We can look back to SARS CoV1 and MERS (Middle Eastern Respiratory Virus) and study their long term effects on infected individuals. Many acutely infected patients dealt with long term effects. We should not be surprised at COVID 19 leaving long hauler symptoms. For those in functional medicine, we have been dealing with post-viral conditions for years.
O’Sullivan, Oliver. “Long-term sequelae following previous coronavirus epidemics.” Clinical medicine (London, England) vol. 21,1 (2021): e68-e70. doi:10.7861/clinmed.2020-0204