Correlations and Timeliness of Respiratory Syncytial Virus Surveillance Indicators-United States, 2018-2024.

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of hospitalizations in young children and older adults in the United States. Monitoring seasonal RSV activity through national surveillance systems and understanding the relationships among RSV surveillance indicators can help ensure timely administration of prevention products and improve preparedness among healthcare systems and public health programs.

METHODS

We analyzed RSV data across six surveillance years from the National Respiratory and Enteric Virus Surveillance System (NREVSS), National Syndromic Surveillance Program (NSSP), commercial laboratories, New Vaccine Surveillance Network (NVSN), and Respiratory Syncytial Virus Hospitalization Surveillance Network (RSV-NET). We characterized RSV seasonality and compared pediatric and all-age surveillance indicators (percent positivity, percentage of ED visits, and hospitalization rates) at key points during the RSV season. We then estimated cross-correlations and lags between each system and NREVSS before, during, and after the COVID-19 pandemic.

RESULTS

Five RSV seasons occurred between 2018 and 2024. Pediatric indicators were greater than all-age indicators at NREVSS season onset (range: 1.4-6.3 times greater), peak (1.3-5.8), and offset (1.1-4.7). Nationally, indicators were highly correlated across systems (ρ > 0.92) during the prepandemic and postdisruption periods, with minimal lags (0-1 weeks). However, correlations (ρ = 0.48-0.99) and lags (0-6 weeks) varied across regions and time windows during these periods.

CONCLUSIONS

Pediatric surveillance indicators provide the earliest indications of RSV season onset. CDC systems that provide complementary data on RSV activity and associated outcomes are highly correlated at the national and regional levels but may not capture local trends that are important for optimizing prevention.