same as the flu, immunity to one variant or serotype doesn’t mean you’ll have the same level of immunity to a stronger variant next year. Alpha Wuhan had a days to symptoms of 7-10, with a crash on day 10. Plenty of time to prime the immune system. Delta has 3-4 days to symptoms, with a viral load that is up to 1000x that of the original virus which means it’s been hammer down since hour 1. Meaning a person gets sicker, and are hospitalized faster, with less time to self-medicate and a higher risk of organ damage and long-covid.
White Paper - 23.3% of recovered have long covid
https://s3.amazonaws.com/media2.fairhealth.org/whitepaper/asset/A%20Detailed%20Study%20of%20Patients%20with%20Long-Haul%20COVID—An%20Analysis%20of%20Private%20Healthcare%20Claims—A%20FAIR%20Health%20White%20Paper.pdf
Pre-Print - Brain imaging before and after COVID-19 in UK Biobank
https://www.medrxiv.org/content/10.1101/2021.06.11.21258690v1
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