An Epidemiological Update on COVID -19

The lungs' air sacs are filled with fluid, leading to a life-threatening lung injury known as acute respiratory distress syndrome (ARDS). The tiny blood vessels of the lungs are damaged in this condition. The amount of oxygen in the bloodstream decreases, giving rise to carbon dioxide in blood circulation. This makes breathing extremely difficult, ultimately leading to organ failure. Usually, the organs damaged due to this condition are the kidneys or brain. The variations in the severity of ARDS are dependent on different signs and symptoms. Most of the time, ARDS is represented by shortness of breath, dry hacking cough, fever, headaches, and fast pulse rate. Labored and unusually rapid breathing, Low blood pressure, mental confusion, and extreme tiredness could also be other signs. ARDS can also be associated with old age, chronic lung disease, a history of alcohol misuse, or smoking

 Coronaviruses are known to infect both animals and humans. A strain of Coronaviruses known as SAR-CoV also belongs to the Coronaviruses family and is known to have caused Severe Acute Respiratory Syndromes (SARS) in 2002-03. This infection has also affected humans at a faster pace. Coronaviruses are found in various animal species like cattle and camels. Recently, Coronavirus disease, abbreviated as Covid-19, emerged as a highly transmittable and pathogenic infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is believed to have been originated in Wuhan, China, around November 2019. Currently, almost all the countries of the world have been affected by this infection, and millions of people across the globe have died with the virus so far, and the overall toll is likely to go much higher. In March 2020, this infection was labelled as a pandemic by World Health Organization. Genome analysis was conducted, which revealed similarities of Covid-19 viruses with that of SARS. This led to a hypothesis that, like SARS, Bats can also be the possible primary reservoir for Covid-19 as well. There are many theories going around regarding the origin of SARS-CoV-2; one study pointed out that Covid-19 originated from Bats while the other indicated its origin from pangolin. Both the studies failed miserably to establish the spread of Covid-19 to humans as both the animals have no frequent contact with the humans. There are a lot of pieces of evidence suggesting SARS-CoV-2 as a possible zoonotic source for COVID-19. Some theories also pointed out the laboratory origin of COVID-19, but no evidence has been provided to this claim. Contrary to this claim, its genomic sequences do not contain a mix of known elements. Studies are being conducted to know the intermediate source of origin of COVID-19 and its possible transfer to humans. A lot of vaccines have been approved against it that are supposed to prevent its spread during clinical trials conducted across the globe. These are broad-spectrum antiviral drugs that could help recover the infected patients. 

This chapter aims to assess the social, healthcare, and economic impacts of SARS-Corona Virus 2019 globally since the World Health Organization declared it a global pandemic in March 2020. The primary focus of this study is to assess the management of this disaster, our emergency response to it, and our preparedness. Currently, the pandemic has spread across the globe, leaving its impression in 196 countries, so a complete analysis of it can only be made once the pandemic ends. The epidemiological techniques and statistical modelling data of this highly infectious virus across the globe are important for conducting such studies. Currently, this data is inconsistent depending upon the climate and case-to-case scenarios. There is an urgent need for government and non-governmental organizations to work together in a coherent way to fight this disease. This deadly virus can only be neutralized by public awareness, social distancing, and vaccination.

 In December 2019, the world witnessed the spread of a new pandemic from the Wuhan city, China, which was later known as Coronavirus disease (COVID-19) caused by SARS-CoV-2. The main effects of Coronavirus disease (COVID-19) have been reported on human respiratory and cardiovascular systems, but neurological impacts have also been witnessed in most of the patients. Some common symptoms of COVID-19, such as stroke, anosmia, and dysregulation of breathing, are somehow related to the neuropathological processes. The detailed studies dealing with the neurological impacts of COVID-19 have revealed that the central nervous system is affected by SARS-CoV-2. Still, this disease also impacts the peripheral nervous system (PNS) and the muscles as well. T Guillain-Barré syndrome, Miller Fisher syndrome, polyneuritis cranialis, and viral myopathy with rhabdomyolysis are some of the diseasesthat affect muscles and the peripheral nervous system (PNS), but these diseases are usually less frequent. Usually, the symptoms of Coronavirus disease (COVID-19) impacting the neurological system are reported in cases of severe illness. Thus care must be taken during the treatment of Coronavirus (COVID-19) patients. A careful diagnosis is key before starting the treatment. This chapter aims to discuss the neuropathological impacts of the infection caused by SARS-CoV-2.

Wuhan, a Chinese city, caught the world’s attention after the outbreak of a pandemic caused by the coronavirus 2019-nCoV. Coronaviruses are a group of singlestranded positive-sense RNA that are supposed to cause various diseases in animals, including humans. The four genera of CoVs are αCoV, βCoV, ϒCoV, δCoV.CoVs. Initially, it was thought that the infection caused by these groups of viruses is only limited to their animal host. But now, they are believed to have passed from their animal host to humans and caused disease in humans. The pieces of evidence of this cross between animal-human species barrier have been supported by CoVs like the SARS CoV and MERS CoV, which has caused diseases in humans. 96% homology of the coronavirus isolated from humans matches with beta coronaviruses. The beta coronaviruses are usually found in bats in the genus Rhinolophus. Similarly, 92% homology of the SARS-CoV matches with SARS-like viruses that are found in bats. The majority of the SARS-like viruses are found in the Rhinolophus genus of the bats. This match of homology between COVID-19 virus and beta coronavirus suggests that COVID-19 virus is somehow associated with the Rhinolophus genus in Bats. Bats of this genus are widespread across Asia, the Middle East, Africa, and Europe. These links point out that there must be an intermediate host that could have probably facilitated the transfer of this virus from an animal reservoir to humans (civets were implicated as an intermediate host for SARS-CoV). Thus the similarities between SARS-CoV and the COVID-19 virus are being further investigated, and efforts are being made to identify the intermediate host.

In December 2019, a new infectious respiratory disease emerged in Wuhan, Hubei province, China. A novel coronavirus, SARS-coronavirus 2 (SARS-CoV-2), shows features that were similar to that SARS-CoV. Soon it was believed to have caused a new lung disease later on known as COVID-19. Originally, the susceptible index patient was asymptomatic and later was confirmed as COVID positive with fever, cough, and sore throat-like symptoms. Later the index patient symptoms rapidly severed along with a high respiratory rate. The severe acute respiratory syndrome coronavirus (SARS-CoV) is associated with lung injury, while acute respiratory distress syndrome may result in a pulmonary failure resulting in mortality. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) soon captured the world's attention due to its capacity to widespread fatality leading to the failure of the healthcare system across the globe. It was also revleaed by the researchers that both SARS-CoV-2 and SARS-CoV exhibited the same features while making their entry into the host cells. They made use of host angiotensin-converting enzyme II (ACE2) for their entry into the host. This enzyme is present on the host cell surface, especially in epithelial cells of respiratory organs like lungs and small intestine in humans. From the accumulated existing published data, it is obvious that the SARS-CoV-2 employs two ways for making its entry into the host cells: one path is initiated by transmembrane protease serine 2 (TMPRSS2) that lies on the surface of the cell while the other is mediated by angiotensin converting enzyme II (ACE2) endosomal pathway. On the other hand, Cholesterol and sphingolipid-rich lipid raft, and micro-domains in the plasma membrane that are used as several physiological signalling pathways, are also involved in virus entry.This chapter aims at briefly evaluating the pathogenesis of SARS-CoV and new antiviral drugs against the disease.

Research revealed that in vitro activity ofchloroquine and the derivative molecule of hydroxychloroquine is against the infection caused by the SARS-CoV and SARS-CoV-2. The US FDA approved the use of both hydroxychloroquinesulfate and chloroquine phosphate for the critical patients of COVID-19. The clinical trials supported that the hydroxychloroquine did not substantially reduce the system severity in non-hospitalized persons. Moreover, it also produces severe side effects like drowsiness, hypokalaemia, nausea, convulsions, shock, and even death.

At present, we are in a crucial situation to find out and understand the immune response for severe acute respiratory syndrome coronavirus inside of human body systems. The novel coronavirus (SARS cov-2) has to cause 35 million infections and more than 1 million deaths worldwide as on October, 2020, according to the WHO dashboard. The explosive unfolds of SARS-CoV-2 indicate that a vaccine could be required to cease this global pandemic. Progress in SARS-CoV-2 vaccine improvement thus far has been faster than for some other pathogen in history. There were 42 vaccines in clinical research, and nearly 150 vaccines are in preclinical study. The immunogenicity alone data will help to attain a goal of design and development of good and safe vaccine averse to SARS CoV-2 infections in many countries and it also helps to predict the efficacy of the COVID-19 vaccine. Still now, we do not have a particular vaccine for COVID-19 infections, only we boost up our immune system to reduce the Covid-19 infections. So, we must know about our immune systems as well as the immunogenicity of the bio-active compounds for the prediction of the valuable and most powerful vaccine. A vaccine against SARS CoV-2 must control the infection and be capable of controlling the disease or transmission. For these reasons, we can detail explaining about fundamentals and application of Immunogenicity and also discuss its application to find out the potent SARS CoV-2-vaccine in this present study. 

At the end of 2019, there was a global pandemic jeopardizing the lives of millions of people, with reports on the spread of novel coronavirus (nCoV-2019). COVID-19 or the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated from bats and was transmitted to humans through an unknown source in Wuhan city located in China and spread across the globe in early 2020. The nCoV-19 uses its spike glycoprotein receptor to bind to the host cell angiotensin-converting enzyme 2 (ACE2) sites to launch a combination of events leading to server acute respiratory syndrome. In the past 100 years, the COVID-19 pandemic is the most destructive and life-threatening disease affecting the lives of millions of people after the Spanish flu. Hence, it requires a speedy measure to curtail the spread and combat the death rates. As it is said, vaccines are found to be a commendable strategy to alleviate the viral strains. The data required for the vaccine development, including the whole genome and protein sequence of SARS-CoV-2, were made available, which enabled numerous researchers and scientists across the countries to develop multiple vaccines for prophylactic and treatment of COVID-19. All these vaccines are in various stages of clinical trials. To date, globally, only 115 vaccine candidates have been developed, out of which 78 were found to be active and 37 yet to be confirmed. Vaccine development to prevent SARS-CoV-2 has potential hurdles where regulatory and medical decisions are taken based on the ratio between benefit and risk factors. Data on the specific SARS-CoV-2 antigen(s) used in vaccine development are highly limited in public resources. The vaccine developed mainly aimed to induce neutralizing antibodies against the viral spike (S) protein, preventing uptake via the human ACE2 receptor. However, it is unclear how different forms and/or variants of the S protein used in different vaccine candidates relate to each other or the genomic epidemiology of the disease. The most advanced candidates have recently moved into clinical development, including mRNA-1273 from Moderna, Ad5-nCoV from CanSino Biologicals, and INO-4800 from Inovio. Numerous other vaccine developers have indicated plans to initiate human testing in 2020. In this review, we focus mainly on the development of the SARS-CoV-2 vaccine using recombinant technology.

Coronavirus is a vast family of RNA viruses causing diseases from fever to severe illness and even death. Initially, it was called 2019 novel coronavirus (2019- nCoV) and labelled as Severe Acute Respiratory Syndrome Coronavirus 2 (SARSCoV-2). The disease caused by coronavirus has been named coronavirus disease 2019 (COVID-19). Coronaviruses are widespread amongst birds, reptiles, cats, dogs, pigs, monkeys, rabbits, bats, and as well as in humans. SARS-CoV-2 is highly contagious and transmissible from human to human with an incubation period of up to 24 days, although the mortality rate seems to be significantly lower than SARS-CoV and MERS. Statistical data showed that on an average, an individual infected person can infect 5.7 cases.

COVID 19 is the third one among zoonotic coronavirus, first and second being SARS-CoV and MERS-CoV, respectively. WHO has declared the coronavirus disease 2019 a pandemic on March 11th, 2020. The last pandemic was reported in the year 2009, which was H1N1 flu. The early eradication of COVID 19 seems impossible as it has never been identified in humans previously. There is a need to understand the basic immunology of this disease, to develop vaccines and medicines to save the global population from this novel coronavirus. The immune system protects against pathogens by producing antibodies to kill the pathogens that enter our bodies. Lymphocytes play a major role because they recognize the virus and produce antibodies against them, but people infected with COVID 19 showed a decline in the number of lymphocytes. Lymphocytes include T-cells, B-cells, Natural killer cells. About 15% of COVID 19 patients develop pneumonia, and about 5% end up in multiple organ failure where the immune response is critically impaired. The clinical conditions associated with Covid19 include cytokine storm and acute respiratory distress syndrome (ARDS). In addition, changes in Acute Phase Reactants proteins (APR) have also been reported. This chapter aims to improve the understanding of the immune response and immunopathological changes that have been witnessed in patients suffering from this disease.