key: cord-325377-g68onkjt
authors: Dey, Anusree; Das, Rituparna; Misra, Hari Sharan; Uppal, Sheetal
title: COVID-19: Scientific Overview of the global Pandemic
date: 2020-10-28
journal: New Microbes New Infect
DOI: 10.1016/j.nmni.2020.100800
sha: 
doc_id: 325377
cord_uid: g68onkjt

COVID-19 (Coronavirus Disease 2019) is the disease caused by the novel Coronavirus, SARS-CoV-2. Genome sequence of the virus revealed that it’s a new zoonotic virus which might have evolved by jumping from bats to humans with one or more intermediate hosts. The immediate availability of the sequence information in public domain has accelerated development of quantitative-reverse-transcription PCR based diagnostics. Besides, numbers of clinical trials have been prioritized globally for testing new vaccines and treatments against this disease. This review gives a broad insight into different aspects of the COVID-19 disease, introduction to SARS-CoV-2, mitigation strategies, present status of diagnostics and therapeutics.

In December, 2019, a cluster of patients, linked to a local sea food market in Wuhan city of 12

Hubei Province, China, were diagnosed with a viral pneumonia having SARS (Severe Acute 13

Respiratory Syndrome) like symptoms of unknown etiology [1] . Initial denials of human-to-14 human transmission of the virus, which were later refuted in January 2020, led to a rapid 15 spread of the disease throughout China within a short span of time. Following this, the virus 16 spread like wildfire both within China and across the globe with more than 210 countries 17 affected. 18

In January 2020, the first genome sequence of the virus was released by Prof. Yong-Zhen 19

Zhang [Genbank accession: MN908947]. Based on its genome sequence similarity to SARS 20

Coronaviruses, it was identified as a novel Coronavirus and was named SARS-CoV-2. 21

Coronaviruses (CoVs) refer to the largest group of viruses characterized by a spherical 22 morphology with a single-stranded RNA surrounded by an outer envelope (Fig. 1) . J o u r n a l P r e -p r o o f CoV-2 belongs to the genus Betacoronaviruses, one of four genera of coronaviruses, which 24 also include SARS-CoV-1 and MERS (Middle East respiratory syndrome)-CoV etc. (Fig. 2 ) 25 [1, 2] . The genome sequence of the novel coronavirus revealed that, similar to other 26

Coronaviruses, SARS-CoV-2 has a zoonotic origin and mainly thought to have jumped from 27 bats to humans with one or more intermediate hosts ( The disease caused by the novel coronavirus, SARS-CoV-2, was referred to as Coronavirus 38

Disease 2019 of COVID-19 associated coagulopathy has also gained significant prominence, following 65 exhibition of multifarious neurological manifestations by a significant proportion of the 66 patients. Ischemic stroke, cerebral hemorrhage and thrombosis are some of the more common 67 symptoms [9]. However, mortality to a larger extent is also determined by access to quality 68 healthcare. According to the global data as well as the early estimates from China, both old 69 J o u r n a l P r e -p r o o f age and comorbidities may render the patients at higher risk of developing severe disease or 70 death due to COVID-19 infection, perhaps due to a weaker immune functioning [8, 10] . 71

The duration between the onset of infection and appearance of the first symptom of the 72 disease in an individual is defined as incubation period. SARS-CoV-2 incubation period is 73 typically around 5-6 days (ranging from 0-14 days) [5, 11] , which is similar to its distant 74 cousin, SARS-CoV-1 (4-6 days and upto 10 days in some cases) found to have more severe symptoms [16] . 112

A virus genome may accumulate mutations while it replicates inside the host cell thereby 114 generating genomic variants across the globe. SARS-CoV-2 mutates, albeit at a slow rate 115 J o u r n a l P r e -p r o o f [17] . Characterization of these variants may be helpful in understanding the disease 116 mechanism, how the virus evades the immune system or develops resistance to drugs. Having 117 stated that, it will be premature to infer from the currently available data that a particular 118 mutation makes the virus more virulent than others. A recent study found two major versions 119 of the SARS-CoV-2 coronavirus, called clade I and clade II, based on the genome sequence 120 analysis of more than 100 sequences [16] . The two clades were not found to be any different 121 in terms of contagiousness or disease severity. The disease severity largely depended on host 122 factors such as age, lymphocytopenia, and its associated cytokine storm, not so much on the 123 viral genetic variation [16] . Interestingly, in an independent study, researchers have found 124 three blood based biomarkers which can predict disease severity at least ten days in advance 125 with more than 90% accuracy, based on a database of 485 infected patients from Wuhan, 126

China. Based on these results, the disease severity was found to be associated with high level week for IgM and 2-3 weeks for IgG). Therefore, it can be used for initial screening of the 167 population followed by a more confirmatory test like qRT-PCR. Apart from its use for rapid 168 detection of infection during symptomatic period, the serological test could be used even after 169 the infection has receded, as the antibodies may remain in blood for longer period. This will 170 make it a perfect tool for population studies to get more accurate transmission data world- Remdesivir has shown positive outcome, a modestly speed recovery of the treated patients, in 198 the NIH funded randomized placebo control clinical trials [25 ] . Remdesivir will also be tested Although lesser in number, there have been instances of serious illness and even deaths in young and healthy individuals.

Fever in 88% of infected cases, often accompanied by fatigue, nausea or diarrhea.

Fever with dry cough and muscle pain.

Day 5-6 + Breathing difficulties

Recovery for some patients, however, hospitalization may be needed for patients with severe conditions (~15 %), may develop Acute Respiratory Distress Syndrome (ARDS) due to fluid accumulation in the lungs.

Some cases may worsen needing admission to the Intensive Care Unit (ICU).

For most of the people fever ends while coughing may still persist Day 13-14 For patients headed towards recovery, breathing problems may end at this stage. Day 17-18 Full recovery, however, in some cases (5%), it may lead to death.

J o u r n a l P r e -p r o o f strict precautionary measures Therefore, it is essential for every individual to take precaution irrespective of their age and health COVID-19 can be detected by Thermal scanners Thermal scanners CANNOT detect COVID-19

The prolonged use of medical masks may cause CO2 intoxication or oxygen deficiency

The prolonged use of medical masks when properly worn, DOES NOT cause CO2 intoxication nor oxygen deficiency Exposure of self to UV light may kill the virus UV radiation is extremely harmful for eyes and skin, should not be used to should NOT be used to disinfect hands or other areas of your skin. Consumption or injection of disinfectants will kill the virus in the body Disinfectants are effective in killing the virus on inanimate surfaces. However, they are extremely toxic for ingestion.

A novel coronavirus from 290 patients with pneumonia in China

Evolutionary Trajectory for the Emergence of 292

Novel Coronavirus SARS-CoV-2

A pneumonia outbreak 294 associated with a new coronavirus of probable bat origin

COVID-19 Disease due to 296

SARS-CoV-2 (Novel Coronavirus)

Clinical Characteristics 302 and Differential Clinical Diagnosis of Novel Coronavirus Disease

Coronavirus Disease 2019 (COVID-19)

Coronavirus Disease 2019 and Stroke: Clinical Manifestations and Pathophysiological

Comorbidity and its 309 impact on 1590 patients with COVID-19 in China: a nationwide analysis

COVID-19) From Publicly Reported Confirmed 313 Cases: Estimation and Application

Evidence Supporting Transmission of Severe 315

Acute Respiratory Syndrome Coronavirus 2 While Presymptomatic or Asymptomatic

Receptor Recognition by the Novel 318

Coronavirus from Wuhan: an Analysis Based on Decade-Long Structural Studies of 319 SARS Coronavirus

COVID-19 infection: Origin

The trinity of COVID-19: 323 immunity, inflammation and intervention

Viral and host factors related to the 325 clinical outcome of COVID-19

Geographic and Genomic Distribution of SARS-CoV-2

An interpretable 329 mortality prediction model for COVID-19 patients

Large 331 scale genomic analysis of 3067 SARS-CoV-2 genomes reveals a clonal geo-332 distribution and a rich genetic variations of hotspots mutations

Cas12-based detection of SARS-CoV-2

Laboratory diagnosis of COVID-336 19: current issues and challenges

Development and clinical application 338 of a rapid IgM IgG combined antibody test for SARS CoV 2 infection diagnosis

Drug targets for 341 corona virus: A systematic review

Remdesivir for the Treatment of Covid-19 -Preliminary Report

Tocilizumab among patients 347 with COVID-19 in the intensive care unit: a multicentre observational study

Adults Hospitalized with Severe Covid-19

An Updated Systematic Review of the 353

Therapeutic Role of Hydroxychloroquine in Coronavirus Disease-19 (COVID-19)

Regalado EP. Vaccines for SARS-CoV-2: Lessons from Other Coronavirus Strains

Herd Immunity: Understanding COVID-19

The authors declare that they have no competing interest. 288

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