1  INTRODUCTION
CoVs were recognized as “novel respiratory tract viruses” over half a century ago. The title was conferred in 1962, following the examination of samples collected from individuals who had manifested symptoms of respiratory tract infection (Hamre & Procknow, 1966). Initially, CoVs were not considered as highly pathogenic for humans. That was until 2002, however, that CoVs emerged in the form of Severe Acute Respiratory Syndrome (SARS) in the Guangdong state of China (Sahin et al., 2020). Almost a decade later, another highly pathogenic CoV appeared in the Middle East countries, which similarly led to severe respiratory symptoms of acute onset. The then‐novel species was named Middle East Respiratory Syndrome Coronavirus (MERS‐CoV; Zaki, Van Boheemen, Bestebroer, Osterhaus, & Fouchier, 2012).
In December 2019, a cluster of insidious Coronavirus infections was reported in the Huanan Seafood Market, located in Wuhan State of Hubei Province in China. Unlike the name, livestock animals were also traded in the market alongside their marine relatives. Days later, the cluster turned into a local network and set off the alarm for the Chinese government. It was then that a pneumonia epidemic of unknown cause became the focus of global attention (Sahin et al., 2020). Chinese authorities announced on January 7, 2020 that a new type of CoV (novel CoV, nCoV) was isolated (Imperial College London, 2020; World Health Organization, 2020). On December 12, 2019, a pneumonia case of unknown origin was reported in Wuhan, China. Initial laboratory tests ruled out Influenza and infection with recognized CoVs. Following the incident, 27 new cases of pneumonia of viral origin were officially reported on December 31, 2019. A week later on January 7, 2020, the Chinese authorities announced that a new species of CoV was isolated in the country (Zumla, Hui, Azhar, Memish, & Maeurer, 2020).
Given the whereabouts of the first case ever reported, the infection was speculated to have been contracted from a zoonotic agent. Etiologic investigations on patients who had been hospitalized with a similar medical history supported the likelihood of a viral infection transmitted from animals to humans (Sahin et al., 2020; World Health Organization, 2020; Yin & Wunderink, 2018). nCoV was duly reported to have been originated from wild bats. Falling in the category of group 2 β‐CoVs, the novel Coronavirus only shares a 70% similarity in genetic sequence with its predecessor, SARS‐CoV, which also belongs to the exact same family (Gralinski & Menachery, 2020).
The tantalizing surge in the number of cases infected with SARS‐CoV‐2 in China, despite the closure of markets and evacuation of the vicinity, fulfilled the burden of proof that the virus can also be transmitted from human to human. Soon thereafter, peculiar cases of acute respiratory syndrome started appearing in other Asian countries, ultimately spreading to North America and Europe. (Sahin et al., 2020; World Health Organization, 2020; Yin & Wunderink, 2018). Following an emergent briefing on January 30, 2020, The World Health Organization (WHO) declared the outbreak of COVID‐19 as a Public Health Emergency of International Concern (Organization, 2020).
The epidemic began to emerge with the advent of the Chinese New Year, a traditionally important festival that is heavily celebrated across the country. The coincidence paved the way for SARS‐CoV‐2 to turn into an unprecedented massive Coronavirus outbreak, which required extensive measurements to be contained. With a population of 10 million, Wuhan City also served as an important pathway for millions of people traveling in celebration of the Spring Festival. Accordingly, the number of cases to be diagnosed with COVID‐19 showed an overwhelming increase between January 10–22, 2020 (Chen, Zhang et al., 2020).
Despite the arbitrary speculations, not only did the recent outbreak of COVID‐19 egress the country of origin, it also proceeded to become a global concern in the form of a pandemic (Yang et al., 2020). COVID‐19 is an acute self‐resolving respiratory disease in most of the cases, however, it can also be fatal in some cases. The disease was initially reported to have a mortality rate of 2%. If severe, COVID‐19 might result in death as a result of the preceding extensive alveolar damage, and failure of the lungs (Xu et al., 2020). As of February 15, 2020, a total of 66,580 cases had been confirmed, with over 1,524 deaths. However, there have no specific reports on pathology, as performing an autopsy or biopsy was not possible in most of the cases (Chan et al., 2020; Huang et al., 2020). Table 1. Represents the WHO situation reports on March 24, 2020 (www.WHO.int).
Table 1  The number of cases and death of Covid‐19 outbreak according to World Health Organization statistics (April 13, 2020)
Region  Total (new) cases in last 24 hr  Total (new) death in last 24 hr
Globally  1,773,084 confirmed (76,498)  111,652 deaths (5,702)
Western Pacific Region  121,426 confirmed (1,310)  4,125 deaths (67)
European Region  913,349 confirmed (33,243)  77,419 deaths (3,183)
South‐East Asia Region  16,883 confirmed (842)  766 deaths (38)
Eastern Mediterranean Region  99,713 confirmed (3,768)  5,107 deaths (164)
American Region  610,742 confirmed (36,804)  23,759 deaths (2,228)
African Region  10,259 confirmed (531)  464 deaths (21)
John Wiley & Sons, Ltd. This article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original source, for the duration of the public health emergency. A total of 8,096 SARS cases and 774 deaths across 29 countries were reported for an overall case‐fatality rate (CFR) of 9.6%. MERS is still not contained and is thus far responsible for 2,494 confirmed cases and 858 deaths across 27 countries for a CFR of 34.4%. Despite the much higher CFR of 9.6% and 34.4% for SARS and MERS, the novel Coronavirus epidemic has led to a larger death toll. The Chinese government had reported 72,528 confirmed cases, with 1,870 deaths, as of February 18, 2020. These statistics yield a crude CFR of 2.6%. However, one should not haste to generalize this number, as most possibly the total number of patients with COVID‐19 is much higher. That is, because the cases are not readily identifiable, as many asymptomatic patients are missed during the process (Wu et al., 2020; Yan et al., 2020). Despite the higher transmissibility than SARS and MERS, COVID‐19 is still a relatively unknown disease and requires further investigations to be fully understood (Yan et al., 2020).