Study population
Eighteen infants were referred to perform iPFT at our institution due to persistent respiratory complaints with a documented SARS-CoV-2 infection. After exclusion of two infants (one infant due to Down’s syndrome and a congenital heart defect, and the other due to extreme prematurity) sixteen infants were included as cases in the study (81% male), see figure 1 for patient selection and table 1 for additional patient characteristics.
The most common respiratory complaints for which these 16 infants were referred for further evaluation with iPFT were chronic or recurrent cough (56%), recurrent wheezing (19%), and noisy breathing and tachypnea (13% each). Of these sixteen infants, twelve (75%) experienced a symptomatic acute COVID-19 illness, most commonly fever (6/12 (50%)), cough (5/12 (42%)) and dyspnea (4/12 (33%)). In 11 infants, the symptoms were mild. One late-preterm infant suffered a severe neonatal COVID-19 disease with acute respiratory distress syndrome (ARDS), following vertical transmission. Four infants experienced an asymptomatic SARS-CoV-2 infection and were diagnosed following an exposure to a symptomatic individual. The median age at the time of the documented SARS-CoV-2 infection was 4.0 months, interquartile range (IQR)=1.1-7.3 months.
The median age of cases at the time of the iPFT was 10.5 months (IQR = 7.0-13.5), with a median time of 5.5 months (IQR=2.8-8.0) between the documentation of a SARS-CoV-2 infection and the respiratory evaluation with iPFT.
Four hundred and seventy-five subjects were included as controls in the study (65% male, median age at the time of iPFT = 9.4 months, IQR=7.0-13.1) (see figure 1 for patient selection). No statistically significant differences were found between cases and controls in baseline clinical characteristics and the reason for referral to perform iPFT (table 1).