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Updated: Dec 24, 2025

Vaccinia Virus Infection & Temporal Analysis of Virus Gene Expression: Part 2
Published on: April 10, 2009
Temporal dynamics in viral shedding and transmissibility of COVID-19
Xi He1, Eric H Y Lau2, Peng Wu3
1Guangzhou Eighth People's Hospital, Guangzhou Medical University, Guangzhou, China.
Abstract:
We report temporal patterns of viral shedding in 94 patients with laboratory-confirmed COVID-19 and modeled COVID-19 infectiousness profiles from a separate sample of 77 infector-infectee transmission pairs. We observed the highest viral load in throat swabs at the time of symptom onset, and inferred that infectiousness peaked on or before symptom onset. We estimated that 44% (95% confidence interval, 25-69%) of secondary cases were infected during the index cases' presymptomatic stage, in settings with substantial household clustering, active case finding and quarantine outside the home. Disease control measures should be adjusted to account for probable substantial presymptomatic transmission.
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