key: cord-0897702-z8yjc37u
authors: Carlton, L. H.; Chen, T.; Whitcombe, A. L.; McGregor, R.; Scheurich, G.; Sheen, C. R.; Dickson, J. M.; Bullen, C.; Chiang, A.; Exeter, D. J.; Paynter, J.; Baker, M. G.; Charlewood, R.; Moreland, N. J.
title: Charting Elimination in the Pandemic: A SARS-CoV-2 Serosurvey of Blood Donors in New Zealand
date: 2021-04-19
journal: nan
DOI: 10.1101/2021.04.12.21255282
sha: bae1cd63b1efa28d63762d05f3ce158e69f6ca4d
doc_id: 897702
cord_uid: z8yjc37u

A large-scale SARS-CoV-2 serosurvey of New Zealand blood donors (n=9806) was conducted at the end of 2020. Seroprevalence, after adjusting for test sensitivity and specificity, was very low (0.1%). This finding is consistent with limited community transmission and provides robust evidence to support New Zealand's successful elimination strategy for COVID 19.

New Zealand has a strategy of eliminating SARS-CoV-2 that has resulted in a low 24 incidence of coronavirus-19 disease (COVID-19). The first case was reported on February 26 th 25 2020, and the country entered a strict nationwide lockdown one month later for 49 days (1). 26 Through rigorous border control and managed isolation and quarantine facilities for new arrivals, 27 New Zealand has since remained largely COVID-19 free. Globally, serological surveillance has 28 been utilized throughout the pandemic to define cumulative incidence, including estimations of 29 missed cases and/or asymptomatic infection. Due to lockdowns and movement restrictions, blood 30 donors have been used as a sentinel population in many settings (2,3). The aim of this study was 31 to describe the spread of SARS-CoV-2 in New Zealand via a blood donor serosurvey. Though the 32 pandemic response has been highly effective, PCR testing was initially restricted due to limited 33 diagnostic reagents (4) and there have been occasional border incursions and small community 34 outbreaks, including a cluster in August 2020 with no identified link to the border. (Table 1 and Appendix). This study was assessed by the 42 Health and Disability Ethics Committee, and additional consent was not required (21/CEN/21).

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The copyright holder for this preprint this version posted April 19, 2021. ; https://doi.org/10.1101/2021.04.12.21255282 doi: medRxiv preprint Antibodies to the Spike (S) protein and receptor-binding domain (RBD) persist for many 44 months after infection, compared with antibodies to the nucleocapsid (N) protein (5,6), providing 45 rationale for the use of S protein-based assays in serosurveys. The overall serological testing 46 algorithm was optimized for specificity given the low number of reported COVID-19 cases in 47 New Zealand (2,190 as of January 6 th 2021) and the associated period prevalence of 0.04%, which 48 limits the positive predictive value of tests with reduced specificity (7). Samples were first 49 screened with a widely used and well-validated 2-step ELISA that comprises a single point dilution 50 assay against the RBD followed by titration against trimeric S protein (Appendix) (8,9). Samples 

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Successful Elimination of Covid-19

Transmission in New Zealand

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The first 12 months of COVID-19: a timeline 109 of immunological insights

Evaluation of serological tests for SARS-CoV-2: Implications for serology testing in 112 a low-prevalence setting. J INFECT DIS. 2020 Aug 6.

. CC-BY-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) Journal of the RCPA (in press).

124 . CC-BY-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) CC-BY-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) CC-BY-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)The copyright holder for this preprint this version posted April 19, 2021. ; https://doi.org/10.1101/2021.04.12.21255282 doi: medRxiv preprint