key: cord-0724813-ajyrz0cw authors: Al-Tawfiq, Jaffar A.; Leonardi, Roberto; Fasoli, Gino; Rigamonti, Daniele title: Prevalence and fatality rates of COVID-19: What are the reasons for the wide variations worldwide? date: 2020-04-29 journal: Travel Med Infect Dis DOI: 10.1016/j.tmaid.2020.101711 sha: 9339f694f0c38cc53b989374b18ee9bbab09c493 doc_id: 724813 cord_uid: ajyrz0cw nan To the Editor, The emergence of the novel coronavirus disease-19 in December 2019 resulted in a significant number of cases as reported by the World Health Organization (WHO) and was subsequently declared by the WHO as a pandemic on Mar 11, 2020. The review of the WHO data reveals some perplexing facts. There was a genetic variation of SARS-CoV-2, the etiologic agent of COVID-19 [1] . In addition, there were three genomic variants, termed A, B, and C, based on amino acid changes. COVID-19 variant A is the ancestral type, and both A and C types are found in significant proportions in Europe and America [2] . In the absence of a documented difference in the virulence of these COVID-19 variants, it is challenging to explain the wild differences in prevalence and mortality rates in the different countries affected by COVID-19. Differences in the diagnostic efforts, or differences in the definition or reporting cannot, in our opinion, explain the wide variation of the data. Climactic conditions have been postulated as a potential explanation for heightened transmission of COVID-19 and the occurrence of community outbreaks in countries with temperature of 5-11 o C and low humidity resembles seasonal influenza [3] . However, other factors, such as greater number of commercial or tourist travel might independently influence the spread of COVID-19. Specifically, when we examined the reported data, we were struck by the great variability of the number of confirmed cases per million. According to the available data as of April 16, 2020, the When we examined the mortality rates reported by various countries, the mortality again varies greatly. Italy is reporting the highest mortality (13.1% on April 16, 2020), whereas, Iran (6.3%), China (4%), Spain (10.4%), France (11.6%) and Korea (2.1%) described lower mortality rates. At the bottom of the countries with low mortality are Bahrain and Singapore (with 0.3-0.4% mortality). Are there plausible explanations for the great variability in disease prevalence within the different countries? Social habits (greetings customs, ease to touch another person, kissing etc.) could possibly play a role, as could a greater susceptibility of the population, the presence of "super-spreaders" [4] or a delayed implementation of measures intended to stop the spread of infectious disease such as social distancing and closure of public areas. One study indicated that variation in prevalence could be due to differences in transmission and migration rates [3] . What enabled China to contain the spread of the epidemic was most certainly the coordinated effort of the central government to shut down Wuhan on January 23 rd , followed on January 24 th by the shutdown of another 15 cities: since then the number of new cases began to go down. This extremely successful endeavor is the result of draconian measures implemented with military discipline, and thus this measure maybe difficult to implement in western countries. Are there plausible explanations for the great variability in mortality rate? There was a variation in the risk of death in a study from China. -The estimates of the risk for death was 12% in the epicenter of Wuhan and 1% in other, more mildly affected areas [5] . A higher average age of the population, (particularly in Italy with a median age of (47.4 years), accompanying higher percentage of comorbidities, most likely play a significant role in death rates. In one study, older age and higher Sequential Organ Failure Assessment (SOFA) score were associated with increased mortality [6] . Sadly, in certain instances, it appears that the underlying cause of dramatically higher mortality, to this date, was a drastic decrease in availability of critical resources. This decrease in resources leads to a functional collapse of the healthcare system and an overwhelmingly and unmanageable surge of people needing assistance in the intensive care units. In the absence of a single plausible explanation for the existence of such dramatic disparities, we feel that home quarantine and isolation of the vulnerable populations (such as the elderly and the frail) along with the draconian measures being implemented in many countries are justified in order to successfully contain and eventually overcome the current pandemic due to COVID-19. A conflicting interest exists when professional judgement concerning a primary interest (such as patient's welfare or the validity of research) may be influenced by a secondary interest (such as financial gain or personal rivalry). It may arise for the authors when they have financial interest that may influence their interpretation of their results or those of others. Examples of potential conflicts of interest include employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding. All sources of funding should also be acknowledged and you should declare any involvement of study sponsors in the study design; collection, analysis and interpretation of data; the writing of the manuscript; the decision to submit the manuscript for publication. If the study sponsors had no such involvement, this should be stated. Signature (a scanned signature is acceptable, Print name but each author must sign) ____________died on March 13, 2020__ ____________ Gino Fasoli __ Manuscript number (if applicable): How could we explain the wide variation of the data of COVID-19 prevalence and fatality rates? Author name: Gino Fasoli Travel Medicine and Infectious Disease requires that all authors sign a declaration of conflicting interests. If you have nothing to declare in any of these categories then this should be stated. A conflicting interest exists when professional judgement concerning a primary interest (such as patient's welfare or the validity of research) may be influenced by a secondary interest (such as financial gain or personal rivalry). It may arise for the authors when they have financial interest that may influence their interpretation of their results or those of others. Examples of potential conflicts of interest include employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding. All sources of funding should also be acknowledged and you should declare any involvement of study sponsors in the study design; collection, analysis and interpretation of data; the writing of the manuscript; the decision to submit the manuscript for publication. If the study sponsors had no such involvement, this should be stated. Signature (a scanned signature is acceptable, Print name but each author must sign) ______ ________ ____________Jaffar A. Al-Tawfiq__ Manuscript number (if applicable): How could we explain the wide variation of the data of COVID-19 prevalence and fatality rates? Author name: Jaffar Al-Tawfiq Genomic diversity of SARS-CoV-2 in Coronavirus Disease 2019 patients Phylogenetic network analysis of SARS-CoV-2 genomes Potential impact of seasonal forcing on a SARS-CoV-2 pandemic Super-spreading events and contribution to transmission of MERS, SARS, and COVID-19 Estimating Risk for Death from 2019 Novel Coronavirus Disease, China Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study