One day, the pandemic end up. Scientists don’t know how that final story will play out but a new model offers a teaser: The deadly SARS-CoV-2 may not disappear completely but instead become a cold virus which circulates commonly and causes some mild crumbs.
This model, published January 12 in the magazine Science, based on analyzes of others corona-viruses, most of which cause only mild symptoms in humans. There are six known coronaviruses that affect humans; four of them are coronaviruses that are “endemic” or that circulate regularly among human populations and cause the common cold.
The other two coronaviruses – those that cause severe respiratory syndrome (SARS) and Middle Eastern respiratory syndrome (MERS) – are more lethal, although the former was eradicated years ago and the first end has been largely.
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To create their model, a group of researchers analyzed previously published data on the four milder coronaviruses and found that “disease-inhibiting immunity rapidly declines, but there is an immunity that reduces lifelong diseases, ”the study authors wrote. In other words, people can be infected again and again, but they rarely get a serious illness, lead author Jennie Lavine, a graduate of Emory University in Atlanta, said in a statement.
Almost everyone catches one of these endemic coronaviruses during childhood; and these early diseases provide partial immunity to regenerated adults. “Redemption is possible within a year, but even if it does occur, the symptoms are mild and the virus clears from the body more quickly,” said Lavine.
But similar long-term data on the duration of immunity to the COVID-19-induced novel SARS-CoV-2 coronavirus do not exist. It is unclear how long immunity lasts, whether from vaccines or natural infections, to SARS-CoV-2 in humans; the extent to which vaccines and natural diseases prevent the spread or reduce the severity of the disease is also unknown.
Some people have been regenerated with SARS-CoV-2, Live science previously reported. But these cases have been rare and most of these people have had a milder illness a second time, according to the study.
The model assumes that immunity to SARS-CoV-2 will work similarly to these other endemic coronaviruses, Lavine said. And one of the main conclusions of the model is that, for pre-existing coronaviruses, the severity of the disease during the endemic phase is directly related to the severity of the disease when it affects children. Unlike the novel coronavirus, almost no one comes across those who circulate widely at first as an adult. But “we don’t know for sure what it would be like if someone got one of the other coronaviruses for the first time as an adult, rather than as a child,” she said. If they did, they could become worse.
Their model suggests that if SARS-CoV-2 becomes endemic, and future generations are largely exposed during childhood, the virus may not be “more brutal than the common cold,”. ”Wrote the authors. Once endemic, the ratio of the infectious death of the virus, or the number of deaths compared to those infected, falls below the level of seasonal flu, wrote the authors.
That’s because COVID-19 infections don’t affect children as much and mortality is usually low in children, so this baseline depth should predict how bad they are. SARS-CoV-2 is at the endemic stage. But if SARS-CoV-2 adversely affected children, as is the case with the virus that causes MERS, then even at the endemic stage, a relatively high number of people may have died, the authors were predicting.
If this model is true, it is just as the world reaches the endemic stage: Faster virus spread leads to faster transition as humans benefit herd immunity, but more deaths will result. Vaccines are a safer way to achieve this protection and once widely available will accelerate the transition to a potentially endemic stage – a stage at which a corona box can be handled with a box. of Kleenex, other than ventilators and locks.
First published on Living Science.