Comparison of Viral Loads in Patients with Co-infections vs. Single-virus Infections

Abstract

Background Molecular testing for respiratory viruses in clinical practice is common, often with multiple viruses detected. Viral load has been correlated with illness severity, but correlation of co-detection of viruses and viral load is less clear. We sought to compare cycle threshold (Ct) values, a marker inversely related to viral load, between single vs. co-detection of common respiratory viruses. Methods Children <18 years with respiratory symptoms and/or fever who presented to the ED or were admitted were enrolled. Nasal/throat specimens were obtained and combined. Singleplex qRT-PCR was used to test for 11 respiratory viruses. Clinical and demographic information were collected. Results From 11/15/15-7/15/16, 1255 children were enrolled, with median age of 26.5 months, 53.4% male, 54.3% White, 38.7% Black, 6.4% other, and 23.5% Hispanic. The median days of illness were 3 days. Of the total cohort, 904 (72%) tested positive for at least one viral pathogen. Table 1compares Ct values of single vs. co-detection for each individual virus. Conclusion Single detection with RSV, HRV, AdV, and PIV had lower Ct values, indicating higher viral loads, compared with co-detection with other viruses. Additional research is needed to understand the reason for lower viral loads for co-detection vs. single detection in select respiratory viruses. Disclosures W. Schaffner, Pfizer: Scientific Advisor, Consulting fee. Merck: Scientific Advisor, Consulting fee. Novavax: Consultant, Consulting fee. Dynavax: Consultant, Consulting fee. Sanofi-pasteur: Consultant, Consulting fee. GSK: Consultant, Consulting fee. Seqirus: Consultant, Consulting fee. N. B. Halasa, sanofi pasteur: Research Contractor, Research support. Astra Zeneca: Research Contractor, Grant recipient.

Epidemiology and molecular characteristics of respiratory syncytial virus (RSV) among italian community-dwelling adults, 2021/22 season

“…We then observed that compared with RSV mono-detections, samples tested positive for both RSV and another respiratory pathogen (especially if viral) showed significantly lower viral loads. These findings are in line with a pediatric study conducted during the 2015/16 season: Ct values in RSV single detections were on median 1.5 points lower (25.5 vs. 27.0; p = 0.05) than in RSV co-detections [45]. This observation may be explained by a negative viral inference that has been described for RSV co-infections with influenza A virus, rhinovirus and metapneumovirus [46].…”

Epidemiology and molecular characteristics of respiratory syncytial virus (RSV) among Italian community-dwelling adults, 2021/22 season

“…Moreover, compared with RSV mono-infections, samples tested positive for both RSV and another respiratory pathogen showed signi cantly lower viral loads. These ndings are in line with a pediatric study conducted during the 2015/16 season: Ct values in RSV single infections were on median 1.5 points lower (25.5 vs 27.0; p = 0.05) than in RSV co-detections [39]. This observation may be explained by a negative viral inference that has been described for RSV co-infections with in uenza A virus, rhinovirus and metapneumovirus [40].…”