Waning of immunity following COVID-19 vaccination presents a challenge when attempting to model likely population impacts of COVID-19 policy options
Joshua Szanyi, Tim Wilson, Nick Scott, Tony Blakely


Immunity to SARS-CoV-2 following vaccination wanes over time in a non-linear fashion, making modelling of likely population impacts of COVID-19 policy options challenging. We observed that it was possible to mathematize non-linear waning of vaccine effectiveness (VE) on the percentage scale as linear waning on the log-odds scale, and developed a random effects logistic regression equation based on UK Health Security Agency data to model VE against Omicron following two and three doses of a COVID-19 vaccine.


Vaccine effectiveness on the odds scale reduced by 47% per month for symptomatic infection after two vaccine doses, lessening to 35% per month for hospitalisation. Waning on the odds scale after triple dose vaccines was 35% per month for symptomatic disease and 19% for hospitalisation.

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First published: May 26, 2022
Population Interventions Unit
The Population Interventions Unit is a research group at the University of Melbourne that investigates health and cost impacts of population interventions.