Time series analysis and seasonality trends of SARS-CoV-2 in Ecuador (2020-2024): a four-year study.

INTRODUCTION

Since the appearance of SARS-CoV-2 in 2019, the virus has been characterized by rapid spread and has generated multiple variants, creating ongoing challenges to healthcare systems worldwide. In Ecuador, reported COVID-19 cases declined steadily after 2022, falling from 10,677 cases in 2022 to 1,910 in 2023 and 720 in 2024. Reported deaths also decreased sharply, limited to 30 reported deaths in 2024, mainly reflecting the impact of vaccination programs. Although the WHO has declared that COVID-19 is no longer a global pandemic, it remains a public health concern requiring ongoing surveillance. Understanding whether SARS-CoV-2 is transitioning toward a seasonal endemic pattern remains complex, given its evolutionary dynamics, diverse clinical forms, and population-level factors. This study aimed to forecast seasonal trends and potential endemicity of SARS-CoV-2 in Ecuador using reported surveillance data from 2020 to 2024.

METHODS

A time series analysis was conducted using the endemic channel approach with ARIMA (p, d, q)(P, D, Q)[m] modeling, based on data from the Ecuadorian Ministry of Public Health.

RESULTS

The results showed an upward trend peaking in 2022, followed by stabilization in 2024. Consistent seasonal peaks occurred at the beginning of each year, followed by a gradual decline throughout the year. The ARIMA (0,2,1)(0,0,1)[52] model, validated through white noise tests, generated forecasts indicating a continued decline in case numbers.

DISCUSSION: These findings suggest that SARS-CoV-2 in Ecuador is adopting a secular, seasonal transmission pattern, potentially moderated by vaccination coverage.