# P-675. Chronic Conditions as Risk Factors for Respiratory Syncytial Virus-Associated Hospitalization among Community-Dwelling Adults Aged 18-49 Years, 2016-2017 and 2017-2018 Seasons

## TL;DR

This study found that chronic conditions like diabetes and kidney disease increase the risk of RSV hospitalization in adults aged 18-49.

## Contribution

The study identifies specific chronic conditions that elevate RSV hospitalization risk in younger adults, informing potential vaccination strategies.

## Key findings

- Chronic kidney disease had the highest adjusted rate ratio of 13.9 for RSV hospitalization.
- Adults with ≥2 chronic conditions had an 8.3-fold higher RSV hospitalization rate than those with none.
- Non-severe obesity was associated with a 1.6-fold higher RSV hospitalization rate.

## Abstract

Data on chronic conditions associated with increased respiratory syncytial virus (RSV)-associated hospitalization rates among adults aged ≥ 50 years have guided RSV vaccination recommendations. Similar data are needed for younger adults.

We compared RSV hospitalization rates among community-dwelling adults aged 18-49 years with and without nine chronic medical conditions in a 38-county catchment area across seven states. Numerators included adults with and without each chronic condition who were hospitalized with laboratory-confirmed RSV infection identified through the RSV Hospitalization Surveillance Network (RSV-NET) during two RSV surveillance seasons during 2016-2018. Denominators were catchment area population estimates of adults with and without self-reported history of each chronic condition from the Behavioral Risk Factor Surveillance System and the US Census. Poisson regression using Monte Carlo simulation generated unadjusted rates and adjusted rate ratios (aRR) and 95% Monte Carlo uncertainty intervals (UI), adjusted for sex and race or ethnicity group.

Among community-dwelling adults aged 18-49 years, RSV hospitalization rates ranged from 11.7 hospitalizations per 100,000 (UI: 5.9, 23.6) for adults with non-severe obesity (body mass index [BMI] 30-39 kg/m2) to 113.1 hospitalizations per 100,000 (UI: 47.3, 274.3) for adults with chronic kidney disease (Figure 1). Those with each of the nine chronic conditions had higher RSV hospitalization rates compared to those without the respective conditions: chronic kidney disease (aRR=13.9, UI: 9.2, 21.2), diabetes (aRR=6.1, UI: 4.1, 9.1), severe obesity (BMI ≥ 40 kg/m2; aRR=5.3, UI: 3.4, 8.3), chronic obstructive pulmonary disease (aRR=4.0, UI: 2.4, 6.5), asthma (aRR=3.9, UI: 3.0, 5.1), coronary artery disease (aRR=3.6, UI: 2.1, 6.0), stroke (aRR=3.6, CI: 2.3, 5.9), current smoking (aRR=2.1, UI: 1.6, 2.7), and non-severe obesity (aRR=1.6, UI: 1.1, 2.4) (Figure 2). RSV hospitalization rates were higher among adults aged 18-49 years with 1 (aRR=2.2, UI: 1.7, 2.9) or ≥2 chronic conditions (aRR=8.3, UI: 6.4-10.9) vs. none.

Chronic conditions were associated with higher rates of RSV hospitalization among younger adults, which can guide national vaccination recommendations.

Lucy S. Witt, MD, MPH, Merck & Co: Grant/Research Support William Schaffner, MD, Abbott Dignostics: Honoraria