The Costs and Benefits of Covid-19 Lockdowns in New Zealand

This paper considers the costs and benefits of New Zealand’s Covid-19 nation-wide lockdown strategy relative to pursuit of a mitigation strategy in March 2020. Using data available up to 28 June 2021, the estimated additional deaths from a mitigation strategy are 1,750 to 4,600, implying a Cost per Quality Adjusted Life Year saved by locking down in March 2020 of at least 13 times the generally employed threshold figure of $62,000 for health interventions in New Zealand; the lockdowns do not then seem to have been justified by reference to the standard benchmark. Using only data available to the New Zealand government in March 2020, the ratio is similar and therefore the same conclusion holds that the nation-wide lockdown strategy was not warranted. Looking forwards from 28 June 2021, if a new outbreak occurs that cannot be suppressed without a nation-wide lockdown, the death toll from adopting a mitigation strategy at this point would be even less than had it done so in March 2020, due to the vaccination campaign and because the period over which the virus would then inflict casualties would now be much less than the period from March 2020; this would favour a mitigation policy even more strongly than in March 2020. This approach of assessing the savings in quality adjusted life years and comparing them to a standard benchmark figure ensures that all quality adjusted life years saved by various health interventions are treated equally, which accords with the ethical principle of equity across people.