Prevalence of SARS-CoV-2 and Influenza Coinfection and Clinical Characteristics Among Children and Adolescents Aged <18 Years Who Were Hospitalized or Died with Influenza — United States, 2021–22 Influenza Season

Abstract

The 2022-23 influenza season shows an early rise in pediatric influenza-associated hospitalizations (1). SARS-CoV-2 viruses also continue to circulate (2). The current influenza season is the first with substantial co-circulation of influenza viruses and SARS-CoV-2 (3). Although both seasonal influenza viruses and SARS-CoV-2 can contribute to substantial pediatric morbidity (3-5), whether coinfection increases disease severity compared with that associated with infection with one virus alone is unknown. This report describes characteristics and prevalence of laboratory-confirmed influenza virus and SARS-CoV-2 coinfections among patients aged <18 years who had been hospitalized or died with influenza as reported to three CDC surveillance platforms during the 2021-22 influenza season. Data from two Respiratory Virus Hospitalizations Surveillance Network (RESP-NET) platforms (October 1, 2021-April 30, 2022), § and notifiable pediatric deaths associated ¶ with influenza virus and SARS-CoV-2 coinfection (October 3, 2021-October 1, 2022)** were analyzed. SARS-CoV-2 coinfections occurred in 6% (32 of 575) of pediatric influenza-associated hospitalizations and in 16% (seven of 44) of pediatric influenza-associated deaths. Compared with patients without coinfection, a higher proportion of those hospitalized with coinfection received invasive mechanical ventilation (4% versus 13%; p = 0.03) and bilevel positive airway pressure or continuous positive airway pressure (BiPAP/ CPAP) (6% versus 16%; p = 0.05). Among seven coinfected patients who died, none had completed influenza vaccination, and only one received influenza antivirals. † † To help prevent severe outcomes, clinicians should follow recommended respiratory virus testing algorithms to guide treatment decisions * These authors contributed equally to this report.† These senior authors contributed equally to this report. § Data from FluSurv-NET beyond April 30, 2022, did not include variables required to determine influenza and SARS-CoV-2 coinfection status. ¶ https://www.cdc.gov/flu/weekly/overview.htm#PediatricMortality ** The 2021-22 influenza season was defined as MMWR week 40 of 2021 through MMWR week 39 of 2022 (October 3, 2021-October 1, 2022). https://ndc.services.cdc.gov/wp-content/uploads/MMWR_Week_overview.pdf † † Receipt of COVID-19 treatment was not collected on patients in this report.

Surveillance of seasonal influenza viruses during the COVID‐19 pandemic in Tokyo, Japan, 2018–2023, a single‐center study

“…This report, as the sole cross‐sectional influenza surveillance conducted in Tokyo, has revealed a distinct period of influenza absence, followed by its resurgence. The study provides evidence that the decrease in the number of influenza tests did not necessarily lead to a decrease in the number of positive cases 9 and supports the notion that simultaneous infection with influenza and SARS‐CoV‐2 is rare 24,26 …”

“…The study provides evidence that the decrease in the number of influenza tests did not necessarily lead to a decrease in the number of positive cases 9 and supports the notion that simultaneous infection with influenza and SARS-CoV-2 is rare. 24,26 Additionally, this investigation presents initial evidence confirming a reduction in influenza cases among the elderly during the COVID-19 pandemic, as alluded to numerically in the database of the Tokyo Metropolitan Government. 13 We have concerns that a resurgence of influenza might occur after the relaxation of infection control measures such as universal mask wearing and the restoration of active international travel.…”

Cocirculation and coinfection of multiple respiratory viruses during autumn and winter seasons of 2023 in Beijing, China: A retrospective study

“…(32/575) of hospitalized pediatric influenza patients had SARS-CoV-2 coinfection, during the 2021-2022 influenza season. 37 In addition, the study identified increased use of mechanical ventilation among coinfected patients, indicating potentially more severe disease among coinfected patients. 37 Consistently, our study reports patients with coinfections suffered more severe symptoms than those with monoinfection.…”

Current status and reflections on the diagnosis and treatment of respiratory tract infections in children in the COVID‐19 pandemic and post‐COVID‐19 era

“…Coinfection significantly increases the risk of severe outcomes such as respiratory distress, the need for invasive mechanical ventilation, and death. [66][67][68] Therefore, in the post-pandemic era, it is crucial to address how SARS-CoV-2 and seasonal respiratory virus coinfections impact the severity of childhood RTIs. Nowadays, as SARS-CoV-2 has become less virulent, COVID-19 may gradually evolve into a seasonal and regional epidemic requiring regular vaccinations.…”

“…In particular, IFV, HRSV, and HADV are the most commonly observed coinfecting viruses. Coinfection significantly increases the risk of severe outcomes such as respiratory distress, the need for invasive mechanical ventilation, and death 66–68 . Therefore, in the post‐pandemic era, it is crucial to address how SARS‐CoV‐2 and seasonal respiratory virus coinfections impact the severity of childhood RTIs.…”