Post-lockdown respiratory virus epidemiology: a monocentric observational study

ABSTRACT
During the 2020 lockdown and post-lockdown, we assisted in almost zeroing respiratory infections. This study aimed to describe the first epidemic of respiratory viruses after the easing of nonpharmaceutical interventions (NPIs) for the containment of COVID-19 in a pediatric cohort of patients.
All children consecutively hospitalized because of a respiratory infection at our department of Clinical and Experimental Medicine, Pediatric Respiratory and Cystic Fibrosis Unit – San Marco University Hospital in Catania, Italy, from October 1^st, 2021, to March 15^th, 2022 were tested for respiratory viruses. Among these patients, in the subgroup of children with bronchiolitis, we investigated the following endpoints: the etiology, the mean duration of hospitalization (mean ± SD), the severity of the disease (Clinical Respiratory Score), and the respiratory support provided (HFNC or Helmet-CPAP). For statistical analysis, SPSS 28.0.1.1 (14) software was used. A 2-tailed t-test for unpaired data was applied to compare the mean duration of hospitalization and need for ventilation, and a chi-square test was applied to relate the severity of viruses.
A total of 138 children were included in the study. The infection of the Respiratory Syncytial Virus (RSV) was the most frequently observed (23.2%), followed by Bocavirus (10.87%), Rhinovirus (hRV) (4.38%), Parainfluenza virus (2.9%), Enterovirus (2.17%), endemic Coronavirus (1.45%) and Metapneumovirus (1.45%). 53.6% of patients resulted negative. Of the 138 children, 62 (45%) had a diagnosis of bronchiolitis: in 40% of these children, we isolated RSV, in 8% Bocavirus, in 3.23% Rhinovirus, in 3.3% Parainfluenza virus, 1.61% endemic Coronavirus and Metapneumovirus. In the remaining 42% of patients with bronchiolitis, no viruses were isolated by nasal swabs. The mean duration of hospitalization for RSV-related bronchiolitis (mean 9.48 days ± SD 3.95) was significantly higher (p < 0.05) compared to the non-RSV-related bronchiolitis (mean 7.22 days ± SD 3.7). According to the clinical respiratory score, RSV-related bronchiolitis resulted in more severe (p < 0.05) than non-RSV ones, and consequently, it has been associated with a higher risk (p < 0.05) of being subject to ventilation either with helmet CPAP or HFNC.
During the considered period, RSV was the most widespread respiratory virus, in fact it has been isolated through nasal swab in the 23.2% of the whole study group of 138 patients). RSV was responsible for the most severe bronchiolitis cases, associated with a higher hospitalization length and a more severe disease compared to non-RSV-related bronchiolitis.

ABBREVIATIONS
RSV: respiratory syncytial virus; NPIs: nonpharmaceutical interventions; CRS: clinical respiratory score; HFNC: High Flow Nasal Cannula.

Received: Sept 5, 2022
Accepted: Oct 10, 2022
Published: Nov 1, 2022