Coronavirus Bronchiolitis: Insights From the Pre-COVID-19 Era :

In a recently released article in Pediatrics, Mansbach et al reviews several studies examining children hospitalized with bronchiolitis due to four endemic coronaviruses in order to better hypothesize how SARS-CoV-2 bronchiolitis may behave clinically (10.1542/peds.2020-1267). These pre-COVID-19 era studies included children who tested positive for a previously identified coronavirus in isolation or in conjunction with another respiratory virus. Interestingly, the majority of patients (85%) with coronavirus bronchiolitis were co-infected with another pathogen, of which respiratory syncytial virus (RSV) was most commonly identified. Additionally, in all cases of coronavirus bronchiolitis, a higher viral load at symptom onset was associated with increased disease severity.

Given that we still have much to learn about the presentation and pathogenesis of SARS-CoV-2, Mansbach et al’s findings suggest several key points to consider as we evaluate children with COVID-19. First, it may be wise to check a viral load in order to predict which of our bronchiolitic patients with COVID-19 are likely to have a more severe clinical course. Though the relationship between viral load and disease severity is still being established, several studies have already shown a positive correlation in adults.^1,2 Additionally, evidence has emerged that a patient’s viral load may correlate with age. In recent study, children under the age of five with mild to moderate COVID-19 demonstrated greater amounts of the SARS-CoV-2 viral RNA in their nasopharynx than did older children and adults with comparable symptoms.³ As such, a patient’s viral load may evolve as an important clinical tool to assess not only the potential severity of their disease, but also to quantify the potential role they play in the spread of COVID-19 to the general population.

Additionally, given the high false negative rate of most current COVID-19 tests, we may also need to consider the strong possibility of concurrent SARS-CoV-2 infection in any child presenting with bronchiolitis, especially when RSV is detected.^4,5 In other words, the detection of RSV or another respiratory pathogen may not exclude SARS-CoV-2 infection and in fact, may actually alert the clinician to possible co-infection. More research is needed on the topic, but until we better understand the relationship between SARS-CoV-2 and various other respiratory viruses, Mansbach et al suggests that we maintain a high level of clinical suspicion for COVID-19, even in the face of a negative test.

References: 

1. Zheng, Shufa, et al. “Viral Load Dynamics and Disease Severity in Patients Infected with SARS-CoV-2 in Zhejiang Province, China, January-March 2020: Retrospective Cohort Study.” Bmj, 2020, p. m1443., doi:10.1136/bmj.m1443
2. Liu, Yang, et al. “Viral Dynamics in Mild and Severe Cases of COVID-19.” The Lancet Infectious Diseases, vol. 20, no. 6, 2020, pp. 656–657., doi:10.1016/s1473-3099(20)30232-2
3. Heald-Sargent, Taylor, et al. “Age-Related Differences in Nasopharyngeal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Levels in Patients With Mild to Moderate Coronavirus Disease 2019 (COVID-19).” JAMA Pediatrics, 2020, doi:10.1001/jamapediatrics.2020.3651
4. Yang, Yang, et al. “Evaluating the Accuracy of Different Respiratory Specimens in the Laboratory Diagnosis and Monitoring the Viral Shedding of 2019-NCoV Infections.” 2020, Preprint. doi:10.1101/2020.02.11.20021493
5. Zhao, Juanjuan, et al. “Antibody Responses to SARS-CoV-2 in Patients of Novel Coronavirus Disease 2019.” Clinical Infectious Diseases, 2020, doi:10.1093/cid/ciaa344