COVID-19 epidemic scenarios into 2021 based on observed key superspreading events

Key high transmission dates for the year 2020 are used to create scenarios of the evolution of the COVID-19 pandemic in several states of Mexico for 2021. These scenarios are obtained through the estimation of a time-dependent contact rate, where the main assumption is that disease behavior is heavily determined by the mobility and social activity of the population during holidays and other important calendar dates. First, changes in the effective contact rate on predetermined dates of 2020 are estimated. Then, this information is used to propose different scenarios for the number of cases and deaths for 2021. The fundamental assumptions behind this methodology are that the effective contact rate incorporates the main superspreading transmission events during last year, that each region has an independent epidemic not explicitly interconnected with other regions and, finally, that there are no new highly transmissible SARS-CoV-2 variants active during the timeline of the forecasts. Also, several levels of vaccination are considered to analyze their impact on the projections of the epidemic curve. The objective is to generate a range of scenarios that could be useful to evaluate the possible evolution of the epidemic and its likely impact on incidence and mortality.