The COVID-19 endemic: calm before the storm of paediatric viral respiratory illnesses

In late October 2022, emergency rooms across Canada and the USA began to experience an influx of paediatric patients presenting with severe respiratory illnesses associated with influenza and respiratory syncytial virus (RSV) infections. This sudden wave of respiratory illnesses came on the heels of expert predictions that the coronavirus disease 2019 (COVID-19) pandemic was transitioning towards an endemic state as a result of hybrid immunity from widespread infections and vaccinations.1 In Ontario, Canada, the number of paediatric emergency room visits peaked in early November 2022 with over 2000 daily visits from paediatric patients presenting with respiratory illnesses. In comparison, only around 1000 daily visits for respiratory complaints were recorded in November 2021, and around 800 daily visits were recorded during similar time periods in the years before the COVID-19 pandemic.2 Despite ample warnings from previous RSV surges in Australia and the USA during the pandemic,3 many provincial healthcare systems across Canada were ill-equipped to handle the increasing cases of severe paediatric respiratory illnesses. According to the Ontario Ministry of Health, the number of paediatric ICU (PICU) hospitalizations peaked on 10 November 2022, with 122 paediatric patients requiring PICU admission. However, there were only 112 PICU beds available in the province.4 As a result, many hospitals were forced to cancel elective paediatric surgeries and limit access to speciality clinics. This issue is exacerbated by a nationwide shortage of over-the-counter medications for treating symptoms of viral infections, including paediatric acetaminophen and ibuprofen. In the face of the ongoing state of crisis, this commentary aims to provide a brief review of potential causes as well as management and preventive strategies against the recent increase in paediatric viral respiratory illnesses in Canada. During the peak of the COVID-19 pandemic, a variety of infection control measures—including masking, increased sanitation and social distancing—were used in efforts to reduce the transmission of SARS-CoV-2. While these measures were effective, they also led to an unintended consequence of reducing RSV and influenza cases around the world. In Canada, 339 627 RSV tests were reported through the Centre for Immunization and Respiratory Infectious Diseases from August 2020 to May 2021, of which only 239 tests were positive for RSV. In contrast, 18 860 tests were positive out of 412 861 RSV tests reported from August 2019 to May 2020.3 It has been hypothesized that the reduction in viral respiratory illnesses resulted in an ‘immunity gap’ among infants and young children who avoided common respiratory infections during the pandemic and thus lacked the pathogen-specific protection against future infections.5 A reduction in maternal exposure to common respiratory viruses may have also led to the reduced transference of transplacental antibodies in infants, thus leaving young infants more vulnerable to viral infections.6 Lastly, many vaccination and disease prevention programs were suspended during the pandemic to conserve healthcare resources and avoid unnecessary hospital visits. Most notably, several Canadian programs which provided prophylaxis against RSV infections using monoclonal antibodies in high-risk infants were paused or shortened due to the reduced RSV incidence and public health guidelines.3 These combined factors likely contributed to the increased susceptibility to severe viral illnesses among the paediatric population. As a result, both Australia and the USA observed out-of-season RSV outbreaks in 2021,3,7 with some US hospitals reporting increased severity of RSV illnesses in addition to the increased incidence.8 For young children, RSV is associated with substantially higher rates of emergency room visits and hospitalization compared to influenza.9 Severe RSV infections tend to manifest clinically as bronchiolitis, which is the obstruction of lower respiratory tracts by acute inflammation, oedema, mucus and necrotic epithelial cells. The disease course typically starts as a 2–3 days viral prodrome of fever, cough and rhinorrhoea, progressing to tachypnoea, wheezing, crackles and a variable degree of respiratory distress.10 Other respiratory viruses, such as influenza, can also cause similar symptoms. Bronchiolitis is diagnosed using physical exams and history, and additional investigations are not recommended unless the patients present with severe disease.10,11 Risk factors for developing severe RSV infections requiring hospitalization include young age (<6 months), prematurity (<36 weeks gestation), comorbid cardiac or lung diseases, immunodeficiencies, Down syndrome and living in remote or isolated communities.12 Illnesses associated with influenza and RSV infections tend to be self-limiting, thus management of the disease largely consists of supportive treatments. Supplemental oxygen should be administered to maintain saturation >90%, fluid supplementation should be given as needed (ideally though the nasogastric route due to ease of insertion and allowance for enteral nutrition), and superficial nasal suctioning should be given if secretions impair breathing or feeding. Bronchodilators, antibiotics, epinephrine, hypertonic saline, corticosteroids, chest physiotherapy and aerosol therapies are not recommended.10,11 Ribavirin is the only antiviral approved for the treatment of RSV infections in Canada and the USA in high-risk infants; however, it is administered on a case-by-case basis in severe patients due to questionable efficacy, expense, and difficult route of administration.10 The influx of patients in Canadian paediatric emergency rooms and PICUs is reminiscent of the initial waves of COVID-19 when limited healthcare resources were stretched to their limits. The solution to the current dilemma, in the absence of adequate PICU capacity and healthcare staffing, is the same as our approach towards SARS-CoV-2—to curb viral transmission. Influenza vaccines, which are available for children aged >6 months in Canada (and are recommended by the Canadian Paediatric Society for the 2022/2023 flu season), should be readily administered.13 However, there is no vaccine available for the prevention of RSV infections. While a monoclonal antibody product, palivizumab, is available for prophylaxis against RSV in specific high-risk paediatric patients, it is not indicated for routine protection against RSV in the general population.12 In addition to vaccinations, hygienic practices such as hand washing/disinfection and surface sanitation are accessible and effective methods to prevent direct and indirect viral transmissions and should be practised by the public.14,15 And as shown repeatedly during the pandemic, masking is a proven approach to reducing the spread of respiratory viral illnesses. A recent systematic review of randomized trials found that masking can reduce the risk of acquiring respiratory viral infections by 34%, with observational studies yielding an even greater risk reduction of up to 69%.16 Thus, the implementation of mandatory in-door masking policies—beyond the current ‘strong recommendations’ from provincial governments in Canada—should be considered to help our healthcare systems weather the storm of paediatric respiratory illnesses. No data is disclosed in this manuscript. Funding: No funding received. Conflict of interest: None declared. Jiawen Deng (Investigation [lead], Supervision [lead], Writing—original draft [lead], Writing—review & editing [lead]), Kiyan Heybati (Investigation [supporting], Writing—original draft [supporting], Writing—review & editing [supporting]), Cristian Garcia (Investigation [supporting], Writing—original draft [supporting], Writing—review & editing [supporting]), Emma Huang (Investigation [supporting], Writing—original draft [supporting], Writing—review & editing [supporting]) and Fangwen Zhou (Investigation [supporting], Writing—original draft [supporting], Writing—review & editing [supporting]).

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