AbstractA contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is known as Coronavirus disease 2019 (Covid-19). It engendered the whole civilization within a couple of months over the globe since it was first detected in Wuhan, China in late December 2019. Variation of proliferation rates in different regions assume that climatic parameters might have a vital role in Covid-19 transmission. In this study, the correlation between Covid-19 proliferation with demographic parameter (population density), and weather parameters (temperature, humidity, precipitation, wind speed, and sunshine hour) were investigated separately within the first 60 days of Covid-19 cases. To obtain a precedent correlation, weather and infection-related data of eight different geographically coordinated regions such as Alberta (Canada), Barcelona (Spain), Dhaka (Bangladesh), Île-de-France (France), Lombardy (Italy), New York (USA), Rio de Janeiro (Brazil) and West Bengal (India) having the diversity of climates were considered. It was observed that less densely populated regions (New York, Lombardy, Barcelona) were even highly affected than the highly populated regions like Bangladesh, West Bengal. A negative correlation between total cases and temperature perhaps made this difference. The higher wind speed perhaps accountable for long distance viral transmission. The non-steady humidity tentatively makes the people vulnerable towards Covid-19 infections. Higher precipitation may positively affect viral infection. Sunshine along with the higher temperatures are suspected to impede the contagion by Covid-19. Consequently, peoples in the regions of lower temperatures, higher wind speed, and unstable humidity have higher risks of Covid-19 infection.Keywords: Covid-19; population; viral proliferation; weather parameters; contagion.Introduction Covid-19 is one of the most uttered word since the outbreak of a contagious disease proliferated from the virus called SARS-CoV-2 in late December 2019. It was first detected at Wuhan in the Hubei province of China in December 20191 23. The Covid-19 has been regarded as history broken contagious disease as no other viral disease proliferated across the globe in the history at the same time. Despite taking immediate cautions to stop proliferation of this virus, it has travelled almost all over the globe through human to human interactions and engendered a pandemic situation threatening the healthcare systems of many countries. This virus is proved to be a highly contagious and proliferated more rapidly compared to any the other viruses of the Corona virus family4. Scientists around the world believe that this virus is spreading from the droplets thrown by coughing or sneezing by the infected individuals. These droplets may survive in air and in different types of surfaces for several hours and can potentially affect even healthy peoples come in contact5. However, the survival of these viral droplets may depend on some weather parameters like; temperature, humidity, and wind speed and of combined effects6 7 8. At high temperature, the viral proliferation may significantly be impeded as it deactivates the pathogen by decomposing the protecting protein layer9. Humidity can also be an integrated factor with wind speed as the droplets may survive extensive amount of time in dry, cold air and along with high speed wind that will cause faster transmission comparing to no humid areas10.Meanwhile, the human immune system can play an intricate role during the spreading of such contagious diseases. Some infected individuals may not have explicit symptoms, whereas others may face serious health conditions. Basically, immune response depends on how quickly human body can prepare its biological defenders for viral attack. These responses may be influenced by a bunch of factors specially the availability of vitamins C and D in our body. However, we all aware of the fact that the source of vitamin D is mainly sunlight where in presence of photons, the cholesterol underneath our skin converted into cholecalciferol or vitamin D11. Note that the average sunshine hour within any infected region can largely affect the immune response developed against infectious diseases12. In case of Covid-19, it can remain incubated inside human body up to 14 days13. During this incubation period, active immune response may suppress the replication of this virus and substantially leading to no visible symptoms and these cases are not likely to appear into the total number of cases identified14.However, since Covid-19 is a global issue and is a threat for whole human being, thus in the present research work, we attempted to unveil the relation between Covid-19 proliferation and various climatic parameters based on metrological data obtained from different zones over the globe as shown in global map in Fig.1 . For analysis, the geographically different eight locations such as Alberta (Canada), New York (USA), Rio de Janeiro (Brazil), Barcelona (Spain), Île-de-France (France), Lombardy (Italy), West Bengal (India), and Dhaka (Bangladesh) were selected based on the diversity of weather, Covid-19 cases and population. In this study, we considered first 60 days of Covid-19 proliferation since most of the local authorities paid their best efforts to sluggish/stop the proliferation within this period.