Epidemiology, Microbiology and Severity of Bronchiolitis in the First Post-Lockdown Cold Season in Three Different Geographical Areas in Italy: A Prospective, Observational Study

Abstract

The aim of this study was to understand the epidemiology, disease severity, and microbiology of bronchiolitis in Italy during the 2021–2022 cold season, outside of lockdowns. Before COVID-19, the usual bronchiolitis season in Italy would begin in November and end in April, peaking in February. We performed a prospective observational study in four referral pediatric centers located in different geographical areas in Italy (two in the north, one in the center and one in the south). From 1 July 2021 to 31 January 2022, we collected all new clinical diagnoses of bronchiolitis in children younger than two years of age recording demographic, clinical and microbiological data. A total of 657 children with a clinical diagnosis of bronchiolitis were enrolled; 56% children were admitted and 5.9% required PICU admission. The first cases were detected during the summer, peaking in November 2021 and declining into December 2021 with only a few cases detected in January 2022. RSV was the commonest etiological agent, while SARS-CoV-2 was rarely detected and only since the end of December 2021. Disease severity was similar in children with RSV vs. non-RSV bronchiolitis, and in those with a single infectious agent detected compared with children with co-infections. The 2021–2022 bronchiolitis season in Italy started and peaked earlier than the usual pre-pandemic seasons, but had a shorter duration. Importantly, the current bronchiolitis season was not more severe when data were compared with Italian published data, and SARS-CoV-2 was rarely a cause of bronchiolitis in children younger than 24 months of age.

Resurgence of Respiratory Syncytial Virus Infection During COVID-19 Pandemic Among Children in Shanghai, China

“…In this study, we observed an unusual increase of the RSV detection rate in the summer of 2021 in Shanghai. Interestingly, the abnormal reemergence of RSV during COVID-19 was also observed during the summer months in both northern hemisphere countries including Japan, America, Canada, Israel, Italy ( Public Health Agency of Canada, 2021 ; Ujiie et al, 2021 ; Weinberger Opek et al, 2021 ; Camporesi et al, 2022 ; The US Centers for Disease Control and Prevention, 2022 ), and southern hemisphere countries including Australia and New Zealand ( Agha and Avner, 2021 ; Anglemyer et al, 2021 ; Foley et al, 2021 , 2022 ; Dolores et al, 2022 ; Saravanos et al, 2022 ). Hence, our findings reflected a global phenomenon.…”

“…However, the impacts of the delayed RSV season on patients might vary in different settings. For instance, studies in Italy indicated that the severity of RSV-associated disease was comparable with the previous season according to the respiratory support and PICU admissions (Stera et al, 2021;Camporesi et al, 2022). Also, a study in the United States of America (USA) indicated more severe RSV-related diseases in infants during COVID-19 pandemic (Agha and Avner, 2021).…”

“…However, the unexpected coronavirus disease 2019 (COVID-19) pandemic has exerted extraordinary changes to community behavior at a population level and remarkably restricted the prevalence of respiratory pathogens ( Liu et al, 2021 ; Jia et al, 2022 ). However, along with the normalization of the COVID-19 epidemic control, an atypical reemergence of RSV was reported in various places ( Agha and Avner, 2021 ; Foley et al, 2021 ; Government of Western Australia, 2021 ; Ujiie et al, 2021 ; Camporesi et al, 2022 ; Eden et al, 2022 ; Saravanos et al, 2022 ). Hence, we conducted this research to determine if RSV also resurged in Shanghai in the setting of COVID-19 pandemic and to demonstrate the differences between the resurgence with the previous RSV season.…”

SARS-CoV-2 pandemics and RSV off-season outbreaks

“…The reduction of viral interference, a mechanism by which the replication of respiratory viruses can be inhibited by SARS CoV-2 infection, could also explain the rising numbers (5,10,11).…”

“…Type A clades became dominant and responsible for the outbreaks in widely separated areas of Australia (4). The age distribution was also atypical with a higher-than-average number of RSV infections in older infants (3,5).…”