How do we best relax control measures as vaccine coverage for SARS-CoV-2 rises?

Abstract

h 2 The COVID-19 pandemic has significantly altered movement nd behaviour patterns of populations across the world. To reduce isease spread, countries have enacted varying levels of control easures, such as border restrictions, mask mandates, and social istancing policies. 1 Given the rising rates of SARS-CoV-2 vaccinaion, a key challenge for each country is to determine the optimal peed to relax control measures at, as domestic vaccine coverage ncreases. In The Lancet Regional Health – Western Pacific , Trung guyen and colleagues 2 use mathematical modelling to analyse ow different vaccination strategies interact with control measures o affect COVID-19 transmission in New Zealand (NZ). NZ faces unique considerations in relaxing control measure due o its extremely effective pursuance of a “zero-COVID policy”. 3 hroughout the pandemic, NZ has used strong applications of borer closure policies and lockdowns to maintain long periods withut community spread. This has resulted in incredibly successul disease mitigation, with New Zealand being one of the only igh-income countries to achieve a negative excess death rate in 020. 4 However, this also means that NZ has low rates of infectionnduced immunity, increasing the vaccine coverage required to chieve broad population-level protection and potentially altering uture transmission dynamics. 5 Given this, there is a strong need o model how reopening the NZ border might affect domestic disase transmission – motivating Nguyen et al .’s work. The core dynamics of disease spread within a population are ypically modelled using well-established compartmental models. o account for country-specific factors, these models often account or the age-stratification of the population and age-specific contact ixing patterns. Nguyen et al. used a model of this class to simlate how age-structured vaccine allocation programs (i.e., priori-