On the SARS-CoV-2 “Variolation Hypothesis”: No Association Between Viral Load of Index Cases and COVID-19 Severity of Secondary Cases

• DOI: 10.3389/fmicb.2021.646679
• Publication Date: 2021-03-16T06:29:51Z
• Authors: Mattia Trunfio; Bianca Maria Longo; Francesca Alladio; Francesco Venuti; Francesco Cerutti; Valeria Ghisetti; Stefano Bonora; Giovanni Di Perri; Andrea Calcagno
• Keywords: Index case

Background: Emerging evidence supports the “variolation hypothesis” in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), but derivative idea that viral load of index cases may predict disease severity secondary could be unsubstantiated. We assessed whether prevalence symptomatic infections, hospitalization, and deaths household contacts 2019 novel coronavirus (COVID-19) differed according to SARS-CoV-2 PCR cycle threshold (Ct) from nasal-pharyngeal swab at diagnosis linked cases. Methods: Cross-sectional study on COVID-19 randomly sampled all infections diagnosed March our Microbiology Laboratory (Amedeo di Savoia, Turin). Data were retrospectively collected by phone interviews Piedmont regional platform for emergency. Index classified as high (HVl) low (LVl) two exploratory cut-offs RdRp gene Ct value. Secondary defined confirmed or symptom based likely when not tested presenting compatible clinical picture. Results: One hundred thirty-two whom 87.9% 289 included. The latter male Caucasian 44.3 95.8% cases, with a median age 34 years (19–57). Seventy-four other 28 Considering both, HVl LVl did differ nor COVID-19-related hospitalization death. No difference between asymptomatic, hospitalized hospitalized, deceased survived was found. Negative findings after adjusting differences time onset collection (median 5 days) removing pediatric Conclusions: amount source does outcomes impelling release assays RNA exact quantification, these negative should inform public health strategies how interpret use data.