1. females who are pregnant, planning pregnancy or breastfeeding. 2. concurrent and/or recent involvement in other research or use of another experimental investigational medicinal product that is likely to interfere with the study medication within the last 3 months before study enrolment. 3. serious condition meeting one of the following: i. respiratory distress with respiratory rate \>=40 breaths/min ii. oxygen saturation \<=93% on high-flow oxygen 4. require mechanical invasive or non-invasive ventilation at screening 5. concurrent severe respiratory disease such as asthma, copd and/or ild. 6. any major disorder that in the opinion of the investigator would interfere with the evaluation of the results or constitute a health risk for the study participant. 7. terminal disease and life expectancy \<12 months without covid-19. 8. known allergies to the dornase alfa and excipients. 9. participants who are unable to inhale or exhale orally throughout the entire nebulisation period.

1. females who are pregnant, planning pregnancy or breastfeeding. 2. concurrent and/or recent involvement in other research or use of another experimental investigational medicinal product that is likely to interfere with the study medication within the last 3 months before study enrolment. 3. serious condition meeting one of the following: i. respiratory distress with respiratory rate \>=40 breaths/min ii. oxygen saturation \<=93% on high-flow oxygen 4. require mechanical invasive or non-invasive ventilation at screening 5. concurrent severe respiratory disease such as asthma, copd and/or ild. 6. any major disorder that in the opinion of the investigator would interfere with the evaluation of the results or constitute a health risk for the study participant. 7. terminal disease and life expectancy \<12 months without covid-19. 8. known allergies to the dornase alfa and excipients. 9. participants who are unable to inhale or exhale orally throughout the entire nebulisation period.

females who are pregnant, planning pregnancy or breastfeeding. concurrent and/or recent involvement in other research or use of another experimental investigational medicinal product that is likely to interfere with the study medication within the last 3 months before study enrolment. serious condition meeting one of the following: i. respiratory distress with respiratory rate >=40 breaths/min ii. oxygen saturation <=93% on high-flow oxygen require mechanical invasive or non-invasive ventilation at screening concurrent severe respiratory disease such as asthma, copd and/or ild. any major disorder that in the opinion of the investigator would interfere with the evaluation of the results or constitute a health risk for the study participant. terminal disease and life expectancy <12 months without covid-19. known allergies to the dornase alfa and excipients. participants who are unable to inhale or exhale orally throughout the entire nebulisation period.

females who are pregnant, planning pregnancy or breastfeeding. concurrent and/or recent involvement in other research or use of another experimental investigational medicinal product that is likely to interfere with the study medication within the last 3 months before study enrolment. serious condition meeting one of the following: i. respiratory distress with respiratory rate >=40 breaths/min ii. oxygen saturation <=93% on high-flow oxygen require mechanical invasive or non-invasive ventilation at screening concurrent severe respiratory disease such as asthma, copd and/or ild. any major disorder that in the opinion of the investigator would interfere with the evaluation of the results or constitute a health risk for the study participant. terminal disease and life expectancy <12 months without covid-19. known allergies to the dornase alfa and excipients. participants who are unable to inhale or exhale orally throughout the entire nebulisation period.

1. females who are pregnant, planning pregnancy or breastfeeding. 2. concurrent and/or recent involvement in other research or use of another experimental investigational medicinal product that is likely to interfere with the study medication within the last 3 months before study enrolment. 3. serious condition meeting one of the following: i. respiratory distress with respiratory rate >=40 breaths/min ii. oxygen saturation <=93% on high-flow oxygen 4. require mechanical invasive or non-invasive ventilation at screening 5. concurrent severe respiratory disease such as asthma, copd and/or ild. 6. any major disorder that in the opinion of the investigator would interfere with the evaluation of the results or constitute a health risk for the study participant. 7. terminal disease and life expectancy <12 months without covid-19. 8. known allergies to the dornase alfa and excipients. 9. participants who are unable to inhale or exhale orally throughout the entire nebulisation period.

1. females who are pregnant, planning pregnancy or breastfeeding. 2. concurrent and/or recent involvement in other research or use of another experimental investigational medicinal product that is likely to interfere with the study medication within the last 3 months before study enrolment. 3. serious condition meeting one of the following: i. respiratory distress with respiratory rate >=40 breaths/min ii. oxygen saturation <=93% on high-flow oxygen 4. require mechanical invasive or non-invasive ventilation at screening 5. concurrent severe respiratory disease such as asthma, copd and/or ild. 6. any major disorder that in the opinion of the investigator would interfere with the evaluation of the results or constitute a health risk for the study participant. 7. terminal disease and life expectancy <12 months without covid-19. 8. known allergies to the dornase alfa and excipients. 9. participants who are unable to inhale or exhale orally throughout the entire nebulisation period.