Abstract
During December 2019, a rapid increase in the number of SARS-CoV-2 (COVID-19) cases was reported worldwide. We investigated several factors for rapid increase in SARS-COV-2. Genomic sequence reveals that domestic and wild animals were likely ancestors and zoonotic source for SARS-CoVs, MERS-CoVs, and SARS-CoV-2; these viruses replicated in animals and humans during past several decades, exhibiting diverse mutations and self-limiting diseases except during outbreaks. SARS-CoV-2 has been retrospectively isolated in different studies in August 2019, several months before Wuhan reported. Hence, there is a possibility that viruses went undetected and infecting sub-clinically, in past several years, and SARS-CoV-2 antigens and neutralizing antibodies may have been present in humans since years. All SARS-CoVs are basically respiratory viruses, spread by droplets, hence droplet precautions are essential. Furthermore, silent phase of transmission (asymptomatic/subclinical) can be beneficial for humans. Lack of symptoms eventually lessen virus transmission and reduce the pathogen's long-term survival and provide strong humoral herd immunity (with sropositivity and diverse antibodies) up to several years and during epidemics. RT-PCR has low sensitivity and specificity, carries a high risk of handling live virus antigens, and requires difficult protocols. As viral load also sharply declines after few days of onset of infection, this technique might overlook infection. Furthermore, SARS-CoV-2 infection may be present in blood when oropharyngeal swabs are negative by RT-PCR. Conversely, antibodies against SARS-CoVs develop robustly in by reduced amount of antigens and ELISA for diagnosing antibodies demonstrates 100% specificity and 100% sensitivity, even in clinically asymptomatic individuals. These antibodies can be used for serologic surveys, monitoring and screening. Furthermore, screening tests for SARS-COV-2 should be avoided in unhygienic public places by nasopharyngeal swabs, which carry a high risk of further transmission, co-infection or super-infection. If above mentioned factors and Infection control policy is followed, SARS-CoV-2 pandemic can be controlled effectively.
Highlights
During December 2019, one of the novel coronavirus infections SARS-CoV-2 (COVID-19) outbreak occurred in Wuhan, China
Coronaviridae Study Group of the International Committee on Taxonomy of Viruses has clearly stated that "The Study Groups quantify and partition the variation in the most conserved replicative proteins encoded in open reading frames 1a and 1b (ORF1a/1b) of the coronavirus genome" and that " these viruses were isolated at different times and locations from different human and animal hosts, they all belong to the species Severe acute respiratory syndromerelated coronavirus, and their relationship parallels that between human individuals and the species Homo sapiens"
Study done by Leung et al have done serologic survey for immunoglobulin IgG against SARS-CoV in a representative sample of close contacts of all SARS patients by viral lysate enzyme linked immunosorbent assay (ELISA) and Positive results were confirmed with immunofluorescence assay (IFA) and neutralization tests
Summary
During December 2019, one of the novel coronavirus infections SARS-CoV-2 (COVID-19) outbreak occurred in Wuhan, China. Several research papers were published, identifying the characteristics of this virus with nearly one thousand publications worldwide. Most of these publications are based on the information from one aspect, not encompassing all the causative factors which are leading to the increasing frequency of the current pandemic. Previous publications have not collected all reports with systemic review; and several biological transmission facts were missed. To limit SARS-CoV-2 (COVID-19) infections and pandemic emergencies, and to understand all scientific facts, here we have summarized different aspects of this disease with systemic review
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