Fig. 1: Reported daily cases and wastewater data between 1 January 2022 and 31 March 2023 in Aotearoa New Zealand.

a Reported daily cases of COVID-19. The black line shows the adjusted case series with the multiplicative day-of-the-week effect removed (see Supplementary Material Section 1.2). b SARS-CoV-2 genome copies per person per day in sampled wastewater. The two outliers in wastewater data arise from estimates of a high wastewater flow rate in Wellington following high rainfall. Since rainfall is a source of noise in wastewater sampling, we retain these samples in our analysis. c Proportion of the total population covered by sampled wastewater catchments. Reported case data were obtained from the New Zealand Ministry of Health²⁷ and wastewater data were obtained from ESR²⁸.