Effectiveness and Safety of Platelet Rich Plasma (PRP) on Persistent Olfactory Dysfunction Related to COVID-19

PRP injections were performed in each olfactory cleft by nasal endoscopy and under local anesthesia, a sniffing stick test was performed before the injection and one month after

"The investigators compare the result of the PRP group to a control group how underwent simple olfactive training for one month.~The control group matched for age, gender and olfactory score at baseline. The patients had a sniffing stick test at the beginning and also after one month of olfactory training."