COVID-19 disrupted RSV seasons, leading to more hospitalizations
Click Here to Manage Email Alerts
Key takeaways:
- The COVID-19 pandemic disrupted the circulation of other respiratory viruses in children, including RSV.
- Younger children were more likely to be hospitalized for RSV in 2021 and 2022.
COVID-19 mitigation measures disrupted the circulation of respiratory syncytial virus, leading to atypical season in 2021 and 2022 that saw higher rates of hospitalization among young children, according to research published in Pediatrics.
RSV can cause serious illness, especially in infants and older adults, and is the leading cause of infant hospitalizations in the United States, according to the CDC. A surge of pediatric RSV stretched hospital capacity in 2022, and the virus was part of a winter tripledemic of respiratory diseases that same year, alongside COVID-19 and influenza.
“Because of this high burden in young children, CDC has supported prospective surveillance through the New Vaccine Surveillance Network for many years to understand the burden of severe RSV disease in children, how it varies from year to year and which children might be at increased risk of severe disease,” Meredith L. McMorrow, MD, MPH, a researcher in the CDC’s Coronavirus and Other Respiratory Viruses Division, told Healio.
“We also know that the COVID-19 pandemic disrupted the circulation of other respiratory viruses in children, so this work was particularly important to understand RSV hospitalization rates in recent years,” McMorrow said.
‘All babies are at risk’
McMorrow and colleagues estimated annual RSV-associated hospitalization rates among children aged younger than 5 years with acute respiratory illness at seven pediatric medical centers in Cincinnati, Houston, Kansas City, Missouri; Nashville, Tennessee; Pittsburgh; Rochester, New York; and Seattle.
“We asked parents or guardians if we could collect a respiratory sample and test it for 10 common respiratory viruses, including RSV,” McMorrow said. “We also asked for permission to collect immunization records and to review medical records for underlying conditions and measures of severe diseases — like the need for supplemental oxygen.”
Based on how many children were eligible and enrolled at each site, the proportion of children who sought care at that hospital, and the proportion of enrolled children who tested positive for RSV, the researchers estimated RSV-associated hospitalization rates by age group and compared those rates during 2021 and 2022 with pre-pandemic seasonal averages.
In the five seasons from 2016 through 2020, there were a total of 4,243 hospitalizations for RSV among young children at the seven hospitals compared with 1,278 and 1,485 alone in the atypical seasons in 2021 and 2022. Children hospitalized in the atypical seasons — especially 2022 — were more likely to have more than one respiratory virus, require supplemental oxygen, or have a hospital stay lasting 5 days or longer.
Although researchers noted no difference in median age or age distribution between the pre-pandemic and 2021 seasons, the median age of children hospitalized with RSV was higher in 2022 (9.6 months vs. 6 months, P < .001), and RSV-associated hospitalization rates were higher in 2021 and 2022 than the pre-pandemic average across age groups. Comparing 2021 with 2022, RSV-associated hospitalization rates were similar among children aged younger than 2 years. However, children aged 24 to 59 months had significantly higher rates of RSV-associated hospitalization in 2022 (rate ratio = 1.68; 95% CI, 1.37-2).
“All babies are at risk of being hospitalized with RSV,” McMorrow said. “These rates suggest that 2% to 3% of all young babies could be hospitalized with RSV and most hospitalized infants were healthy, term babies with no known risk factors.”
Multiple factors at play
Even with the higher rates among older children, the RSV burden was still 10 times higher among the youngest babies than in children aged 2 to 4 years, McMorrow said.
“There was so much talk of potential ‘immune debt’ and lack of exposure in toddlers, but the greatest burden of severe disease was still in the youngest infants aged [up to] 2 months old,” McMorrow said.
Hospitalization rates were likely higher for a combination of reasons, McMorrow said, including that RSV activity was very limited from May 2020 to March 2021, which resulted in a lack of prior exposure among some infants and young children. In 2022, the RSV season aligned with the peak period of co-circulation of rhinoviruses and enteroviruses, which also may have contributed to more hospitalizations among older children.
“Additionally, after months of school and day care closures, masking, and limiting social activities, many Americans were ready to see friends and family and reconnect, perhaps contributing to even more exposures to RSV in young children than usual,” McMorrow said. “Summer and fall are times when there are many family gatherings, sporting events and other social activities that may have resulted in even more exposures to RSV than in a typical winter season.”
Last summer, the FDA approved Pfizer’s maternal RSV vaccine to protect infants during their first 6 months after birth. It also approved nirsevimab, a monoclonal antibody to prevent RSV in infants entering their first RSV season.
“We are currently working on estimating the effectiveness of new RSV prevention products on RSV-associated hospitalization, and hope that with widespread use, fewer and fewer babies with be hospitalized with RSV,” McMorrow said.
Collapse
Read more about
Click Here to Manage Email Alerts