Projecting the SARS-CoV-2 transition from pandemicity to endemicity: Epidemiological and immunological considerations

Abstract

In this review, we discuss the epidemiological dynamics of different viral infections to project how the transition from a pandemic to endemic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) might take shape. Drawing from theories of disease invasion and transmission dynamics, waning immunity in the face of viral evolution and antigenic drift, and empirical data from influenza, dengue, and seasonal coronaviruses, we discuss the putative periodicity, severity, and age dynamics of SARS-CoV-2 as it becomes endemic. We review recent studies on SARS-CoV-2 epidemiology, immunology, and evolution that are particularly useful in projecting the transition to endemicity and highlight gaps that warrant further research.

Fig 1. Waves of influenza A/H1N1 and COVID-19 during initial invasion and subsequent circulation.

Data sources: (A) Olson and colleagues [24]; (B) Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD) [25]; (C) Ritchie and colleagues [6]. Coronavirus Disease 2019, COVID-19; Severe Acute Respiratory Syndrome Coronavirus 2, SARS-CoV-2.

Fig 2. Changing age distributions of influenza A/H1N1, dengue, and COVID-19 during the transition from pandemic to endemic.

Data sources: (A) Olson and colleagues [24]; (B) Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD) [25]; (C) Karyanti and colleagues [38]; (D) Centers for Disease Control and Prevention [128]. Coronavirus Disease 2019, COVID-19.

Fig 3. Detection of seasonal coronaviruses in 2 cohort studies, broken down by strain and age group.

Data sources: (A) Nickbakhsh and colleagues [61]; (B) Monto and colleagues [60]. HIVE, Household Influenza Vaccine Evaluation.