Asymptomatic carriers of the virus display no clinical symptoms but are known to be contagious.
Recent evidence reveals that this sub-population, as well as persons with mild symptoms, represent a major contributor in the propagation of COVID-19. The asymptomatic sub-population frequently escapes detection by public health surveillance systems.
Because of this, the currently accepted estimates of the basic reproduction number (Ro) of the virus are inaccurate. It is unlikely that a pathogen can blanket the planet in three months with an Ro in the vicinity of 3, as reported in the literature.
A new study presents a mathematical model taking into account asymptomatic carriers. Results indicate that an initial value of the effective reproduction number could range from 5.5 to 25.4, with a point estimate of 15.4, assuming mean parameters.
The first three weeks of the model exhibit exponential growth, which is in agreement with average case data collected from 13 countries with universal healthcare and robust communicable disease surveillance systems; the average rate of growth in the number of reported cases is 23.3% per day during this period.
Link to the paper: https://doi.org/10.1101/2020.03.18.20037994
Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.