COVID-19 IS NEW,CORONAVIRUS ISN'T

The entire world has come to a standstill due to the unprecedented impact of the COVID-19 pandemic. Let us look at how various outbreaks of corona viruses have affected us throughout history.

M Sai Madhur

To say that 2020 has been an eventful year so far would also be a massive understatement. A lot of us were initially shocked at the prospects of a disease that can cause respiratory-tract-infections and be responsible for thousands of deaths worldwide, with mere human-contact to exist in the world. It was baffling that a microorganism would confine all of us in our homes, and halt the world. As we are adjusting to this new routine, we are also consuming a plethora of information and misinformation about this pandemic that is going around online. A video of a 2018 South Korean Drama My Secret Terrius, where a character talks about how a mutant coronavirus would be lethal enough to destroy the world, has become viral, leaving the viewers perplexed about how a K-Drama would predict something as heinous as this, two years ago. The point that should not to be missed is that while COVID-19 is new, coronavirus isn't.

The origins of the discovery of coronavirus can be traced back to 1930s when domesticated chickens were infected by an acute respiratory infection caused by Infectious Bronchitis Virus (IBV). Mobile Hepatitis Virus (MHV) and Transmissible Gastroenteritis Virus (TGEV) were discovered in the 1940s, which also affected animals. The foremost cases of coronaviruses affecting humans were discovered in the 1960s when patients of common cold were tested. HCoV-OC43 and HCoV-229E are the viruses responsible for the common cold, with the former infecting cattle and the latter infecting bats along with humans. These were the only two human-coronaviruses known until the outbreak of Severe Acute Respiratory Syndrome (SARS), that was first detected in China, in 2002.

SARS, an enveloped, positive-sense, single-stranded RNA virus which infects the epithelial cells within the lungs, was first identified when a farmer was believed to be an intermediary of civets to cave-dwelling horseshoe bats in the Shunde district of Foshan County, in Guangdong in the Yunnan Province of China in November 2002. Initially deemed to be cases of atypical pneumonia, it spread throughout China with the turn of the year. The Republic of China was criticized for notifying WHO, after three months of the outbreak and also notoriously downplaying the number of victims that the illness had claimed. The outbreak of SARS

COV-1 peaked in mid-February and over the next few months, it had spread across 29 countries with 8437 people contracting it, while 813 had succumbed to the epidemic, according to a report by WHO. One of the reports by WHO also suggests that China and Hong Kong were the most affected with 5,327 cases and 349 deaths in the former; and 1,755 cases and 299 deaths in the latter. The symptoms that the patients experienced were headaches, fever, and a type of pneumonia that could cause respiratory failure, the likes of which were ambiguous to the medical fraternity by then, subsequently creating a tremendous amount of disarray and panic. However, with effective measures taken by countries collectively to quarantine and isolate people with the illness, the person-to-person transmission of SARS was declared to be contained by WHO; on July 5, 2003.

A year after the declaration by WHO that SARS had ceased to exist, a new species of Coronavirus was identified in the winter of 2004 in the Netherlands, when a sevenmonth-old child showed symptoms suggesting respiratory tract infection (coryza, conjunctivitis, and fever), while his chest X-ray showed typical features of bronchiolitis. The virus was identified as a member of the Coronaviridae family by a group of Dutch scientists and was subsequently named as HCoV-NL63. The virus, found primarily in young children, and immunocompromised

patients also had a seasonal association in temperate climates. A study performed in Amsterdam estimated its existence in approximately 4.7 per cent of common respiratory illnesses. In January 2005, a 71-yearold in Hong Kong was hospitalised with acute respiratory distress and radiographically confirmed bilateral pneumonia, and was later identified to have been infected by Human Coronavirus-HKU1 (HCoV-HKU1). Phylogenetic analysis of the genomic sequence of the virus was similar to MHV and unique from the other coronaviruses that affected humans. The symptoms included community-acquired pneumonia, common cold, and bronchiolitis. While SARS, HCoVNL63 use ACE2 receptor to enter its host cell, it was detected that HCoV-HKU1; also an enveloped, positive-sense, single-stranded RNA virus was found to enter its host cell by binding to the N-acetyl-9-O-acetylneuraminic acid receptor. The severity and escalation of the infection of both HCoV-NL63 and HCoV-HKU1 varied from SARS, and were less harmful than the 2002-03 epidemics.

Seven years later, a viral respiratory disease caused by a novel coronavirus - MERSCoV was first detected in Saudi Arabia in 2012. The symptoms included fever, cough and shortness of breath with some patients also indicating gastrointestinal symptoms. Some reported cases of MERS-CoV were also reported to be asymptomatic (no signs or clinical symptoms but test positive for the infection). "Although most human cases of MERS-CoV infections have been attributed to human-to-human infections in health care settings, current scientific evidence suggests that dromedary camels are a major reservoir host for MERS-CoV and an animal source of MERS infection in humans. However, the exact role of dromedaries in the transmission of the virus and the exact route(s) of transmission is unknown", stated a report by WHO on the Middle East Respiratory Syndrome. Since 2012, the MERS-CoV has spread across 27 countries, infecting 2,494 people, claiming 854 lives, with approximately 80% of the cases being reported in Saudi Arabia. The mortality rate of MERSCoV has been the highest when compared to all other coronaviruses, killing 35 per cent of the total number of people infected.

Towards the end of 2019, the health-care

authorities of Wuhan, the capital of Hubei Province in China reported a cluster of pneumonia cases of an unknown cause on December 31, 2019. The cases were connected to the Huanan Seafood Wholesale Market, so the virus was thought to have had a zoonotic genesis. "The virus (termed SARS-CoV-2) shares 88% sequence identity to two coronaviruses found in bats, batSLCoVZC45 and bat-SL-CoVZXC21, 79% identity with the Severe Acute Respiratory Syndrome (SARS) coronavirus and 50% identity with Middle Eastern Respiratory Syndrome (MERS) coronavirus", reported an article in the European Journal of Immunology. The symptoms exhibited by the infected patients included fever, dry cough, fatigue and shortness of breath with some patients showing signs of gastrointestinal problems. The virus was found to be extremely contagious and spread among humans via small droplets produced through coughs, sneezes, and touches. The World Health Organization (WHO) declared the outbreak to be a Public Health Emergency of International Concern on January 30, 2020. It was renamed as SARS CoV-2 by the International Committee on Taxonomy of Viruses on February 11, 2020; since viruses are named based on their genetic structure to facilitate the development of diagnostic tests, vaccines and medicines, according to ICTV. The World Health Organisation had a different opinion on naming the virus to be SARS CoV-2 and decided to use the name COVID19 to communicate with the public. "From a risk communications perspective, using the name SARS can have unintended consequences in terms of creating unnecessary fear for some populations, especially in Asia which was worst affected by the SARS outbreak in 2003. For that and also other reasons, WHO has begun referring to the virus as "the virus responsible for COVID-19" or "the COVID-19 virus" when communicating with the public. Neither of these designations is intended as replacements for the official name of the virus as agreed by the ICTV", stated WHO on its announcement on 11th February 2020. WHO recognised COVID-19 to be a pandemic on March 11, 2020.

Although all the aforementioned viruses are part of the same family, they vary in severity and fatality. COVID-19 has had the largest reach both in terms of the number of cases reported and the countries that it has affected. Fortunately, the mortality rate of COVID-19 has been estimated to be around 2-3 percent, which is the lowest as compared to 10 per cent in SARS, and 35 percent in MERS. Nonetheless, with the gargantuan number of victims because of COVID-19, the deaths alone have mounted to 4x the number of cases reported due to SARS and MERS collectively, as on April 1, 2020. While China was the epicentre of COVID-19 till the end of February, the momentum had shifted to Europe with Italy being the worsthit in the first 2 weeks of March, the epicentre has now moved further west, with the USA reporting more than 2,00,000 positive cases.

The lessons from the fight against SARS and MERS are quite evident. Without the availability of the vaccine, the only way to stop the spread is to quarantine the affected patients. Millions of healthcare professionals from around the world have been at the forefront of the fight against COVID-19. The severity of the pandemic has forced several countries including India with a population of 1.3 billion people, to enforce a complete lockdown, and to urge the citizens to practice social distancing and break the chain to stop the spread. As the world continues to be at war with COVID19, the only way out for us is to stay in.