Emergence of novel SARS-CoV-2 variants keeps slowing down

Background Although COVID-19 pandemic has no longer been classified as an international public health emergency of concern after May 2023, multiple variants with different characteristics keep emerging. Given the complex spatial-temporal characteristics of epidemics, responding to potential changes in variants is a significant public health challenge. Serotypes are defined as unique variants within specific immune response characteristics, which are used in the study of various pathogens. The sero-epidemiological features of COVID-19 may offer new insight into public health. Methods Based on the global SARS-CoV-2 genome deposition data in Our World in Data (OWID) based on GISAID from March 1, 2021 to May 3, 2024, we analyzed the epidemic features of different variants based on the serotype concept and combined with cross-sectional studies. Results In the dataset comprising variants from 58 countries or regions with complete information, we calculated the median duration times of epidemic, the median epidemic peak times for Serotypes Ⅱ-Ⅴ and the median alternation times of epidemic for Serotypes I-Ⅱ to Ⅴ-Ⅵ respectively. There are linear relationships for these time period between the epidemics of Serotypes Ⅱ, Ⅲ, Ⅳ and Ⅴ, except the longer duration time for Serotype I. By constructing a simple linear regression and curve regression equation, the emerging of a new serotype can be predicted with the time around 2025, or even later. Conclusion The gradually-increased prevalence periods for SARS-CoV-2 serotypes except Serotype I may suggest a slowing down mutation rate. Understanding the epidemic time of different serotypes can provide insight into the surveillance and forecasting of COVID-19.