Detection of RSV using nasopharyngeal swabs alone underestimates RSV-related hospitalization incidence in adults: the Multispecimen study’s Final Analysis

Abstract

Background Most epidemiologic studies and clinical testing use a single nasal/nasopharyngeal swab for RSV detection. Previous studies have documented that RSV detection improves if a single additional specimen is added to nasal/nasopharyngeal swab, but the impact of using multiple specimen types has not been assessed. We quantified RSV the increase in RSV detection using multiple specimen testing compared to nasopharyngeal swab (NPS) alone. Methods Prospectively enrolled hospitalized adults aged ≥40 years with acute respiratory illness in seven hospitals in US and Canada had NPS, saliva, sputa, and acute/convalescent sera collected and tested. Results Among 3,669 enrolled participants, 100% had NPS, 97.7% saliva, 33.0% sputum, and 33.4% paired serology. RSV detection was 112% higher (95%CI: 86%–141%) using all specimen types compared to NPS alone. Serology test sensitivity was the highest (73.0%; 95%CI: 65.1–80.8), followed by sputum (70.1%; 95%CI: 62.1–78.0), saliva (61.4%; 95%CI: 55.4–67.5), and NPS (47.2%; 95%CI: 41.1–53.4). Among those with congestive heart failure exacerbations, additional specimens increased RSV detection by 267% (95%CI: 85%–625%) and saliva detected more infections than NPS. Among 1013 subjects with paired NPS from different timepoints tested on the same platform, specimens collected on average 1 day later detected 30% less RSV infections. Conclusions RSV detection increased over 100% using four specimen types versus NPS alone, suggesting a 2-fold correction factor is appropriate for incidence/prevalence studies relying on NPS alone. Saliva was more sensitive than NPS, warranting further study particularly in cardiac patients.