Modeling COVID-19 dynamics in the Basque Country: characterizing population immunity profile from 2020 to 2022

Area of Science:

• Epidemiology
• Immunology
• Mathematical Modeling

Background:

• COVID-19 (caused by SARS-CoV-2) poses a global health challenge.
• Vaccination is key to reducing severe disease, but waning immunity and variants necessitate ongoing efforts, including boosters.
• This study models COVID-19 dynamics in the Basque Country (2020-2022) to understand population immunity and outbreak severity.

Purpose of the Study:

• To characterize the population's immunity profile against COVID-19.
• To assess the impact of immunity on COVID-19 outbreak severity in the Basque Country.
• To analyze the dynamics of virus-specific and vaccine-induced immunity over time.

Main Methods:

• Developed a SIR/DS model incorporating three immunity levels and boosting effects from reinfection/vaccination.
• Validated the model using empirical daily case data from the Basque Country.
• Tracked shifts in immunity status and their effects on disease dynamics.

Main Results:

• The epidemic showed three phases: initial surge, intermediate outbreaks (Alpha/Delta variants), and Omicron-dominated phase.
• Reinfection rates reached $$ and seroprevalence peaked at $$ during the intermediate and Omicron phases, respectively.
• Naive/unvaccinated individuals significantly contributed to outbreak severity, especially during the Omicron wave.

Conclusions:

• Continuous monitoring and adaptive strategies are vital for managing COVID-19's evolving landscape.
• Dynamic interactions between immunity, reinfection, and vaccination critically shape outbreak severity.
• Findings guide evidence-based interventions for mitigating COVID-19 impact.