A retrospective analysis of COVID-19 dynamics in Mexico and Peru: Studying hypothetical changes in the contact rate

The COVID-19 pandemic has left many open questions for decision-makers. One of them is knowing the counter-factual effect that the implementation of different mitigation strategies to the ones actually used could have caused. This knowledge would allow to contemplate alternative strategies to deal with future infectious disease emergency. Motivated by the above, we model the observed COVID-19 dynamics for Mexico and Peru and explore the impact of implementing hypothetical stricter mitigation strategies on key days of civic, religious, or political character, that could alter contact and transmission intensities. We explore this impact through hypothetical contact rate reductions during the first year of the pandemic but at different times: i) near its beginning, ii) at the beginning of the second outbreak, and iii) end of the year. The effects of interventions are different for Mexico and Peru, but, in general, they do reduce the cumulative number of cases and deaths. Nonetheless, this study underlines the fact that the time and duration of interventions are important factors to obtain better reductions in prevalence. We also provide evidence that key calendar days are good change points for contact rates and, therefore, may be useful to define strategic time periods for effective interventions, particularly in countries with low testing and lack of contact tracing. We recreate different outbreaks of the COVID-19 disease dynamics in Mexico and Peru and explore the impact of hypothetical interventions that further reduce the contact rate.