Nasal Spray NGF Combined With Olfactory Training May Better Improve The Smell Dysfunction Caused By COVID-19

Objective: To explore the efficacy of Olfactory Training(OT)combined with nasal spray Nerve Growth Factor(NGF)in the treatment of persistent olfactory disturbance after COVID-19 infection.Methods: The sample in this study was drawn from 300 adult patients admitted to Sana’a University Education Hospital in Yemen between April 25,2021 and May 3,2021.All participants tested positive for the first time for COVID-19 nucleic acid from nasopharyngeal swabs and were accompanied by mild to moderate fever,cough and difficulty breathing.Patients voluntarily register and sign informed consent.Among them,80 patients had no olfactory dysfunction and 220 patients had olfactory dysfunction.Among them,154 patients recovered spontaneously after 2 weeks.The remaining 66 patients with olfactory dysfunction were divided into two groups,among which 46 patients were treated with nasal spray NGF+OT.20 patients in the control group received nasal spray placebo +OT.Olfactory TDI score tests were performed before treatment,1month after treatment and 3 months after treatment.Results: After one month of treatment,the olfactory score of the experimental group increased by 5.52±3.45 points,and that of the control group increased by 3.45±1.88 points,with significant difference(P=0.003).After 3 months of treatment,the olfactory score of the experimental group was increased by 13.78±6.98 points,and that of the control group was increased by 7.45±2.98 points,which was significantly higher in the experimental group than in the control group(P<0.001).No side effects of nerve growth factors such as allergy,local pain and liver function injury were observed in this study.Conclusion: For olfactory disorders caused by COVID-19 infection,olfactory training combined with nasal spray nerve growth factor treatment can improve smell faster and more significantly than olfactory training alone.Nasal spray nerve growth factor can improve the therapeutic effect of olfactory training,and provide patients with a high efficacy and low cost treatment plan,worthy of further promotion and research.