Discussion
This is a descriptive study of patients referred to pediatric pulmonary for Post-Acute Sequelae of SARS-CoV-2 infection (PASC), as defined by the National Institute of Health and Care Excellence guidelines12. Most patients seen for protracted respiratory symptoms following COVID-19 infection were not hospitalized and had mild acute-COVID-19 symptomatology. Protracted respiratory symptoms post-COVID-19 occurred in children as young as 4-years-old. In comparable studies that included adults who did not require hospitalization during initial COVID-19 illness, the most common complaints were dyspnea and fatigue 5,8. In contrast, in our pediatric study population, fatigue was only reported by four patients (13.8%). Similar to our study in which we found that exertional dyspnea was presented in almost all patients, Townsend et al. reported that 62% of adult survivors of COVID-19 reported persistent dyspnea and exertional limitation 75 days after their acute illness. Interestingly, persistent dyspnea and exertional limitation were not associated with initial disease severity in their study16.
In our study, although patients reported persistent exertional dyspnea, cough and exercise intolerance, lung function was normal in most children. Although objective measures of pulmonary function were generally normal, including pulse oximetry, imaging and pulmonary function testing, the six-minute walk test revealed exercise intolerance and significant tachycardia in two-thirds of children tested. This finding suggests that the six-minute walk test may be a low-cost and simple way to evaluate children after COVID-19 and provide a quantitative result that can be trended over time to assess improvement or progression of disability.
We found an increased prevalence of atopy and obesity in our study population that presented with prolonged post-COVID-19 respiratory symptoms. According to the CDC, the most recent national asthma data from 2019 suggests an asthma prevalence of 7% in children under 18 years 17. The asthma prevalence in our study population was 37.9%, which is nearly five times higher than the general population, and two-thirds were atopic. This may suggest that asthma and atopy are risk factors for developing long COVID respiratory symptoms in children and will require larger studies to confirm this association. Obesity, defined as a BMI above the 95thpercentile, may also be linked to persistent symptoms after COVID-19. Our study population has a higher rate of child obesity of 37.9% compared to the local population rate of 20.3% 18; however, this again may reflect study sample bias.
More studies are needed regarding effective management of patients with post-COVID syndrome. Existing guidelines and rehabilitation programs are directed at adult survivors of COVID-19 and recommend multidisciplinary treatment approaches including pulmonary rehabilitation and physical therapy 19. There are limited studies that report improvement in persistent symptoms following vaccination20, but so far there are no studies looking at the impact of vaccination in pediatric patients. Pacing and gradual return to exercise may lessen exertional symptoms 19. Additionally, the high prevalence of asthma and improvement following bronchodilator administration observed in 47.6% of patients suggests that there may be a role for bronchodilators and inhaled corticosteroids in some pediatric patients.
Our population was recruited as a convenience sample and represents a limitation to our study. Patients in this study were seen in a pediatric pulmonary clinic and thus may be more motivated to seek out specialty care or have fewer barriers to accessing care. It is likely that our sample represents a small fraction of total cases of protracted COVID-19 symptoms in children within our catchment area, with the majority of cases being seen by primary care physicians. The youngest subject in our population was four years old, which may reflect the youngest age for subjects to actively report symptoms, thus we cannot comment on whether these protracted symptoms could be observed in even younger patients.
The burden of caring for COVID-19 survivors is expected to be tremendous, and future medical and social interventions must consider the late sequelae of SARS-CoV-2 infection. Even though children experience less severe COVID-19 infections than adults, our study shows that children can have significant long-term respiratory symptoms which can impact quality of life in these children. Our study indicates that ongoing respiratory morbidity can persist even in children with mild acute-COVID-19 infection history and when impairments are not clearly identified by available objective testing. This suggests that there will be an increasing need to follow these children longitudinally to determine the long-term consequences of COVID-19 infection on respiratory health, as this information will have important implications for public health surveillance, health resource allocation, clinical research, and future treatments.