Application of the Fluctuation Test to the data of Morbidity and Mortality by COVID-19 in China 2020-2023

In this work the Luria and Delbruck Fluctuation Test was applied to the data of Morbidity and Mortality by COVID-19 in China from January 2020 to August 2023. Three types of data were used: es.statista.com, datosmacro.expansion.com and larepublica.co without modification, but trying to avoid and justify the anomalies and inconsistencies observed. The methods originally used to establish the interactions of two populations were evaluated: the viral population with that of its host and the drift of both organisms. Only the fluctuations of the weekly Variance of daily increase of Cases (Morbidity) and of the weekly Variance of daily increase of Deaths (Mortality) were studied. The results showed that the Fluctuation Test is applicable to the selected data from China and other data from India, Japan and South Korea, used as controls. The study was separated into two periods: a first initial period from January 2020 to September 2021 and a second final period from October 2021 to August 2023. Results were obtained for Morbidity and Mortality that relate the fluctuations of the first with the fluctuations of the second. However, it was possible to detect some anomalies and uncertainties that were possibly derived from inconsistencies in the original data. A repeated fluctuation was observed in the boreal winter in January, February and March of each one of the year studied. A clear decrease in fluctuation was detected in that period in 2021 that could be attributed to the strict confinement during the quarantine in China between 2020 and 2021. Massive, extensive and intensive vaccinations failed to completely eliminate the most important fluctuations. In this work we tried to correlate the appearance of some virus variants with the fluctuations. The most relevant results of said correlation are presented. With the results of this work, the animal origin cannot be confirmed nor can the human or laboratory origin of the SARS CoV-2 virus that caused the initial emerging infection, be ruled out. However, it was concluded that this method could be used to search for clues about its origin. One of these keys is the comparison of the result of the first important fluctuation in the boreal winter of 2020 in each of the countries studied as controls: India, Japan and South Korea. The comparison of this result with the first fluctuation of China for that same period could give clues about the origin of the virus.