How many relevant SARS-CoV-2 variants might we expect in the future?

A bstract Objectives The emergence of new SARS-CoV-2 variants is a major challenge in the management of Covid-19 pandemic. A crucial issue is to quantify the number of variants which may represent a potential risk for public health in the future. Methods We fitted the data on the most relevant SARS-CoV-2 variants recorded by the World Health Organization (WHO). The function exploited for the fit is related to the total number of infected subjects in the world since the start of the epidemic. Results We found that the number of new relevant variants per ten million cases diminished by 30.4% between March 2020 and March 2022 (from 1.25 to 0.87). However, the decrease is now very slow and a further reduction by 10% would happen only for 5.6 billion infections in the world, i.e. ten times the cases from the beginning of the epidemic up to June 2022. Conclusion Our simple mathematical model can provide an estimate of the number of relevant SARS-CoV-2 variants as the cumulative number of cases increases worldwide and may represent a useful tool in planning strategies to effectively contrast the pandemic.