For those following the less-perfect vaccines (what most of the world will get), a medrxiv study from Chile this week provides some very valuable data: neutralizing antibody levels after natural infection vs 1 or 2 doses inactivated virus or RNA vax.https://www.medrxiv.org/content/10.1101/2021.05.17.21257197v1 …
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5. I speculated ≥4-week interdose intervals and maybe a 3rd dose would be good for Coronavac. That appears true for all inactivated vax. It would get nAb levels above convalescent sera and get efficacy to >90%. But right now supplies are limited.https://twitter.com/michaelzlin/status/1394752409994293249 …
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6. One dose of Coronavac (and likely other inactivated virus vaccines) is ineffective. So it seems you need prime and boost to get decent antibodies with this approach. Ad is better because the virus backbone provides stimulation. RNA probably activates innate immunity pathways.
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7. The RNA 2nd dose effect is pretty massive. No wonder people feel a bit of malaise for 1-2 days. A lot of cytokines are being released. And 1 dose of RNA vaccine indeed is pretty good protection. You predict nAbs ~ natural infection gives ~85% protection, as seen in the trials.
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So to summarize, nAbs correlate with vaccine efficacy, and nAb/efficacy of 2 doses inactivated virus = 1 dose of RNA vaccine (with prefusion spike) = natural infection.
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Interesting; as I had suggested, UAE is going to give third shots of Sinopharm's vaccine (which wasn't in the nAb study above, but seems to be slightly more effective than Sinovac's). Great that the health authorities are on top of it, and being flexible.https://www.scmp.com/news/world/middle-east/article/3133977/coronavirus-uae-offer-third-dose-recipients-chinas-sinopharm …
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Sinopharma data are published! This is the UAE study that served as the basis for WHO approval. 78% efficacy for the HBO2 strain, 73% efficacy for the WIV04 strain overall for symptoms. Not enough data to tell about severe disease protection. https://jamanetwork.com/journals/jama/fullarticle/2780562 …pic.twitter.com/Gk1ZGSPtgZ
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Interestingly just as for Sinovac, there's no noticeable benefit of the first dose. So this older classical approach of inactivated virus and adjuvant really does require the second dose (boost)pic.twitter.com/y5rIZ9zR9C
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Molecular engineering for voltage, viruses, and SARSCoV2. Fan of facts.