Timing of Antiviral Treatment Initiation is Critical to Reduce SARS-CoV-2 Viral Load

CPT Pharmacometrics Syst Pharmacol. 2020 Sep;9(9):509-514. doi: 10.1002/psp4.12543. Epub 2020 Aug 7.


We modeled the viral dynamics of 13 untreated patients infected with severe acute respiratory syndrome-coronavirus 2 to infer viral growth parameters and predict the effects of antiviral treatments. In order to reduce peak viral load by more than two logs, drug efficacy needs to be > 90% if treatment is administered after symptom onset; an efficacy of 60% could be sufficient if treatment is initiated before symptom onset. Given their pharmacokinetic/pharmacodynamic properties, current investigated drugs may be in a range of 6-87% efficacy. They may help control virus if administered very early, but may not have a major effect in severely ill patients.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antiviral Agents / pharmacology
  • Antiviral Agents / therapeutic use*
  • COVID-19 Drug Treatment*
  • Humans
  • Lopinavir / pharmacology
  • Lopinavir / therapeutic use
  • Models, Theoretical
  • Ritonavir / pharmacology
  • Ritonavir / therapeutic use
  • SARS-CoV-2 / drug effects
  • SARS-CoV-2 / physiology*
  • Severity of Illness Index
  • Singapore
  • Treatment Outcome
  • Viral Load / drug effects


  • Antiviral Agents
  • Lopinavir
  • Ritonavir