Tracking the next pandemic: Avian Flu Talk |
Omicron didnt evolve from.Beta or Delta |
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KiwiMum
Chief Moderator Joined: May 29 2013 Status: Offline Points: 29680 |
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Posted: January 06 2022 at 7:39pm |
That is so interesting. I wonder where it went? In Susan Scott's book Return of the Black Death: the world's greatest serial killer, she shows how the pneumonic plague of the middle ages kept disappearing and then returning 20 or so years later, and she asks the question where did it go? She concludes that it must have an animal repository to exist in between bouts of plague in people and if that's the case then can we expect it to return? It's a great book, definitely worth the read. |
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Those who got it wrong, for whatever reason, may feel defensive and retrench into a position that doesn’t accord with the facts.
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Hazelpad
Adviser Group Joined: September 09 2014 Status: Offline Points: 6910 |
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Interesting one from Dr Campbell tonight ( link below and I looked over papers also). In summary he presented the following. Omicron didnt evolve from Delta or Beta. It split off from the original Wuhan strain around mid 2020. It then disappeared for 18months. During this time it accumulated mutations at a much faster rate than normal ( 1.5 mutations a month instead of usual 0.5 mutations indicating it was under strong selective pressure. So ..where did it go for 18 months and what allowed its mutation rate to be so high ? 3 interesting theories but evidence points to 3rd theory. 1) It was circulating and mutating in a population which had no PCR testing, so was undetected but was infecting people and changing. ( this however doesnt explain it's unusual high mutation rate) 2) It was in a chronically infected individual where it quietly gathered mutations. For example a human with HIV cant clear the virus, it lives and divides and mutates in that person continuously. The person acts as an incubator. This though still doesnt explain its high mutation rate. 3) In mid 2020 omicron predecessor left the human population and jumped into mice. There it underwent a faster mutation rate ( common in animals), the mutations were especially within the spike protein and it is shown to have adapted to fit the slightly different Mice ACE2 receptors perfectly. 18 months later It jumped back to humans. Mice ACE2 receptors are more like our upper airways and not like our lower airways. This meant the mutated virus now adapted to mice, could accumulate in huge numbers in humans upper but not lower airways. Here it is close to the point of exit ( nose and mouth) so could be more infectious than Beta or Delta. Also avoiding the lower airways could be less pathogenic. So Dr Campbell finishes by saying....was it just luck that 1) Omicron escapes vaccine, out competes pathogenic delta, and infect and immunised us without causing severe disease.( data not complete yet but so far in Scotland indications are it is less severe). ( also unknown if omicron can prevent reinfection with delta) 2) Are we also lucky that it was mice it jumped into and not another animal like camel. Camels Ace2 receptors are like our lower airways. So it could have emerged adapted to more efficiently infect our lower airways and cause a MERS like illness which is 35%CFR. ( lower airways is also closer to blood so becomes a blood virus as well as a lower respiratory.) Anyway I found it interesting. Must start telling my cats "Mice are Nice" and to stop drowning them. My cats hold them under the water with their paws... it's a trait of their breed...crazy cats. Hz x |
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