Taiwan ended third COVID-19 community outbreak as forecasted

Area of Science:

• Epidemiology
• Public Health
• Mathematical Modeling

Background:

• Accurate forecasting of community outbreaks is crucial for effective resource allocation and implementing non-pharmaceutical interventions.
• Societal and economic recovery hinges on predicting the end of outbreaks for resuming normal operations.
• Taiwan experienced three distinct COVID-19 community outbreaks between 2019 and 2021.

Purpose of the Study:

• To forecast the end of the third COVID-19 community outbreak in Taiwan.
• To validate a novel forecasting method using a key control variable.
• To assess the effectiveness of contact tracing in controlling outbreaks.

Main Methods:

• Identified the ratio of 7-day average local & unknown confirmed to suspected cases as the key control variable.
• Utilized an exponential model to forecast the outbreak's end date.
• Compared forecasted dates with real-world observations of case confirmation and quarantine.

Main Results:

• The exponential model forecasted the end of the third outbreak on August 16th.
• Real observations crossed the threshold eleven days later, on August 27th.
• The last case was confirmed and quarantined on September 20th, demonstrating the method's accuracy.

Conclusions:

• The proposed forecasting method, utilizing the case ratio, accurately predicts the end of local outbreaks.
• The case ratio serves as an indicator for the effectiveness of contact tracing efforts.
• Effective contact tracing, testing, and isolation are critical for ending community outbreaks.