Study Results Show Estimated 2022 RSV Rates Could Be Twice as High as Previous 2 Years

The state-level respiratory syncytial virus (RSV) hospitalization rates for 2022 could be at least twice as high as those observed in the previous 2 years and the highest within the past 17 years, according to the results of a study published in Frontiers in Pediatrics.

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Investigators used a dataset of hospital discharge records from the Texas Public Use Data Files (PUDF), which were arranged each year by quarter. They used data on discharge diagnoses, length of stay, patient age, patient county, and patient status at the end of service.

The cases included RSV, acute bronchiolitis caused by RSV, and pneumonia caused by RSV. All individuals included in the study were younger than aged 5 years.

Investigators also evaluated the RSV-associated hospitalization rates in this study compared with those reported in the RSV Hospitalization Surveillance Network (RSV-NET) from the CDC between 2018 and 2022.

There were 158,920 RSV-associated hospitalizations identified between 2006 and 2021. Investigators found that most RSV-hospitalizations between 2006 and 2019 were for children younger than aged 5 years, but the proportion was lower in 2020 and 2021.

In the PUDF, children younger than aged 5 years were separated into 3 categories: aged 1 to 28 days; 29 to 365 days; and 1 to 4 years. Investigators found that the highest percentage of hospital admissions between 2006 and 2019 was observed in the 29 to 365 days group at 65%, and the lowest was the 1 to 28 days group at 8%.

These data were consistent across quarters, they said.

In 2020, the distribution of patient age at admission was similar. However, in 2021, the highest percentage was seen for those who were 1 to 28 days at approximately 57%, followed by 1 to 4 years at approximately 40%.

Additionally, seasonal patterns of hospital admissions for individuals aged 4 years and younger were consistent between 2006 and 2019, with the seasonal peaks observed between October and December and January and March.

The highest number of cases was observed in the 2010, 2011, and 2019 flu seasons. There was a low number of hospitalizations observed in the 2020 season, followed by an intensified peak in 2021 between July and September hospitalizations.

The outbreak peak that investigators estimated for the 2020 July to December season, was observed in 2021 between April and September. The expected peak in 2020 between October and December and in 2021 between July and September was 1.5 times higher than expected.

The similar outcomes were seen between April and June was 2.6 times higher than those predicted in a typical season and 5 times higher than if a seasonal shift occurred.

However, in 2021 between October and December, there was a lower-than-expected number of cases by 1.5 times in a delayed season or 1.7 times lower in a typical season.

Investigators compared these rates to those reported in the RSV-NET from the CDC, which they expected to have difference values, because of the methodologies to obtain data.

The RSV-NET used data from acute-care hospitals in 58 counties across 12 states and laboratory-confirmed RSV-associated hospitalizations divided by the total population in the surveillance area to calculate the rates.

Investigators found that the magnitude of RSV-associated hospitalization rates in 2018 and 2019 season prior to COVID-19 were comparable to, but not the same, as data from the RSV-NET. The seasonal peak for the RSV-NET were observed in January to March.

They found that from 2018 to 2021, the state and mean county level hospitalization rates were 1.9 and 9.5 times higher than those reported in RSV-NET, respectively.

From 2020 to 2021, the onset of outbreak had a mean county level rate 43 times high than the RSV-NET levels, and the state hospitalization rate was 5 times higher than RSV-NET.

Reference

Uwak I, Johnson N, Mustapha T, Rahman M, et al. Quantifying changes in respiratory syncytial virus-associated hospitalizations among children in Texas during COVID-19 pandemic using records from 2006 to 2021. Front Pediatr. 2023;11:1124316. doi:10.3389/fped.2023.1124316