Coronavirus infection (COVID-19) is now a part of everyone’s life, and its history is being rewritten all the time. This section provides a summary of the narrative thus far, including where SARS-CoV-2 may have originated, how it relates to other viruses that cause serious respiratory disease and some of the medicines and vaccines now being researched to battle it. The World Health Organization (WHO) was publicly warned of a cluster of pneumonia cases in Wuhan City, home to 11 million people and the cultural and economic centre of central China, on December 31, 2019. By the 5th of January, 59 cases had been identified, none of which had resulted in death. WHO learned of 282 confirmed cases ten days later, four of which were in Japan, South Korea, and Thailand, In Wuhan, six people died, 51 people were seriously ill, and 12 people were in serious condition. The virus in question was discovered on January 7th, and its genome was published on January 12th. A new coronavirus, SARS-CoV-2, was responsible for the severe acute respiratory disease that became known as COVID-19. The rest is history, albeit history that is continuously being rewritten: Globally, as of 11 June 2021, there have been 174,502,686 confirmed cases of COVID-19, including 3,770,361 deaths, reported to WHO. According to phylogenetic study, SARS-CoV-2 originated in animals, most likely bats, then spread to other species before infecting people at Huanan wet market in Wuhan city. There is some evidence that the intermediate vector was a pangolin, a nocturnal anteater that was illegally imported for its flesh. This animal was indeed infected with a coronavirus that was very similar to SARS-CoV-2, but differs in a key region that determines viral infectivity and host range. It’s possible that the virus infected humans and then mutated to acquire the characteristics that allowed it to spread so quickly through adaptation as it infected more people. The coronavirus SARS-CoV-2 is not the first to produce human respiratory illness outbreaks. So far, six more have been discovered, all of which are thought to have originated in animals. The four coronaviruses that are currently endemic in humans cause 10–15 % of common colds, peaking in temperate areas between December and April. NL63 and 229E are thought to have originated in bats, whereas OC43 and HKU1 are believed to have originated in rodents.
SARS-CoV-2 appeared as a new virus against which humans had no immunity; it spreads swiftly, has a high fatality rate, and can overwhelm healthcare systems’ ability to treat the sickest patients. However, it is not incomparable: commonalities with other coronaviruses, as well as recent outbreaks, imply that infection control methods are well-practised, and current technology may be used to accelerate the development of novel vaccines and therapies.
Each of them causes very minor symptoms, while OC43 is related to a bovine coronavirus that may have triggered a pandemic at the end of the nineteenth century. A serious disease has been caused by two non-endemic coronaviruses. SARS-CoV was the first to be identified, first appearing in November 2002 in China (though it was unknown at the time) and coming to the attention of WHO early in 2003 in Viet Nam. By July, the outbreak was somewhat over, and the final cases in China were recorded in April 2004. This virus caused Severe Acute Respiratory Syndrome (SARS), a flu-like disease characterised by diarrhoea. In two weeks, it might proceed to pneumonia and respiratory failure, and 25% of those infected needed intensive care. There were a total of 8098 cases and 774 fatalities reported. SARS-CoV is thought to have originated in horseshoe bats and was transmitted to humans via palm civet cats, which were trafficked in China for their meat. Middle Eastern Respiratory Syndrome was the second significant coronavirus illness (MERS). In 2012, the MERS-CoV virus was discovered to be the source of a fatal disease in Saudi Arabia. It expanded to 27 different nations. Unlike SARS, MERS is still a concern, with 2494 illnesses reported as of November 2019, 858 of whom were dead. MERS, like SARS, causes a flu-like disease with symptoms ranging from moderate to severe pneumonia, acute respiratory distress syndrome, septic shock, and multiorgan failure. About one-quarter of those infected also have diarrhoea. MERS-CoV is suspected to have spread to people by dromedary camels, which seem to be a reservoir in several Middle Eastern countries. Although the source species is unknown, bats are the most plausible contenders. SARS-CoV-2 resembles the bat wild virus more closely than either SARS-CoV or MERSCoV, implying that it is a novel coronavirus in humans. The coronavirus spike protein, which connects the virus to the target receptor and facilitates cell entry, requires six amino acids, of which SARS-CoV-2 happens to share only one with SARS-CoV. This spike protein has a strong affinity for the host receptor in humans, angiotensin-converting enzyme 2 (ACE2) (and many other species, including pigs, primates and cats) The second significant structural difference between SARS-CoV and other viruses is a unique component of the spike protein that determines viral infectivity and host range. The fast spread of COVID-19 in humans may have been caused by a mutation of this characteristic during human infection. Since the SARSCoV-2 virus first emerged in humans, a lot of shreds of evidence of diverse mutations have been discovered. SARS-CoV-2 appeared as a new virus against which humans had no immunity; it spreads swiftly, has a high fatality rate, and can overwhelm healthcare systems’ ability to treat the sickest patients. However, it is not incomparable: commonalities with other coronaviruses, as well as recent outbreaks, imply that infection control methods are well-practised, and current technology may be used to accelerate the development of novel vaccines and therapies.
( The author is pursuing M.Sc Microbiology at P. G Department of Microbiology at Kashmir University. Views are his own)
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