This first-in-human study is designed to evaluate the safety, tolerability, pharmacokinetics and target engagement of ETH47 in healthy participants following single intranasal and single inhaled administration

Inclusion Criteria:

1. Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF), restriction handbook and in this protocol.

2. Participants who are overtly healthy, as determined by screening assessments and the Investigator's judgement, aged ≥18 and ≤55 years at the time of obtaining informed consent.

3. Body mass index of 18.5 to 32 kg/m2 (inclusive).

4. Participants must agree to use contraception methods.

5. Parts B only: participants must be able to perform reliable and reproducible pulmonary function tests and meet the following criteria at screening:

   1. Forced expiratory volume in one second (FEV1) ≥80 % predicted by third National Health and Nutrition Examination Survey standards, and
   2. Change in FEV1 and forced vital capacity <200 mL, 15 minutes after 4 puffs of inhaled short-acting beta 2-agonists.

Major Exclusion Criteria:

1. History or presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal, neuropsychiatric, autoimmune, or immunosuppressive disorders which, in the Investigator's judgement, puts the participant at risk due to participation in the trial, may influence the results of the trial, or the subject's ability to participate in the trial.

2. Signs or symptoms of upper or lower respiratory tract infection within 2 weeks of randomisation.

3. Participants who are SARS-CoV-2 positive.

4. Known or positive laboratory results at screening for human immunodeficiency virus (HIV) infection, hepatitis B or hepatitis C.

5. Any malignancy except for the following:

   1. Adequately treated basal cell carcinoma or
   2. History of any other cancer where the disease-free period is ≥5 years.

6. The evidence of any other active or chronic disease following a detailed medical and surgical history, a complete physical examination including vital signs, haematology, blood chemistry, serology, and urinalysis.