The current case classification and clinical criteria for COVID-19 can be found on the Ministry of Health website: https://www.health.govt.nz/our-work/diseases-and-conditions/covid-19-novel-coronavirus/covid-19-information-health-professionals/case-definition-and-clinical-testing-guidelines-covid-19

The laboratory criteria for COVID-19 can be found on the same page in the document under the subheading Case definition. To meet the epidemiological criteria a case contact must be laboratory-confirmed according to the guidelines in the country of diagnosis.

Guidelines for notifying historical cases

If a COVID-19 case is suspected to be historical, the case should remain classified as ‘Under investigation’ in EpiSurv until it is confirmed to be an historical infection according to the Ministry of Health protocol. The PHU must also determine if the infection was previously notified overseas.

• If a case has a ‘weak’ positive result in New Zealand and proof of diagnosis as a case overseas, the status should be made ‘Not a case’ (indicating the infection has already been reported in a different country, therefore should not be added to the total worldwide case count and not counted as a case in New Zealand).

• If a case has a ‘weak’ positive result in New Zealand and there is no evidence (by either documentation or recall) of diagnosis as a case overseas, the status should be made ‘Confirmed’ (indicating the infection was discovered for the first time in New Zealand, therefore should be added to the total worldwide case count and counted as a case in New Zealand).