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Epidemiol Infect
. 2021 Jul 30;149:e173.
doi: 10.1017/S0950268821001643.
Charting elimination in the pandemic: a SARS-CoV-2 serosurvey of blood donors in New Zealand
Lauren H Carlton 1 , Tiffany Chen 1 , Alana L Whitcombe 1 , Reuben McGregor 1 , Greg Scheurich 2 , Campbell R Sheen 3 , James M Dickson 4 , Chris Bullen 5 , Annie Chiang 5 , Daniel J Exeter 5 , Janine Paynter 5 , Michael G Baker 6 , Richard Charlewood 2 , Nicole J Moreland 1
Affiliations
- PMID: 34668464
- DOI: 10.1017/S0950268821001643
Abstract
New Zealand has a strategy of eliminating SARS-CoV-2 that has resulted in a low incidence of reported coronavirus-19 disease (COVID-19). The aim of this study was to describe the spread of SARS-CoV-2 in New Zealand via a nationwide serosurvey of blood donors. Samples (n = 9806) were collected over a month-long period (3 December 2020-6 January 2021) from donors aged 16-88 years. The sample population was geographically spread, covering 16 of 20 district health board regions. A series of Spike-based immunoassays were utilised, and the serological testing algorithm was optimised for specificity given New Zealand is a low prevalence setting. Eighteen samples were seropositive for SARS-CoV-2 antibodies, six of which were retrospectively matched to previously confirmed COVID-19 cases. A further four were from donors that travelled to settings with a high risk of SARS-CoV-2 exposure, suggesting likely infection outside New Zealand. The remaining eight seropositive samples were from seven different district health regions for a true seroprevalence estimate, adjusted for test sensitivity and specificity, of 0.103% (95% confidence interval, 0.09-0.12%). The very low seroprevalence is consistent with limited undetected community transmission and provides robust, serological evidence to support New Zealand's successful elimination strategy for COVID-19.
Keywords: COVID-19; New Zealand; SARS-CoV-2; Spike; elimination; receptor binding domain; seroprevalence; serosurvey.