COVID-19 infection does not appear to affect the lung function of young adults according to two studies presented at this year’s European Respiratory Society virtual Congress (ERS 2021).
In one study that followed up 661 young people before and after the pandemic, researchers at the Karolinska Institute, Stockholm, Sweden, found no significant deterioration in lung function, even in individuals with asthma.
A second study presented at the congress also showed that the lung function in children and adolescents was also unimpaired after COVID-19 infection, except for children who experienced a severe infection.
In the first study, researchers analysed data from young people with an average age 22 years who were enrolled in a long term follow up starting between 2016 and 2019. The examinations at the COVID-19 follow-up took place between October 2020 and May 2021. Collected data included measurements of lung function, inflammation and white blood cells called eosinophils, which are part of the immune system.
More than a quarter (27%) of participants had antibodies against SARS-CoV-2 indicating they had been infected. The researchers measured FEV1, FVC, and FEV1/FVC ratio. They calculated the changes in lung function between the period before the pandemic and during the pandemic. Then they compared the percentage change with participants who had not been infected.
The analysis showed similar lung function irrespective of COVID-19 history, said lead investigator Dr Ida Mogensen.
“When we included 123 participants with asthma in the analysis, the 24% who had had COVID-19 tended towards having a slightly lower lung function, but this was not statistically significant,” she told the meeting.
There was no difference in lung function among patients who had had COVID-19 with respect to eosinophils, indicators of inflammation, allergy responses or use of inhaled corticosteroids.
“These results are reassuring for young adults. However, we will continue to analyse data from more people. In particular, we want to look more closely at people with asthma as the group in this study was fairly small. We are also curious as to whether the length of time after the infection is important, as well as the severity of disease and symptoms,” said Dr Mogensen.
Similarly, a study conducted in Germany found no long-term effects of COVID-19 infection in 73 children and adolescents aged between five and 18 years, apart from those with severe infection.
In the study, children had lung function tests between two weeks and six months following COVID-19 infection and compared the results with a control group of 45 children who had not been infected with the coronavirus but may have had some other infection.
Nineteen children and adolescents in the COVID-19 group had persistent or new symptoms following SARS-CoV-2 infection; eight reported at least one respiratory symptom, six of whom suffered ongoing breathing problems and two had a persistent cough. Two of these eight patients showed abnormal lung function.
“When we compared the COVID-19 patients with the control group, we found no statistically significant differences in the frequency of abnormal lung function. They occurred in 16% of the COVID-19 group and 28% of the control group,” said study investigator Dr Anne Schlegtendal, a specialist in paediatric and adolescent medicine and paediatric pulmonology.
However, further analysis revealed a reduction in forced vital capacity in patients who had suffered a severe infection by any respiratory pathogen. Severe disease was defined as having breathlessness, a fever above 38.5 degrees Celsius for more than five days, bronchitis, pneumonia or a hospital stay of more than a day.
“These findings should offer some reassurance to children, adolescents and their families,” said Dr Anne Schlegtendal.
“Severity of infection proved to be the only predictor for mild lung function changes and this is independent of a COVID-19 infection. The discrepancy between persistent breathing problems and normal lung function suggests there may be a different underlying cause, such as dysfunctional breathing, which is a problem that has also been identified in adults.”
Commenting on the findings, ERS President Professor Anita Simonds, said: “The findings from these two studies provide important reassurance about the impact of COVID infection on lung function in children and young adults. 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.
“However, further research may shed more light on the effects for people with asthma or who suffer a severe respiratory infection, whether it’s COVID-19 or due to another infective cause. These individuals may be more vulnerable to long-term effects on lung function and underlines the importance for every eligible person to be vaccinated against COVID-19 to reduce overall spread of disease,” said Professor Simonds, who is Honorary Consultant in Respiratory and Sleep Medicine at Royal Brompton Hospital & Professor of Respiratory and Sleep Medicine at NHLI, Imperial College London.