  Aotearoa New Zealand implemented a Covid-19 elimination strategy in 2020 and
2021, which enabled a large majority of the population to be vaccinated before
being exposed to the virus. This strategy delivered one of the lowest pandemic
mortality rates in the world. However, quantitative estimates of the
population-level health benefits of vaccination are lacking. Here, we use a
validated mathematical model to investigate counterfactual scenarios with
differing levels of vaccine coverage in different age and ethnicity groups. The
model builds on earlier research by adding age- and time-dependent case
ascertainment, the effect of antiviral medications, improved hospitalisation
rate estimates, and the impact of relaxing control measures. The model was used
for scenario analysis and policy advice for the New Zealand Government in 2022
and 2023. We compare the number of Covid-19 hospitalisations, deaths, and years
of life lost in each counterfactual scenario to a baseline scenario that is
fitted to epidemiological data between January 2022 and June 2023. Our results
estimate that vaccines saved 6650 (95% credible interval [4424, 10180]) lives,
and prevented 74500 [51000, 115400] years of life lost and 45100 [34400, 55600]
hospitalisations during this 18-month period. Making the same comparison before
the benefit of antiviral medications is accounted for, the estimated number of
lives saved by vaccines increases to 7604 [5080, 11942]. Due to inequities in
the vaccine rollout, vaccination rates among M\=aori were lower than in people
of European ethnicity. Our results show that, if vaccination rates had been
equitable, an estimated 11-26% of the 292 M\=aori Covid-19 deaths that were
recorded in this time period could have been prevented. We conclude that
Covid-19 vaccination greatly reduced health burden in New Zealand and that
equity needs to be a key focus of future vaccination programmes.
