Twice evasions of Omicron variants explain the temporal patterns in six Asia and Oceania countries

Abstract

Background: The ongoing Coronavirus 2019 (COVID-19) pandemic has emerged and caused multiple pandemic waves in the following six countries: India, Indonesia, Nepal, Malaysia, Bangladesh and Myanmar. Some of the countries had been much less studied in this devastating pandemic. This study aims to assess the impact of Omicron variant in these six countries and estimate the infection fatality rate (IFR) and the transmission rate β(t) in the unit of basic reproduction number R 0 (t) in these six South Asia, Southeast Asia and Oceania countries.Method: We propose a Susceptible-Vaccinated-Exposed-Infectious-Hospitalized-Death-Recovered model with a time-varying transmission rate to fit the multiple waves of COVID-19 pandemic in the aforementioned six countries. The level of immune evasion and the intrinsic transmissibility advantage of Omicron variant is also estimated in this model.Results: We fit our model to the reported cases well. We estimate the IFR (in the range of 0.016% to 0.136%) and the transmission rate β(t) in the unit of basic reproduction number R 0 (t) (in the range of 0 to 9) in the six countries. The multiple pandemic waves in each country are observed in our simulation results.Conclusions: The invasion of Omicron variant caused the new pandemic waves in the six countries. The higher R 0 (t) suggests the intrinsic transmissibility advantage of Omicron variant. Our model simulation forecast implies that the Omicron pandemic wave may be mitigated due to the increasing immunized population and the vaccine coverage.

The Impact of COVID-19 Vaccination Campaign in Hong Kong SAR China and Singapore

“…We adopted an S À S V À E À I À H À D À R model from (Chen et al, 2022) (see Fig. 2) and fitted the model to the weekly COVID-19 deaths (the data) in Hong Kong and Singapore via the state-of-the-art R package POMP (King, 2017).…”

“…We omit the model equations in this work since they were given in previous works (Chen et al, 2022) and supplementary material. Vaccination rates (second dose/fully vaccinated and third dose/booster) are calculated based on data (Hannah Ritchie, 2020), after processing (ie, converting from per capita to per unvaccinated) as described in (Feng et al, 2022).…”