A reduced diffusion capacity in the pulmonary function of patients who have experienced severe coronavirus disease 2019 (COVID-19) has been widely reported, which has contributed to some of the severe symptoms associated with COVID-19. Furthermore, the majority of hospitalized patients with COVID-19 have suffered from restrictive lung function impairment.
Study: Lung function before and after COVID-19 in young adults: a population-based study. Image Credit: KZenon / Shutterstock.com
Scientists have expressed difficulty in assessing the impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on lung function with spirometry as a result of the great variability in lung function that exists between individuals.
Several studies have indicated that people with higher than average lung function showed significant decline post-COVID-19. Importantly, these studies have reported that pulmonary abnormalities that occurred during severe COVID-19 improved after virus clearance.
Recently, many studies have reported post-COVID symptoms, irrespective of disease severity. However, not much evidence is available regarding the degree of impairment of lung function in young adults who were not severely infected by SARS-CoV-2.
Although non-severe asthma patients are not at risk of contracting severe COVID-19 or hospitalization, it is important to determine whether pre-existing asthma influences lung function changes related to mild or moderate SARS-CoV-2 infection.
About the study
In a new Journal of Allergy and Clinical Immunology: Global study, researchers evaluate whether SARS-CoV-2 infection has a negative impact on lung function in young adults who experienced mild to moderate COVID-19. In this study, the researchers further analyzed if pre-existing conditions, such as asthma and allergic sensitization, or the use of inhaled corticosteroids (ICS), affected the pulmonary function of the study cohort.
In this study, candidates from the population-based cohort Barn, Allergi, Miljö, Stockholm, Epidemiologi (BAMSE) were evaluated before (2016-2019) and after the onset of the COVID-19 pandemic (2020-2021). The researchers obtained seropositivity data based on serum levels of SARS-CoV-2 receptor-binding domain-specific immunoglobulin (Ig) G, IgM, and/or IgA.
The mean change in the lung function was recorded in percent of predicted (pp) from before to after the onset of the COVID-19 pandemic. The serological data obtained before and after the onset of the pandemic were compared. Changes in the lung function in seropositive candidates were also analyzed in accordance with allergic sensitization and self-reported ICS use.
The authors did not observe any evidence of COVID-19-associated lung function impairments in young adults with or without asthma. In addition, no connection between allergic sensitization or ICS-use and lung function change was observed in COVID-19 seropositive patients.
A small number of participants with asthma possessing IgM antibodies exhibited a possible spirometric worsening as compared to the seronegative group with asthma, which might be due to an exacerbation of asthma in proximity to the infection.
Previous studies have shown that viral respiratory infections are common triggers of asthma exacerbations. These studies have also revealed that children infected with SARS-CoV-2 did not suffer any damage to their lung function.
A small number of adults with COVID-19 experienced asthma exacerbations; however, allergic sensitization did not affect lung function in the seropositive group. The use of ICS also did not affect COVID-19 outcomes in the study cohort.
Strengths and limitations
A key strength of the current study is the availability and utilization of lung function measures that were recorded before and after the COVID-19 pandemic. This data possesses the potential to detect minor changes in lung function among individuals with confirmed COVID-19 and compare the result with seronegative individuals. In the study cohort, the majority of the participants had mild disease, which reflected the disease manifestation in young children infected with SARS-CoV-2.
One of the key limitations of this study is the lack of information about the total lung capacity of the participants. Although previous studies related to normal spirometry suggested restrictive impairment to be unlikely, the lack of data in the current study did not permit the authors to make a strong conclusion about restrictive lung function impairment.
Another limitation of the study is the inclusion of seropositivity as a marker for previous COVID-19, as individuals with low or absent antibody responses were not considered. There is a high possibility of reduced antibody levels among individuals who were infected early in the pandemic. The authors also indicated the possibility of misclassification of some participants with previous COVID-19, which presents the possibility of biased results.
The current study revealed that young adults with mild to moderate COVID-19 do not suffer from impaired spirometric lung function. Additionally, no evidence was found to suggest that participants with asthma suffered long-term lung function damage. Furthermore, the current study revealed that allergic sensitization or recent ICS use had no significant impact on the lung function of seropositive participants.
- Mogensen, I., Hailberg, J., Bjorkander, S., et al. (2022) Lung function before and after COVID-19 in young adults: a population-based study. Journal of Allergy and Clinical Immunology: Global. doi:10.1016/j.jacig.2022.03.001.