Exposure to airway irritants and the risk of permanent of respiratory impairment after Covid-19

Background

The knowledge about the long-term respiratory effects after Covid-19 is limited. Respiratory problems are common and reported by about 30% a 3 months after discharge from hospital, but is also prevalent in those who not have been hospitalized.

Covid-19 particularly affect small airways. The virus specifically attacks type II cells in the alvoli that produce surfactant, that covers the alveoli and constitute the first-line defence against inhaled material. Surfactant function is disrupted after infection and how quickly it resumes after infection is unclear.

Small airways are known as the "quiet zone of the lung" as dysfunction only give rise to discrete symptoms, and is difficult to detect by spirometry at an early stage.

The hypothesis of the current project is that subjects who have had Covid-19 are particularly susceptible to exposure to respiratory irritants at work. This type of exposure may maintain inflammation in small airways, which in the long run can lead to permanent lung damage, such as lung fibrosis. Aims

The overall air is to examine if workers exposed to respiratory irritants are more susceptible to exposure after Covid-19? To achieve this we will: • Assess if the barrier function in small airways is affected after recovering from the acute phase of Covid-19? • Examine if there are physiological changes in small airways after Covid-19

We will also try to identify an easy method to identify subjects with small airway dysfunction after Covid-19, suited for occupational health services? Work plan

We want to establish a cohort of workers who have had Covid-19, half of whom exposed to respiratory irritants at work. We will follow the cohort prospectively and examine them with state-of-the art pulmonary physiological methods, and non-invasively sample surfactant from small airways. By chemical analyses, we will examine whether the barrier function in small airways is affected and if there are signs of inflammation.

The subjects will be followed with a questionnaire after 6 months, then a renewed clinical examination after 1-year (not incl i current application) Relevance

Covid-19 is a novel pandemic and its long lasting effects of the airways are unknown. An increased risk for the development of restrictive lung disease and lung-fibrosis have been reported. If workers occupationally exposed to airway irritants are particular susceptible is not known, but seems plausible, and need to be carefully examinied.