Seasonal theory of COVID-19; one-year observation

Abstract

Objectives: SARS-CoV-2 infected over 100 million individuals worldwide during one year interval. With the increase in the number of cases and deaths, theories were adopted; one important theory was the seasonality of COVID-19. This study aimed to show the potential seasonality of SARS-CoV-2 over a period of one year (one winter/summer and one transition (spring/autumn) season). Methods: Data about the global incidence of the cases of one year interval and the doubling and halving time of cases for 10 countries were obtained from COVID intel Database, WHO website. Results: A peak in the number of COVID-19 cases and deaths during late autumn and winter months were observed along with some decrease in the number of cases and deaths during spring and summer. The average of doubling and halving time for the chosen countries varied across the sphere; the average doubling and halving time for (N°) countries were (264.14) and (52.64), respectively, while for (S°) countries were (20.91) and (148.40), respectively. Conclusion: The epidemiological triad, (virus longevity in the air and on surfaces, increased susceptibility of the human victim in cold and dry weather and changes in human social behavior between winter and summer), explains the seasonal changes of the SARS-CoV-2 characteristics. So far the data for SARS-CoV-2 lie on the same line for the seasonality theory as other viruses such as influenza and SARS-CoV, follow the seasonality theory (they slow down during the summer and rise during winter), yet, longer periods of observation are required to confirm this theory.