LONDON: COVID-19 infection does not appear to impair the lung function of children and adolescents, according to a study presented at the virtual European Respiratory Society International Congress on Tuesday.
A team led by researchers at the Karolinska Institute, Sweden, found that even patients with asthma did not show a statistically significant deterioration in lung function.
However, such patients showed 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.
A second study presented at the conference on Sunday showed that the lung function in children and adolescents was also unimpaired after COVID-19 infection, apart from those who experienced a severe infection.
"The COVID-19 pandemic has raised questions about if and how the lung is affected after clearance of the coronavirus infection, especially in young people from the general population with less severe disease," said Ida Mogensen, a post-doctoral fellow at the Karolinska Institute.
The first study gathered information from 661 young people with an average age of 22 years who were part of a large research that enrolled children born between 1994 and 1996 in Stockholm, and who have been followed by researchers ever since.
Collected data included measurements of lung function, inflammation and white blood cells called eosinophils, which are part of the immune system. Of the 661 participants, 178 had antibodies against the SARS-CoV-2 virus, indicating they had been infected.
The researchers measured FEV1, forced vital capacity (FVC) which represents the volume of air in the lungs that can be exhaled after a taking the deepest breath possible, and FEV1/FVC ratio, which is an indicator of narrowed airways.
They calculated the changes in lung function between the period before the and during the pandemic. The researchers then compared the percentage change with participants who had not been infected. "Our analysis showed similar lung function irrespective of COVID-19 history," said Mogensen.
When the researchers included 123 participants with asthma in the analysis, the 24 per cent who had had COVID-19 showed 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, they said.
The second study, presented by Anne Schlegtendal, from the University Children's Hospital in Germany, looked at 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.
Schlegtendal and colleagues carried out 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.
The participants had different severity of disease. An infection was considered severe if patients suffered breathlessness, a fever above 38.5 degrees Celsius for more than five days, bronchitis, pneumonia or stayed in hospital for more than a day.
Nineteen children and adolescents in the COVID-19 group had persistent or new symptoms following SARS-CoV-2 infection, the researchers found. 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, they said. "When we compared the COVID-19 patients with the control group, we found no statistically significant differences in the frequency of abnormal lung function," Schlegtendal said.
The researchers acknowledged some limitations in their study, including the small number of participants. The participants were recruited at a single hospital, patients reported their symptoms, and a lack of information on long-term outcomes in the control group, they said.
In addition, the COVID-19 group did not include those with severe breathing problems during the acute phase of the infection. "The findings from these two studies provide important reassurance about the impact of COVID infection on lung function in children and young adults," said Anita Simonds, a professor at Imperial College London, UK, who was not involved in the research.
"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," Simonds added.