Viral Replication

Understanding Peak Viral Replication

Study Design:

In a post exposure prophylaxis study, a modeling analysis was performed in a cohort of patients who developed incident SARS-CoV-2 infection. That analysis compared magnitude of peak viral load, time from viral shedding onset to peak, and time from peak to shedding cessation across three symptom groups. The analysis estimated and compared the time from peak viral load to onset of mild or moderate symptoms for people in the symptomatic groups. Peak viral load generally occurred within 1-2 days of symptom onset.1 Viral replication peaks rapidly, followed by a slow decrease, suggesting that the period for effective antiviral intervention is very narrow.1

Select Study Limitations:

Self-sampling technique or degradation of sample could yield false negatives. Analysis was limited to a 14 day observation period, which underestimates viral shedding. Daily swabbing could have missed peak viral load in those with shorter viral shedding duration. Detectable viral RNA does not equal culture positivity or infectiousness. Study relied on Ct values as a proxy for viral RNA levels. The viral shedding model used assumed that viral load followed a piecewise linear trend whereas the true trajectories might be more curved.

Image of Potential Viral Replication Timing in SARSCoV-2 Based on Meta-Analysis of 13 Studies Image of Potential Viral Replication Timing in SARSCoV-2 Based on Meta-Analysis of 13 Studies

Visualization of peak viral replication early in disease course is for illustrative purposes only, based on the Stankiewicz study. Not drawn to scale.