Post acute sequelae of COVID-19, or PASC, is the term to describe survivors of severe COVID-19 who suffer long-term symptoms like chronic fatigue or a loss of taste and smell longer than four weeks after recovery.
Experts are yet unsure why some COVID-19 survivors have PASC and why others don't, but post-viral syndromes are not new: After the 1918 flu pandemic, some survivors of that flu developed Parkinson's.
However, some survivors with PASC, like Darell Jones, have reported feeling those long-term symptoms ease shortly after getting a COVID-19 vaccine.
Jones caught COVID-19 in March 2020, recovered by May, but still has trouble breathing and has not regained his sense of smell or taste. He said he felt better within 30 minutes of getting the vaccine.
"I'm hoping I'm going to get my taste and smell back so I can taste the ribs and all the pizza that I like," he said.
Dr. Stephen Feagins, chief clinical officer for Mercy Health and Hamilton County, said the reason some survivors feel better is just as unclear as what causes PASC in some COVID-19 survivors.
Feagins said he theorizes lyme disease could be a model that leads to understanding PASC better, but experts have several other theories, ranging from PASC as a partially resolved infection to the symptoms being the result of a body's overreaction to the virus.
"We know that the loss of taste and smell are partially neurological and partially antibody-induced," said Feagins. "And that's as far as we know."