The impact of re‐opening the international border on COVID‐19 hospitalisations in Australia: a modelling study

• Published in: Medical journal of Australia Vol. 216; no. 1; pp. 39 - 42
• Main Authors: Hanly, Mark J, Churches, Timothy, Fitzgerald, Oisin, Post, Jeffrey J, MacIntyre, C Raina, Jorm, Louisa
• Format: Journal Article
• Language: English
• Published: Australia John Wiley and Sons Inc 17-01-2022
• Subjects: Adolescent; Adult; Aged; Australia - epidemiology; Communicable Disease Control - methods; Communicable Disease Control - statistics & numerical data; Communicable Diseases, Imported - epidemiology; Communicable Diseases, Imported - virology; Computer Simulation; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 - virology; COVID‐19; Disease Outbreaks; Disease transmission; Epidemiology; Epidemiology and Research Design; Female; Health Services Administration; Health systems; Hospitalization - statistics & numerical data; Humans; infectious; Infectious Diseases; Male; Middle Aged; Public health; Research and Reviews; Risk management; SARS-CoV-2; statistical; Statistics; Vaccination Coverage - statistics & numerical data; Young Adult; Australia; COVID-19; infectious; statistical; Disease transmission; Health systems; Models; Risk management; Epidemiology; Public health
• ISSN: 0025-729X; 1326-5377
• DOI: 10.5694/mja2.51291

Objective
To estimate the numbers of COVID‐19‐related hospitalisations in Australia after re‐opening the international border.
Design
Population‐level deterministic compartmental epidemic modelling of eight scenarios applying various assumptions regarding SARS‐CoV‐2 transmissibility (baseline R0 = 3.5 or 7.0), vaccine rollout speed (slow or fast), and scale of border re‐opening (mean of 2500 or 13 000 overseas arrivals per day).
Setting
Simulation population size, age structure, and age‐based contact rates based on recent estimates for the Australian population. We assumed that 80% vaccination coverage of people aged 16 years or more was reached in mid‐October 2021 (fast rollout) or early January 2022 (slow rollout).
Main outcome measures
Numbers of people admitted to hospital with COVID‐19, December 2021 ‒ December 2022.
Results
In scenarios assuming a highly transmissible SARS‐CoV‐2 variant (R0 = 7.0), opening the international border on either scale was followed by surges in both infections and hospitalisations that would require public health measures beyond mask wearing and social distancing to avoid overwhelming the health system. Reducing the number of hospitalisations to manageable levels required several cycles of additional social and mobility restrictions.
Conclusions
If highly transmissible SARS‐CoV‐2 variants are circulating locally or overseas, large and disruptive COVID‐19 outbreaks will still be possible in Australia after 80% of people aged 16 years or more have been vaccinated. Continuing public health measures to restrict the spread of disease are likely to be necessary throughout 2022.