Projecting COVID‐19 intensive care admissions in the Netherlands for policy advice: February 2020 to January 2021

Abstract

Model projections of COVID‐19 incidence into the future help policy makers about decisions to implement or lift control measures. During 2020, policy makers in the Netherlands were informed on a weekly basis with short‐term projections of COVID‐19 intensive care unit (ICU) admissions, which were produced using an age‐structured transmission model. A consistent, incremental update procedure that integrated all new data was conducted on a weekly basis. First, up‐to‐date estimates for most parameter values were obtained through re‐analysis of all data sources. Then, estimates were made for changes in the age‐specific contact rates in response to policy changes. Finally, a piecewise constant transmission rate was estimated by fitting the model to reported daily ICU admissions, with a change point analysis guided by Akaike's Information Criterion. This procedure allowed us to make weekly projections, accounting for recent and future policy changes, and to adapt the estimated effectiveness of the policy changes based only on the natural accumulation of incoming data.