Background RSV detection improves if an additional specimen is collected, but the impact of testing saliva and multiple specimen types has not been assessed. We quantified RSV detection increase with multiple specimen collection over 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% CI86%−141%) using all specimen types compared to NPS alone. Saliva had higher sensitivity than NPS (61.4% versus 47.2%). Among those with congestive heart failure exacerbations, additional specimens increased RSV detection by 267% (95% CI85%−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 is more sensitive than NPS, warranting further study particularly in cardiac patients.

EB, NA, QL, SU, RH, PP, WVK, ME, EG, LJ, and BDG are employees of Pfizer Inc. and may hold stock or stock options. KY is a former employee of Pfizer Inc. and may hold stock or stock options. ARF receives research grants from Pfizer, Moderna, Janssen, AstraZeneca, CyanVac, VaxCo, and BioFire Diagnostics. She is a part of the advisory boards for Sanofi, GSK, Moderna, Pfizer, ADMA Biologics. JR, RC, KK, AJ, and CV have no conflicts of interest to declare.

This work was supported by Pfizer Inc. This study was conducted as a collaboration between multiple sites (Norton and Sinai) and Pfizer. Norton and Sinai sites were the study sponsors.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Western-Copernicus Group (WCG) IRB approval [Central IRB] gave ethics approval for the four hospitals in Louisville, Kentucky (#21-N0325). For the three hospitals in Ontario, Canada; Mount Sinai Research Ethics Board of Mount Sinai Hospital gave ethical approval (# 22-0096-E), North York General Hospital Research Ethics Board of North York General Hospital gave ethical approval (#5522), and Sunnybrook Research Ethics Board of Sunnybrook Health Sciences Centre gave ethics approval (#2023-0197-562).

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