My Health 2 years into the pandemic, what have we learned? Written by Katharine Lang on March 16, 2022 — Fact checked by Alexandra Sanfins, Ph.D. | www.medicalnewstoday.com Before March 2020, many people saw pandemics as a thing of the past. Then Both of these coronaviruses caused diseases with high fatality rates, but it was came COVID-19. Scientists still do not know exactly where the virus that caused possible to contain the spread before they reached pandemic levels. So, were we it — SARS-CoV-2 — came from, but it soon reached almost every country world- ready for the next coronavirus? wide. Over 2 years, the virus has evolved, producing several variants. In this Special Feature, we look at the evolution of SARS-CoV-2 and ask what lessons scientists have learned.
The origins of SARS-CoV-2
In late 2019, there was a sudden increasein pneumonia cases in central China. Experts believe that SARSTrusted Source came from bats and that MERSTrustBy January 7, scientists had identified and isolated a previously unknown coro- ed Source crossed over to people from camels. However, for SARS-CoV-2, researchers have not all agreed on any of the many existing theories. navirus, now designated SARS-CoV-2. On March 11, 2020, the World Health Organization (WHO)Trusted Source declared COVID-19 a pandemic.
At first, people thought that SARS-CoV-2 might have come directly from batsTrusted Source. Scientists discounted that theory, though, as the spike protein on SARS-CoV-2 is very different from that on the coronaviruses present in bats.
Now, 2 years on, authorities have recorded more than 458 million cases of COVID-19, the disease resulting from SARS-CoV-2. The disease has also played Now, researchers think it is likely that the virus originated in bats but had an intermediate host between bats and people. A recent study — which has not yet a role in the deaths of more than 6 million people. undergone peer review — suggests that live mammals for sale at the Huanan However, the actual death toll may well be far higher than 6 million. According Seafood Wholesale Market in Wuhan, the epicenter of early cases, might have to a recent paper in The Lancet, the actual death toll may be at least three times been the intermediate host. that. Another recent study — also yet to undergo peer review — that analyzed the evolution of SARS-CoV-2 suggests that “SARS-CoV-2 emergence likely resulted from multiple zoonotic events.” The researchers do not suggest what the intermediate animal hosts might be. On December 29, 2019, experts linked four cases of pneumonia of unknown etiologyTrusted Source to the Huanan Seafood Wholesale Market in Wuhan, Alternatively, did SARS-CoV-2 escape from a laboratory in Wuhan, as some central China. media outletsTrusted Source have suggested? The WHOTrusted Source has dismissed this theory as “extremely unlikely.” On January 7, 2020, researchers isolated the causative agent, SARS-CoV-2, and on January 10, they sequenced its genome. So, there is still uncertainty about the origins of SARS-CoV-2. And this may be due, in some measure, to a lack of international cooperation, as Prof. Jonathan By January 2, 2020, doctors had confirmed that 41 people in a Wuhan hospital Stoye, a virologist at the Francis Crick Institute in London, United Kingdom, with severe respiratory illness had a SARS-CoV-2 infection. Of these individu- told Medical News Today. als, 27 had had exposure to the seafood market. In his opinion, “one mistake was to start pointing fingers at China and blaming them for the origin of this virus. I think that, naturally, led to pushback from the Chinese [authorities].”
The first cases
Other human coronaviruses
Many coronaviruses exist, affecting both animals and people. Most cause infec- He added: “I absolutely believe in natural origins [of SARS-CoV-2], but the Chitions with mild to moderate symptoms in the upper respiratory tract, such as nese [authorities] could have made things easier if they’d opened up their books colds. straightaway. They weren’t going to do that when they were being accused of being responsible [for the virus].” In recent years, two coronaviruses — SARS-CoV and MERS-CoVTrusted Source — have caused more severe disease. SARS-CoV, which scientists identified in November 2002, was responsible for severe acute respiratory syndrome (SARS), which emerged in Asia. The Centers for Disease Control and Prevention (CDC) Trusted Source note that of the 8,096 people with a known SARS infection, 774 died. There have been no reported cases since 2004. Scientists first identified Middle East Respiratory Syndrome (MERS), the disease that MERS-CoV-2 causes, in 2012 in Saudi Arabia. The mortality rate for MERS is high — of every 10 people with the infection, three or fourTrusted Source die. There continue to be occasional, localized outbreaks of this disease.
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TT 145 | MAR 22nd - 28th | 2022
