April 16, 2020 05:31PM | Registered: 7 years ago Posts: 16,078 |
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Ekern55
Exposure might be the only path to immunity.
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. [www.technologyreview.com]
First, even assuming people who get sick do become immune, we have no idea how long they’ll stay immune. (With some coronaviruses, as well as with ordinary flu, immunity lasts less than a year.) Second, assuming they stay immune, we have no idea how long it would take to reach herd immunity.... it’s still not clear that we’d reach natural herd immunity sooner than we can develop a vaccine or a cure. Either way, we still have to keep the infection rate down in the meantime to a level that doesn’t collapse the hospital system....
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. [www.businessinsider.com]
The US is not close to achieving herd immunity for the coronavirus, experts say. To put the virus in decline, at least 50% of the population would have to be immune. Only an estimated 2-3% of Americans have recovered from COVID-19 so far.
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. [www.sciencefocus.com]
we don’t know how long those who are infected are subsequently immune for. Some other viruses in the coronavirus family, such as those that cause the common cold, only provide immunity for around three months or so. “There’s evidence for short-term immunity [after contracting COVID-19],” says Rossman, “but we just don’t have the data yet to know whether it provides long-term immunity.”
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. [www.scientificamerican.com]
... immunity functions on a continuum. With some pathogens, such as the varicella-zoster virus (which causes chicken pox), infection confers near-universal, long-lasting resistance. Natural infection with Clostridium tetani, the bacterium that causes tetanus, on the other hand, offers no protection—and even people getting vaccinated for it require regular booster shots. On the extreme end of this spectrum, individuals infected with HIV often have large amounts of antibodies that do nothing to prevent or clear the disease.
At this early stage of understanding the new coronavirus, it is unclear where COVID-19 falls on the immunity spectrum. Although most people with SARS-CoV-2 seem to produce antibodies, “we simply don’t know yet what it takes to be effectively protected from this infection,” says Dawn Bowdish, a professor of pathology and molecular medicine and Canada Research Chair in Aging and Immunity at McMaster University in Ontario. Researchers are scrambling to answer two questions: How long do SARS-CoV-2 antibodies stick around? And do they protect against reinfection?
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. [thehill.com]
herd immunity is almost only talked about in the context of vaccines. “You don’t rely on the very deadly infectious agent to create an immune population,” says virologist Akiko Iwasaki at the Yale School of Medicine to the Atlantic. That’s because a large proportion of the population would need to get infected, and the way the pandemic is going many would die.
We also don’t know whether COVID-19 survivors are immune to the virus, SARS-CoV-2, after they’ve recovered, and, if they are, for how long.