COVID-19 infection does not appear to affect the lung function of young adults, children or adolescents, according to new research presented at the European Respiratory Society International Congress on 7 September.
The study is the first to investigate the impact of Covid-19 infection of lung function on the age-group . Research was led by Dr Ida Mogensen, MD, post-doctoral fellow at the Karolinska Institute in Stockholm, Sweden.
During her presentation, she told those gathered:
“The COVID-19 pandemic has raised questions about if and how the lung is affected after the clearance of the coronavirus infection, especially in young people from the general population with less severe disease.”
In a press release, she wrote: “Until now, this has not been known.”
The research found that even patients suffering from asthma did not show a statistically significant deterioration in lung function after Covid-19 infection, although there was a trend towards slightly lower measurements for the amount of air they could exhale forcibly in one second – known as forced expiratory air volume in one second (FEV1), which is one of the measures of lung function.
The research was gathered from 661 young people with an average age of 22 years who were part of a large-scale study that enrolled children born between 1994 and 1996 in Stockholm, Sweden, and who have been followed by researchers since the study began.
The most recent pre-pandemic clinical examination was carried out between 2016 and 2019 whilst the examinations at the Covid-19 follow-up took place between October 2020 and May 2021. Collected data studied a range of factors – taking measurements of inflammation, lung function and white blood cells called eosinophils, which are part of the immune system.
Out of the 661 participants who took part, 178 (27%) had antibodies against SARS-CoV-2 indicating that they had previously been infected by the virus.
The researchers measured FEV1, FVC ratio (which represents the volume of air in the lungs that can be exhaled adter taiking the deepest breath possible), and FEV1/FVC ratio, which is an indicator of narrowed airways.
Researchers calculared the changes in lung function between the period before the Covid-19 pandemic, and then during the pandemic. They then compared the percentage change with participants who had not been infected with the virus.
“Our analysis showed similar lung function irrespective of COVID-19 history,” said Dr 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.”
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.
Dr Mogensen also said that the results offered reassurance for young people.
“These results are reassuring for young adults. However, we will continue to analyze 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,” she said.
Second study also “reassuring”
A second study presented at the congress also illustrated that lung function in children and young adults was unimpaired after Covid-19 infection – apart from those who experienced a severe infection.
The second study, presented by Dr Anne Schlegtendal, a specialist in paediatric and adolescent medicine and paediatric pulmonology at University Children’s Hospital, Ruhr-University-Bochum, Germany, focused on the long-term effects of COVID-19 infection between August 2020 and March 21 in 73 children and adolescents aged between five and 18 years.
“There is widely varying evidence on persisting symptoms after COVID-19 in children,” Dr Schlegtendal said during her presentation. She added, “In adults, pulmonary function can show long-term impairment of spirometry values and diffusion capacity.”
Dr Schlegtendal also said:
“Although children and adolescents tend to suffer less severe symptoms from COVID-19 infection than adults, to date there is only preliminary evidence about long-term effects of COVID-19 on pulmonary function in children and adolescents. It’s important to evaluate this given the fact that children worldwide will potentially get infected with SARS-CoV-2 as long as vaccines are predominantly reserved for adults and high-risk groups.”
Dr Schlegtendal and her colleagues carried out lung function tests between 2 weeks and 6 months following Covid-19 infection and compared the results with a control group of 45 children who had not been infected with coronavirus but may have had some other infection.
The participants had different levels of severity of disease. An infection was deemed to be severe if patients suffered from breathlessness, a fever above 38.5 degrees Celsius for more than 5 days, pneumonia, bronchitis, or had to stay in hospital for more than one day.
19 children and adolescents in the Covid-19 group had persistent or new symptoms following SARS-CoV-2 infection, with 8 participants reporting at least one respiratory symptom; 6 participants suffered ongoing breathing problems, whilst 2 reported a persistent cough. 2 out of 8 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.
However, further analysis revealed a reduction in the volume of air in the lungs that can be exhaled after a deep breath – forced vital capacity – in patients who had suffered a severe infection, whether COVID-10 or some other infection,” said Dr Schlegtendal.
“These findings should offer some reassurance to children, adolescents and their families. 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,” she said.
Limitations of the study include the small number of participants; the fact that they were recruited at one hospital alone; that patients reported their symptoms themselves; and a lack of information on long-term outcomes in the control group. Furthermore, the Covid-19 group did not include those suffering sever breathing problems during the acute phase of the infection.
Findings of both studies should offer ‘reassurance’
Anita Simonds, President of the European Respiratory Society and Professor of Respiratory and Sleep Medicine at NHLI, Imperial College London, said that the two studies offer important reassurance for children and young adults in relation to Covid-19 infection.
“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,” she said.
She added that more research is likely needed to determine longer-term side effects of infection.
“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,” Simonds said.