Here’s some encouraging news for once regarding SARS-CoV-2 infections: A study of young adults for whom prepandemic spirometry data were available showed that COVID-19 did not have a significant impact on lung function, even among patients with asthma.
Among 853 Swedish men and women (mean age, 22 years) who were part of a birth cohort study, there were no significant differences in either forced expiratory volume in 1 second (FEV1) or in the ratio of FEV1 to forced vital capacity, reported Ida Mogensen, MD, PhD, a postdoctoral fellow at the Karolinska Institute in Stockholm.
“We found no effect of COVID-19 on spirometric lung function in generally healthy adults,” she said in an oral abstract presented at the European Respiratory Society 2021 International Congress.
The findings echo those of a small study that involved 73 children and adolescents with COVID-19 and 45 uninfected control persons. The investigators in that study, which was also presented at ERS 2021, found that there were no significant differences in the frequency of abnormal pulmonary function measures between case patients and control patients (abstract OA1303).
“The findings from these two studies provide important reassurance about the impact of COVID infection on lung function in children and young adults,” commented Anita Simonds, MD, an honorary consultant in respiratory and sleep medicine at the Royal Brompton Hospital, London.
“We know already that this group is less likely to suffer severe illness if they contract the virus, and these studies, which importantly include comparator groups without COVID-19, show that they are also less likely to suffer long-term consequences with respect to lung function,” she said. Dr. Simonds was not involved in either study.
Young adult study
Dr. Mogenson and colleagues assessed data on 853 participants in the BAMSE Project, a prospective birth cohort study that included 4,089 children born in Stockholm from 1994 to 1996. Of the participants, 147 had asthma. They have been regularly followed with questionnaires on respiratory symptoms and medications. In addition, at 8 and 16 years’ follow-up, spirometry measures and fractional exhaled nitric oxide (FeNO) levels were assessed, allergic sensitization tests were administered, and blood eosinophil levels were measured.
In 2020 and 2021, during the pandemic, the participants underwent spirometry testing and were assessed for antibodies against SARS-CoV-2, and they self-reported use of inhaled corticosteroids.
The investigators defined asthma as any physician diagnosis and asthma symptoms and/or asthma medication use within the previous year. Participants were determined to be COVID-19 seropositive if they had IgG antibodies to the SARS-CoV-2 spike greater than 25.09 AU/mL, IgM antibodies greater than 14.42 AU/mL, or IgA antibodies greater than 2.61 AU/mL, as measured with enzyme-linked immunosorbent assay.
Participants who had been vaccinated against COVID-19 were excluded.
No significant decreases
A total of 243 participants, including 38 with asthma, were seropositive for SARS-CoV-2 antibodies. The mean change in lung function from before the pandemic to the study end date during the pandemic were not significantly different between seropositive participants and seronegative participants or IgM-positive participants and seronegative participants.
Similarly, there were no significant differences in lung function between seropositive and seronegative participants in an analysis that was adjusted for sex, body mass index, smoking status, or prepandemic lung function.
Although there was a trend toward slightly lower function among seropositive participants with asthma in comparison with seronegative patients with asthma, it was not statistically significant, Dr. Mogenson said.
There were also no significant decreases in lung function from the prepandemic measure to the present in any of the inflammatory parameters, including blood eosinophil levels, FeNO, allergic sensitization, or inhaled corticosteroid use.
Potential misclassification
In the question-and-answer period that followed the presentation, session comoderator Sam Bayat, MD, PhD, from the University of Grenoble (France), who was not involved in the study, noted that “some subjects can have positive serology without any symptoms, while others can have symptomatic disease and a couple of months later they have negative serology.”
He asked Dr. Mogenson whether they had included in their study participants with symptomatic COVID-19 and whether that would change the findings.
“We did not have access to RNA testing, so we only had serology, and of course some participants could be wrongly classified to have disease – probably around 15%,” she acknowledged.
She noted that there were no significant changes in lung function among patients who reported having respiratory symptoms.
The study was funded by the Swedish Research Council, the Swedish Heart-Lung Foundation, the Swedish Research Council for Health, Working Life and Welfare, the Karolinska Institutet, Formas, the European Research Council, and Region Stockholm. Dr. Mogenson, Dr. Simonds, and Dr. Bayat disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.