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A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness
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Effect of asymptomatic transmission and emergence time on multi-strain viral disease severity

Amir Reza Alizad-Rahvar1, Mehdi Sadeghi2

  • 1School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran.

Plos One
|October 7, 2022
PubMed

Insights

A new, more contagious virus strain (higher R0) doesn't always dominate or increase disease severity. Asymptomatic transmission and emergence timing are crucial factors determining viral spread and outcomes.

Area of Science:

  • Epidemiology
  • Virology
  • Mathematical Modeling

Background:

  • Viral epidemics can be complicated by the emergence of new, more transmissible strains.
  • Increased transmissibility (higher R0) often raises concerns about greater disease severity.

Purpose of the Study:

  • To investigate if a more contagious strain necessarily dominates and increases disease severity.
  • To analyze the impact of asymptomatic transmission and emergence time on epidemic outcomes.

Main Methods:

  • A mathematical model simulating a 2-strain viral epidemic was developed.
  • Computer simulations were used to explore various scenarios.

Main Results:

  • Basic reproduction number (R0) alone is insufficient to predict a new strain's dominance or impact.
  • A highly transmissible strain with significant asymptomatic transmission can reduce overall mortality.
  • The emergence time of a new strain is critical; earlier emergence favors its dominance.

Conclusions:

  • Predicting the outcome of new viral strains requires considering R0, asymptomatic transmission rates, and emergence timing.
  • These factors collectively determine disease prevalence, severity, and the dominant strain.

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