVID -19 in different countries are modelled using different mathematical regression models. The mathematical curve fitting is used as a prediction tool to model both pervious and next upcoming Coronavirus waves. The used models cover virus spreading from 1/3/2020 to 10/4/2021. According to virus spreading, countries under study in this paper are categorized into three main categories. First category in which Coronavirus first wave takes about two year seasons (about 180 days) to make a complete virus cycle. Second category is countries with higher transmission rates with one year season (about 90 days) to make the first complete virus cycle. These countries take offline periods with low spreading rates. The third category is countries with the highest transmission rates and make complete virus cycles without offline periods. All categories are modelled with different mathematical fitting models. Finally, predictions of different upcoming scenarios for these countries are made.Funding Statement: The research is partially supported by P.R.I.N. 2019 and the RUDN University Program 5-100".Declaration of Interests: The authors have no competing interests.