Viral load dynamics and shedding kinetics of mpox infection: a systematic review and meta-analysis

Viral load dynamics and shedding kinetics are critical factors for studying infectious diseases. However, evidence on the viral dynamics of mpox remains limited and inconclusive. Thus, we aimed to provide a comprehensive understanding of the viral load and viability of the re-emerged mpox virus since 2022.

For this systematic review and meta-analysis, we searched PubMed/MEDLINE, Embase and Google Scholar for published articles that are related to mpox viral dynamics up to April 2023.

From 19 studies, 880 samples and 1477 specimens were collected. The pooled median Ct values appeared in the following order: skin lesion [Ct value 21.7 (IQR 17.8-25.5)], anorectal [22.3 (16.9-27.6)], saliva [25.9 (22.5-31.1)], oral [29.0 (24.5-32.8)], semen [29.6 (25.9-33.4)], urine [30.5 (24.6-36.4)], pharyngeal [31.9 (26.5-37.3)], urethra [33.0 (28.0-35.0)] and blood [33.2 (30.4-36.1)]. People living with human immunodeficiency virus (HIV) have a lower Ct value in the skin [skin HIV+, 19.2 (18.3-20.0) vs skin HIV-, 25.4 (21.2-29.0)]. From the Ct values and test day since symptom onset, we identified temporal trends of viral load for each specimen type. Changes in the trend were observed at 4 days in saliva, 5 days in blood, 6 days in skin, 7 days in anorectal, urine, semen and pharyngeal and 8 days in the urethra. We determined optimal Ct cutoff values for anorectal (34.0), saliva (27.7) and urethra (33.0) specimens, where a Ct value above each cutoff suggests minimal viral viability. Using these cutoff values, we derived the duration of viable viral isolation in each specific specimen type (anorectal 19 days, saliva 14 days and urethra 14 days).

Skin lesion, anorectal and saliva samples contained the highest viral load. The peak viral load manifests within 4-8 days after symptom onset, and viable virus detection was presumed to cease within 14-19 days from symptom onset in anorectal, saliva and urethral samples.