TITLE:
Estimating the Level of Asymptomatic COVID-19 Infections in Northern Ireland in 2020
AUTHORS:
Peter A. Hall, Gabor Kiss, Tilman Kuhn, Salissou Moutari, Ellen Patterson, Emily Smith
KEYWORDS:
Pandemic, Epidemic, SARS-CoV-2, COVID-19, Compartmental Model, SEIAR Model, Basic Reproduction Number, Effective Reproduction Number, Parameter Estimates, Fitted Model, Testing Uncertainty, Asymptomatic Infection, Northern Ireland
JOURNAL NAME:
Open Journal of Modelling and Simulation,
Vol.10 No.2,
April
28,
2022
ABSTRACT: The identification and understanding of COVID-19
potential routes of transmission are fundamental to informing policies and
strategies to successfully control the outbreak. Various studies highlighted
asymptomatic infections as one of the silent drivers of the epidemic. An
accurate estimation of the asymptomatic cases and the understanding of their contribution to the spread of the disease
could enhance the effectiveness of current control strategies, mainly based on
the symptom onset, to curb transmission. We investigate the dynamics of the
COVID-19 epidemic in Northern Ireland during the period 1st March 25th to December 2020 to estimate
the proportion of the asymptomatic infections in the country. We extended our
previous model to include the stage of the asymptomatic infection, and we
implement the corresponding deterministic model using a publicly
available dataset. We partition the data into 11 sets over the period of study
and fit the model parameters on the consecutive intervals using the cumulative
number of confirmed positive cases for each
interval. Moreover, we assess numerically the impacts of uncertainty in testing and we provide estimates of the
reproduction numbers using the fitted parameters. We found that the
proportion of asymptomatically infectious subpopulations, in Northern Ireland during the period of study,
ranged between 5% and 25% of exposed individuals. Also, the estimate of the
basic reproduction number, R0, is 3.3089. The lower and upper estimates for herd immunity are
(0.6181, 0.7243)
suggesting that around 70% of the population of Northern Ireland should acquire
immunity via infection or vaccination, which is in line with estimates reported
in other studies.