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 relevant SARS-CoV-2 variants up to November 2021 was about 44. Moreover, the number of new relevant variants per ten million cases turned out to be 1.64 in November 2021, slightly decreased in comparison to the value of 2.29 in March 2020. Conclusions: Our simple mathematical model can evaluate the number of relevant SARS-CoV-2 variants as the cumulative number of cases increase worldwide and may represent a useful tool in planning strategies to effectively contrast the pandemic.
How many relevant SARS-CoV-2 variants might we expect in the future?