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One day the pandemic will end. Scientists don’t know how this finale will play out, but a new model offers a teaser: the deadly SARS-CoV-2 may not go away entirely but become a commonly circulating cold virus that causes only mild sniffles.
This model, published on January 12 in the journal Science, is based on analyzes of other coronavirus, the majority of which cause only mild symptoms in humans. There are six known coronaviruses that infect humans; four are “endemic” or regularly circulating coronaviruses among human populations and causing colds.
The other two coronaviruses – those that cause Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) – are deadlier, although the former was wiped out years ago and the latter was largely contained.
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To create their model, a group of researchers analyzed previously published data on the four most benign coronaviruses and found that “anti-infection immunity wanes rapidly, but disease-reducing immunity lasts a long time,” wrote the authors in the study. In other words, people can get infected over and over again, but rarely get serious illness, lead author Jennie Lavine, postdoctoral researcher at Emory University in Atlanta, said in a press release.
Almost everyone gets one of these endemic coronaviruses in childhood; and these early infections confer partial immunity to adults who are re-infected. “Reinfection is possible within a year, but even if it does occur, the symptoms are mild and the virus is cleared from the body more quickly,” Lavine said.
But there is no similar long-term data on the duration of immunity for the novel coronavirus SARS-CoV-2 that causes COVID-19. It is not known how long immunity, whether from vaccines or from natural infection, against SARS-CoV-2 will last in humans; it is also not known to what extent vaccines and natural infections will limit transmission or reduce the severity of the disease.
Some people have already been re-infected with SARS-CoV-2, Previously reported Live Science. But those cases were rare and most of those people had milder illness the second time around, according to the study.
The model assumes that immunity to SARS-CoV-2 will work the same as these other endemic coronaviruses, Lavine said. And one of the main conclusions of the model is that, for existing coronaviruses, the severity of infection during the endemic phase is directly related to the severity of the disease when it infects children. Unlike the new coronavirus, hardly anyone meets those who circulate widely first in adulthood. But “we don’t really know 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. It is possible that if they did, they would suffer from a more serious illness.
Their model predicts that if SARS-CoV-2 becomes endemic and future generations are primarily exposed during childhood, the virus “may not be more virulent than the common cold,” the authors wrote. Once endemic, the death rate from infection with the virus, or the number of people who die compared to those infected, will drop below that of the virus. seasonal flu, wrote the authors.
This is because children are generally less severely affected by COVID-19 infections and mortality is generally low in children, so this baseline severity should predict the severity of SARS-CoV-2 in its phase. endemic. But if SARS-CoV-2 severely affected children, as is the case with the virus that causes MERS, then even during the endemic phase a relatively high number of people could die, the authors predicted.
If this pattern is true, how exactly the world reaches the endemic phase will still be up to us: faster spread of the virus will lead to a faster transition as people win. collective immunity, but it will lead to more deaths. Vaccines are a safer way to achieve such immunity and, once widely available, will also speed up the transition to a possible endemic phase – a phase in which the coronavirus can be approached with a box of Kleenex, rather than ventilators. and interlocks.
Originally posted on Live Science.
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