Detection of covid-19 epidemic waves and their interrelationships in the tri-border region between Brazil, Paraguay, and Argentina, 2020-2023: Covid-19 epidemic waves in the tri-border region

Introduction: The COVID-19 pandemic, caused by the SARS-CoV-2 virus, was declared a global public health emergency in 2020, profoundly impacting countries around the world. International border regions, such as the tri-border region between Brazil, Paraguay, and Argentina, faced unique challenges, such as high population mobility and the lack of regional integration in controlling the pandemic. Thus, this study aimed to identify and characterize the epidemic waves of COVID-19 in the three health regions of this tri-border region between 2020 and 2023. Methods: Using secondary epidemiological data, confirmed cases of COVID-19 were analyzed in 9 municipalities in Brazil, 22 in Paraguay, and 13 in Argentina.  Were used to smooth the epidemic curves and identify the waves, their peaks, and valleys based on the EpidemicKabu library, and the cross-correlation statistic function of the epidemic waves in the historical series of the countries. Results: The study revealed five epidemic waves in total, five in Brazil, five in Paraguay and two in Argentina. The relation between the epidemic waves in Brazil and Paraguay was 0.74 and a lag -1, the correlation between Brazil and Argentina was 0.69 and lag max in 0 and the cross-correlation between Paraguay and Argentina resulted in 0.80 and lag max in 0, a strong correlation was observed of the three regions. Conclusions: The results highlight the temporal heterogeneity of epidemic waves across the three countries and the importance of cross-border cooperation for infectious disease control. The study reinforces the need for integrated health policies and coordinated epidemiological surveillance in border regions, especially in areas with intense population mobility.