Predicting The Outcome of The National Covid-19 Immunization Program: A Modeling Study

Introduction Malaysia rolled out the national COVID-19 immunization program in March 2021 aiming to eliminate the COVID-19 pandemic with 70% population immunity. The study aims to investigate the outcome of the immunization program at different vaccination rates and vaccine efficacy (VE).    

Methodology A two-dose compartmental vaccine model with herd effect was developed, calibrated, and parameterized using actual COVID-19 cases from 7 April to 31 May 2021. The model generated a baseline scenario prior to the third movement control order (MCO 3.0) with 70% and 90% VE for the first and second dose of vaccine, a vaccination rate of 24000 first dose per day (FDPD), and 6- and 12-month immunity coverage for both natural and vaccine immunity. The impact of different VE combinations at different vaccination rates was investigated.      

Results The surge of COVID-19 cases prior to the MCO 3.0 was characterized by a basic reproduction number of 1.51. Daily and active infections were expected to peak at 34971 cases per day and 424189 cases without the lockdown, respectively. To achieve total control by the end of 2021, the vaccination rate needs to be maintained above 100 000 FDPD. The new and active infections can be suppressed by 51.1% to 65.4% and 54.4% to 68.0% at 100 000 FDPD, and by 60.9% to 69.7% and 64.7% to 72.7% at 150 000 FDPD, respectively.    

Conclusion The MCO 3.0 accelerates the elimination of the pandemic. With the high vaccination rate, the COVID-19 pandemic can be significantly contained by the end of 2021.   

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