**Abstract**

In December 2019, an unexpected outbreak was caused by novel corona virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The lung disease caused by SARS-CoV-2 was given the name of the novel coronavirus disease 2019 (COVID-19) by the World Health Organization (WHO) on February 11, 2020. Since its origin in the Hubei province of Wuhan city in China, now it has spread to 218 countries worldwide. Panic situation created by COVID-19 has compelled researchers and doctors to work collaboratively. To combat with the disease, every control measures are under consideration from drug discovery to vaccine development. In the management of disease, rapid diagnosis is equally important as development of vaccine and drug. At present, various diagnostic kits are available for COVID-19. With the disease progression, global demand for diagnostics is raising. So, this chapter will include the updates on efficient diagnostic assays and future of diagnostic.

**Keywords:** novel corona virus, COVID-19, SARS-CoV-2, diagnosis, COVID-19 management

#### **1. Introduction**

COVID-19 is now a global health emergency as the number of confirmed COVID-19 cases worldwide exceeds 75 million, while the number of global deaths exceeds 1 million. WHO has already declared COVID-19 as a public health emergency of international concern (PHEIC) on January 30, 2020 and a pandemic on March 11, 2020. New COVID-19 cases and deaths are continuously rising. Globally, there have been 106,797,721 confirmed cases and 2,341,145 deaths as per a WHO report on February 11, 2021, since the pandemic started [1, 2]. At the start of pandemic, the regions of the America and Europe were affected badly, contributed 85% of new cases and 86% of new deaths globally. The USA and India are top two countries with more than 10 million confirmed cases and 313,748 and 145,810 deaths, respectively [3]. The infection starts to spread from the seafood wholesale market in Wuhan, China, while the exact origin of the first case remains unclear. Initially, COVID-19 spread, from china to other countries, was due to travelers who got infected in China and then moved outside of the China [4]. Countries who have reported travel-associated spread were Singapore, Japan, Republic of Korea, Malaysia, Vietnam, Australia, the United States of America, Germany, etc. [4, 5]. Current, corona virus outbreak is third after the SARS and MERS corona virus outbreaks. SARS-CoV-2 virus evolved in such a manner that the spread of COVID-19 is more severe than that of the previous severe acute respiratory syndrome (SARS)

and the middle east respiratory syndrome (MERS) [6]. Currently, the COVID-19 pandemic has reached to a threatening new phase. New strains from UK with more infectivity are being reported. SARS-CoV-2 belongs to family *Coronaviridae* and order *Nidovirales*. SARS-CoV-2 stands together with two highly pathogenic viruses, SARS-CoV and MERS-CoV as belongs to Betacoronavirus genera [7]. Corona viruses are enveloped, positive-sense, single-stranded RNA viruses. Transmission of SARS-CoV-2 was initiated first from infected animals to humans and then spread rapidly throughout the world via human to human. It spreads via contact to respiratory droplets or aerosols through nosocomial transmission from an infected to uninfected [8]. As COVID-19 causes enormous human casualties and serious economic loss, we are in the urgent need of efficient vaccine and drug development against this dreadful virus. Globally, various serious efforts are being made in this direction. Governments of many countries have taken immediate action and precautionary measures against the virus. Countrywide lockdown were imposed to minimize human contact at public places. Social distancing, hygiene, and self-quarantine limit social interactions and spread of the disease. To control and manage the present pandemic situation the entire world is working and taking necessary steps. To propagate research in this field, governments are providing enough funds for scientists and institutions. To combat with the disease, both preventive and curative approach is considered. We have many potential vaccine candidates that are yet to be approved. Recently in mid November, four groups have reported about the efficacy of their vaccines. Vaccination has been started in many countries like USA, India. Pfizer-BioNTech COVID-19 vaccine and Moderna's COVID-19 vaccine have been approved by FDA recently [9].

To cure the infected patient, several drugs are being tested and used. Drugs that are currently in clinical trials are repurposed drugs, which were designed for other disease including antiviral and antimalarials [10–13]. Other natural product-based formulations are also tested in the management of the disease, for example, Indian giloy (*Tinospora cordifolia*) and ashwagandha [14, 15]. Because of continued spread of COVID-19, accurate diagnosis of people becomes necessary. Rapid screening of an infected person before transmission onto others is essential to curb the disease. Delay and inaccurate diagnosis will give patient a chance to spread the virus. Present pandemic has enforced researchers to work at breakneck speed. As a major contribution toward diagnostic of COVID-19, various detection methods have been developed. Primarily we have molecular-based approaches to confirm suspected cases. Realtime reverse transcription-polymerase chain reaction (RT-PCR)-based testing is the main technique for laboratory diagnosis. Virus antigen- or serological antibodybased assays are also available with the advantage of a short turnaround time for the detection of novel corona virus infection. In this chapter, we will discuss and review the available COVID-19 detection methods and future prospectus of the same.
