Special Issue “SARS-CoV-2: Epidemiology and Pathogenesis”: Editorial

Since its emergence in 2019 in Wuhan City, Hubei Province, China, SARS-CoV-2 has spread across hundreds of countries and all continents [...].

Since its emergence in 2019 in Wuhan City, Hubei Province, China, SARS-CoV-2 has spread across hundreds of countries and all continents. As the virus is easily transmitted from person to person, it has caused the most serious public health emergency that the world has faced since the Spanish flu.
Over the past three years of the COVID-19 pandemic, a large number of scientific papers have been published in various journals in an effort to quickly fill the fundamental knowledge gap on this new virus. This Special Issue was a small attempt to provide a contribution to the scientific debate on SARS-CoV-2 virus infection and allow scientists and professionals actively working on the surveillance, prevention, or control of the COVID-19 disease to share their experiences and findings with the rest of the scientific community.
This Special Issue, comprising 22 articles, aimed to highlight the most recent outcomes of scientific research on the pathogenesis, epidemiology, and diagnosis of SARS-CoV-2 infection, including aspects related to animal reservoirs, virulence factors, viral evolution, control measures applicable at local and international levels, and the impact on global and local economies.
The contributions came from all continents (15 from Europe, 3 from America, 2 from Asia, 1 from Africa, and 1 from Australia), with authors from 14 different countries; thus, these articles represent a great variety of situations and experiences. Concerning the topics, the majority of the papers (n = 11) dealt with the epidemiology of SARS-CoV-2 infection in various contexts, while 10 articles focused on specific aspects characterizing the pathogenesis of the disease. One paper provided interesting insights into vaccines.
Looking at the affiliations of the authors, a wide spectrum of disciplines and institutions are represented, including medical institutes, universities, hospitals, genetic and research centers, public health organizations, and veterinary institutions. This multidisciplinary composition of the contributors to this Special Issue provides the readers with multiple and original views and approaches, enriching the scientific debate on SARS-CoV-2 epidemiology and pathogenesis.
It is noteworthy that most papers in this Special Issue, regardless if the topics address epidemiology or pathogenesis, are aimed at inferring useful information for improving the surveillance, diagnosis, prevention, and control of COVID-19, and help to elucidate the main transmission routes and pathogenetic mechanisms.
Concerning papers dealing with pathogenetic mechanisms, Kalkeri et al. [1] developed a BSL-2 pseudovirus-based neutralization assay (PBNA) useful for measuring the neutralization ability of candidate vaccines in both preclinical models and clinical trials. Another paper attempted to elucidate the structural, surface, and functional properties of viral proteins [2]. Other articles investigated the persistence of SARS-CoV-2 viral RNA in dead patients [3]; the efficacy of antiviral agents against SARS-CoV-2 [4]; the prognostic value of eosinopenia [5]; the interactions between human and viral proteins [6]; the cross-reaction of SARS-CoV-2 with antibodies against other human coronaviruses and its significance for the establishment of the immunity [7]; the whole genome intra-host variability of SARS-CoV-2 in the upper and lower respiratory tract in patients [8]; the immune response, inflammatory reactions, and viral replication in COVID-19 disease [9]; and the pathogenicity and transmissibility of the Delta and Lambda variants [10].
Some papers dealing with epidemiological features focused on the temporal and/or geographic distribution of SARS-CoV-2 lineages [11][12][13][14], whereas others explored the epidemiological significance of diagnostic findings [15][16][17][18]. Two papers presented different approaches for predicting the occurrence of infection [19,20], whereas one article discussed the main biological, ecological, and economic drivers facilitating the emergence of SARS-CoV-2 and its spread worldwide [21]. Finally, one paper explored the various possible candidate vaccines and their possible use on a large scale [22].
It is to be noted that the concerted research efforts by the scientific community globally, supported by substantial investments by governments and other organizations across the globe, have been responsible for a broad range of innovations related to virus characterization, testing, and sequencing, as well as disease pathogenesis and the development of effective vaccines and a few drugs in a record time. Lessons learned from this pandemic puts us in good stead to respond rapidly and effectively to new viruses and/or pandemics in the future.
Author Contributions: Conceptualization, P.C.; writing-original draft preparation, P.C.; writingreview and editing, H.G. and A.L. All authors have read and agreed to the published version of the manuscript.

Conflicts of Interest:
The authors declare no conflict of interest.