Relaxing restrictions at the pace of vaccination increases freedom and guards against further COVID-19 waves

TL;DR

This study uses a detailed epidemiological model to determine how quickly countries can safely lift COVID-19 restrictions in line with vaccination progress, emphasizing the importance of high vaccine uptake and targeted measures.

Contribution

It introduces an age-stratified SEIRD-ICU model to quantify safe restriction easing rates aligned with vaccination, considering various scenarios and highlighting the importance of seroprevalence and targeted interventions.

Findings

Steady restriction easing is possible by autumn 2021 with vaccination progress.

High vaccine uptake is crucial to prevent future severe waves.

School-based measures remain important due to children’s susceptibility.

Abstract

Mass vaccination offers a promising exit strategy for the COVID-19 pandemic. However, as vaccination progresses, demands to lift restrictions increase, despite most of the population remaining susceptible. Using our age-stratified SEIRD-ICU compartmental model and curated epidemiological and vaccination data, we quantified the rate (relative to vaccination progress) at which countries can lift non-pharmaceutical interventions without overwhelming their healthcare systems. We analyzed scenarios ranging from immediately lifting restrictions (accepting high mortality and morbidity) to reducing case numbers to a level where test-trace-and-isolate (TTI) programs efficiently compensate for local spreading events. In general, the age-dependent vaccination roll-out implies a transient decrease of more than ten years in the average age of ICU patients and deceased. The pace of vaccination determines the speed of lifting restrictions; Taking the European Union (EU) as an example case, all considered scenarios allow for steadily increasing contacts starting in May 2021 and relaxing most restrictions by autumn 2021. Throughout summer 2021, only mild contact restrictions will remain necessary. However, only high vaccine uptake can prevent further severe waves. Across EU countries, seroprevalence impacts the long-term success of vaccination campaigns more strongly than age demographics. In addition, we highlight the need for preventive measures to reduce contagion in school settings throughout the year 2021, where children might be drivers of contagion because of them remaining susceptible...