Adults Follow Biannual Pattern of RSV Infection

Timely associations between biannual waves of respiratory syncytial virus (RSV) were found in adults and children who experienced RSV seasons pre- and post the COVID-19 pandemic, according to a study published in the Journal of Clinical Virology.

The main pathogen causing respiratory infections in infants and young children is RSV, which is a major cause of mortality in the age group. RSV is also known to lead to illness and mortality in older adults. This study focused on 7 RSV seasons from 2016 to the present in both children and adults to report on the differences, similarities, and associations of infections in the 2 age groups.

The study was performed at the University Children’s Hospital and the Hospital of the Order of St. John, both in Regensburg, Germany. Patient records were used to collect information on age, sex, and parameters that determined the severity of the infection of RSV. Comorbidities were also evaluated.

The start and end of a season of RSV was determined retrospectively; it was determined that the end of the season would be when 97% of all cases of that season had been hospitalized. The seasons were determined separately for children and adults. All participants had nasal or nasopharyngeal swabs or oropharyngeal gargle-solution tests done to determine their diagnosis of RSV, influenza A or B, or COVID-19.

A total of 1903 patients who were hospitalized for RSV from 2016/2017 to 2022/2023 were included in this study, 1446 of whom were children with a median age of 8 months. The median age of the adult patients was 77 years. Older adults were inpatients for significantly longer compared with children (median, 8 vs 4 days, respectively). Older adults were also admitted to the intensive care unit (ICU) more frequently than children.

A seasonal pattern of RSV infections and hospitalizations was found in children and young adults, starting in late fall to early December with a peak in January and February and alternating between years. A season that had high prevalence was followed by a season of low prevalence. This was observed in older adults as well as children.

The RSV season was completely absent in 2020/2021 in both children and adults. This was followed by a start of the RSV season in 2021 that was earlier for children, starting in August 2021, and had a sharp increase in infections and hospitalizations. However, the season did abide by the alternating pattern of low-prevalence season, as cases and hospitalizations were not significantly more than in the 2 previous low prevalence seasons. The 2022/2023 season was expected to be high prevalence and it was, starting slightly earlier than normal but not as early as the previous season. There was no significant difference in ICU admission rate or duration of hospital treatment in between seasons in children and infants.

The researchers found that there were significant differences in the RSV season of 2021/2022 for older adults. There was a significantly lower number of patients in this season compared with the prepandemic seasons (15 in 2021/2022 compared with 97, 49, 112, and 45 in the prepandemic seasons). The RSV season was delayed by 51 days in adults compared with children in other seasons.

One limitation of this study was that it had a monocentric design, which may underestimate the total number of adults that were hospitalized with RSV.

The researchers concluded that the waves of RSV in adults followed a biannual pattern similar to those seen in children. Timely associations between these waves exist both pre- and post pandemic.

Reference

Kiefer A, Pemmerl S, Kabesch M, Ambrosch A. Comparative analysis of RSV-related hospitalisations in children and adults over a 7 year-period before, during and after the COVID-19 pandemic. J Clin Virol. Published online July 6, 2023. doi:10.1016/j.jcv.2023.105530