# SARS-CoV-2 Detection Using Optical Fiber Based Sensor Method
## 1 Introduction  
Since the early 2020, world has faced tremendous challenges due to SARS-CoV-2 Coronavirus disease, also known as COVID-19 * (* Official names announced for the virus responsible for COVID-19 (previously known as \"2019 novel coronavirus\"). It is a contagious disease that has caused a novel strain of flu virus. The World Health Organization (WHO) reports that the first case of COVID-19 was first witnessed in Wuhan, China in late December 2019 [1]. By early February of 2020, all parts of the world were affected, and strict restrictions were in place. WHO had declared COVID-19 as a pandemic and it has been recognized as the biggest challenge in the 21 st century [2]. The official name for the disease is coronavirus disease (COVID-19), and the virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), attacks the immune system and infects the main respiratory tract of the human body. There is evidence that COVID-19 patients suffer from one of the following symptoms: coughing, fever, loss of taste and smell, illness, fatigue, diarrhea, and flu [3]. In fact, difficulty in breathing and loss of oxygen saturation are the most significant issues that COVID-19 patients suffer from day 3 to 8. Similarly, COVID-19 patients have seen involvement of kidney and heart failures as well [4]. Millions of people have lost their lives worldwide due to the inefficient and time-consuming process of diagnostic tests. The world has entered a stage in which the realization is present in society that we have to live with this virus and the only way is to take certain precautions in order to protect yourself from these issues. In order to fight against this deadly virus, major pharmaceuticals have gained early success in development of COVID-19 vaccines and many countries have already vaccinated their citizens. It has been observed that the vaccination does not provide a foolproof defense from COVID-19 virus, however; it only makes the immune system strong enough to fight against the virus. Vaccination research is an ongoing process, and it will take some time to create a broad-spectrum vaccine that can counterfeit all the variants of COVID-19. However, the detection of infection is a high priority in the battle to conquer this pandemic. We are not only fighting against this deadly virus but also against time. The detection of COVID-19 through gene sequencing is possible using a technique called Reverse Transcription Polymerase Chain Reaction (RT-PCR) [5; 6]. This procedure takes around 8 to 12 h (at priority), which leaves the patient anxious and in ambiguity since it is not clear if the patient has been infected or not. Additionally, the detection accuracy with PCR in first 3 days of getting exposed to COVID-19 is minimal [7; 8]. The studies indicate that oropharyngeal swabs and sputum could improve the early detection of COVID-19 patients. Nevertheless, handling large amount of population, cost and equipment are the major limitations of this method. The early detection of COVID-19 will indeed improve the possibility of life expectancy of the COVID-19 patient, helping practitioners to make timely decisions and plan in a better way. Based on this, the use of optical technologies and sensors for early detection of COVID-19 has been the prime research area of investigation. Many different methodologies have been employed. The utilization of different methodologies to detect COVID-19 has become popular over the last year and a half. Examining the recent literature from Web of Science, we used the phrase \"detection\", \"diagnostic\", \"optical\", \"fiber\" and \"fibre\" as searchable items. We obtained 21,845 items, out of which only three articles discussed the utilization of fiber-optic biosensors for COVID-19 detection. These articles proposed combination of an immunoassay with the plasmons and fluorescence detection of recombinant SARS-CoV protein N. It was shown that these technologies can lead to a greater sensitivity than the conventional method.