inclusion criteria: 1. previous diagnosis of covid-19 infection; 2. olfactory function was normal in the past, and the olfactory function decreased due to covid-19 infection, which has occurred more than 2 weeks; 3. olfactory function test score: tdi ≤ 30; 4.18 ≤ age ≤ 55 years old; 5.good overall physical condition, without other diseases that may affect the test; 6. no active infection, such as uncontrolled pneumonia; 7. women with reproductive potential and sexually active men agree to use acceptable and effective contraceptive methods.

inclusion criteria: 1. previous diagnosis of covid-19 infection; 2. olfactory function was normal in the past, and the olfactory function decreased due to covid-19 infection, which has occurred more than 2 weeks; 3. olfactory function test score: tdi ≤ 30; 4.18 ≤ age ≤ 55 years old; 5.good overall physical condition, without other diseases that may affect the test; 6. no active infection, such as uncontrolled pneumonia; 7. women with reproductive potential and sexually active men agree to use acceptable and effective contraceptive methods.

inclusion criteria: previous diagnosis of covid-19 infection olfactory function was normal in the past, and the olfactory function decreased due to covid-19 infection, which has occurred more than 2 weeks; olfactory function test score: tdi ≤ 30; 4.18 ≤ age ≤ 55 years old; 5.good overall physical condition, without other diseases that may affect the test; 6. no active infection, such as uncontrolled pneumonia; 7. women with reproductive potential and sexually active men agree to use acceptable and effective contraceptive methods.

inclusion criteria: previous diagnosis of covid-19 infection olfactory function was normal in the past, and the olfactory function decreased due to covid-19 infection, which has occurred more than 2 weeks; olfactory function test score: tdi ≤ 30; 4.18 ≤ age ≤ 55 years old; 5.good overall physical condition, without other diseases that may affect the test; 6. no active infection, such as uncontrolled pneumonia; 7. women with reproductive potential and sexually active men agree to use acceptable and effective contraceptive methods.