Operationalisation of Model for Dynamics of COVID-19 in Kenya: Trajectory of Omicron Wave in Kenya

Abstract

Kenya has experienced five COVID-19 surges driven by Alpha, Beta, Delta (2x), and Omicron. These waves are accurately predicted by the OTOI-NARIMA model. Consequently, in Kenyan Lake Region Economic Bloc (LREB), private sector and NGO partnerships have been forged to strengthen regional health systems and prepare effectively for epidemic resurgence. The co-development and implementation of the so-called “LREB COVID-Dx” digital platform enable efficient epidemic monitoring in semi-real time, referral of patients, optimal use of limited resources, and community of practice among regional health practitioners. In this paper, we describe the practical implementation of the OTOI-NARIMA model and COVID-Dx digitized platform in Kenyan COVID-19 reality, with emphasis on the latest Omicron wave. In estimating the trajectory of Omicron wave, 612 data points of daily case infections are used. The order of moving average is calculated and corresponds to reproduction number, R0. The series are normalized, superimposed, and used to derive OTOI-NARIMA model. The model is estimated and interpreted. Test statistics including Ljung-Box test, ACF, and PACF are conducted. The COVID-Dx data digitization is used to inform epidemic preparedness. The OTOI-NARIMA model in general successfully established the periodicity and seasonality of COVID-19 resurgences in Kenya. The model is used to inform preparedness, including vaccines rollout. During alert stages of the wave, on December 4, 2021, the model was reused to nowcast the trajectory of the wave. Omicron wave was projected to peak in Kenya between November 23, 2021, and January 4, 2022. The wave showed strong likelihood of declining after January 29, 2022. In reality, Omicron wave was experienced from November 27, 2021, to January 29, 2022. The model predicted that Omicron variant will have run its full course by June 22, 2022, and possibly replaced by another variant, recombinant or sub-variant. According to OTOI-NARIMA model, dominant variants are replaced after every six months, which gives insights into suitable periods for administration of vaccine boosters. The total number of Kenyan patients (symptomatic or asymptomatic) during Omicron resurgence was estimated to be ~4.5 million. The total number of patients hospitalized during the wave is estimated to be ~2000. Effective, efficient, and economical response to Omicron resurgence in LREB benefitted from meticulous infusion of mathematical modelling and digitization of relevant data for epidemic preparedness and rapid decision making. The study has two limitations: Incomplete merging of stochastic processes and deterministic methods; calculating with accuracy the period it takes to fully replace a dominant COVID-19 variant. These two limitations may be considered for further research.