The SARS-COV-2 outbreak around the Amazon rainforest: the relevance of the airborne transmission

Background This paper presents a global analysis of the SARS-COV-2 outbreak in Brazil. Amazonian States have a much higher contamination rate than the southern and southeastern States. So far, no explanation has been provided for this striking difference that can shed light on the airborne transmission of the virus. Minimizing airborne transmission, health authorities recommend two meters as a safe distance. However, recent experiments reveal that this can be the main form of contagion. There is a lack of theoretical explanation on how airborne transmission works. Methods To investigate the spread of SARS-COV-2 in different macro environments, we analyzed the daily official data on the evolution of COVID-19 in Brazil. We compared our epidemiologic results obtained in States with very different climatic characteristics, and that had adopted, almost simultaneously, similar social isolation measures. To understand the virus spread, it was necessary to calculate theoretically the movement and behavior in the air of saliva droplets. Findings The transmission of SARS-COV-2 is much faster in the Amazon rainforest region. Our theoretical calculations explain and support the empirical results observed in recent experiments that demonstrate the relevance of aerial transmission of the coronavirus. Interpretation An onset of collective immunity may have been achieved with a contamination rate of about 15% of the Amazonian population. If confirmed, this result will have an essential impact on the management of the pandemic across the planet. The airborne transmission played a decisive role in the striking difference in the evolution of the pandemic among Brazilian regions. Air humidity is the most important climatic factor in viral spreading, while usual ambient temperatures do not have strong influence. There is no safe indoor distance for the coronavirus transmission. So, mask and eye protection are essential. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement University of Sao Paulo ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: None All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes No data