Case definition and testing guidance for COVID-19

Case definition and testing guidance for health practitioners based on expert advice from the Ministry of Health's Technical Advisory Group.

Last updated: 30 October 2020

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See also: New Zealand COVID-19 Surveillance Plan and Testing Strategy


Strategic tools for early identification

The overarching public health COVID-19 strategy for New Zealand is to eliminate COVID-19. We must identify and manage cases and contacts early and be aggressive with the management of clusters. 

The tools available to use are:

  • testing
  • quarantine
  • self-isolation
  • timely contact tracing.

The Ministry has developed testing guidance to support the health sector in testing for COVID-19 to help us identify those with COVID-19 as early as possible. 

  • The highest priority for testing is those who are symptomatic and meet the HIS criteria, all of whom should be tested.
  • Table 1 provides guidance on other groups that are essential to test. It is critical to encourage all patients presenting with symptoms consistent with COVID-19 to be tested, irrespective of region. This message remains unchanged.
  • Only those meeting both the clinical and the HIS criteria will need to be notified to the Medical Officer of Health on presentation.
  • Those meeting both the clinical and the HIS criteria will be asked to self-isolate while awaiting test results. In addition, at Alert Levels 3 and 4, anyone else with symptoms who is tested should also self-isolate while awaiting test results
  • There is new advice around the testing of asymptomatic individuals. Please see table 2.
  •  The assessment and swabbing for those covered by this guidance is at no charge to the individuals.
  • DHBs may operate ‘pop-up’ testing facilities in your community, including for additional testing of asymptomatic people.

Case definition

The case definition document identifies those with a higher risk of having COVID-19 and outlines the reporting and self-isolation requirements for those with symptoms who meet the Higher Index of Suspicion (HIS) criteria.

Refer to the testing guidance for advice on who to test. The testing guidance will be regularly updated, however, those with symptoms who meet the higher index of suspicion criteria should always be the highest priority for testing.

Clinical criteria

The following symptoms are consistent with COVID-19.

Any acute respiratory infection with at least one of the following symptoms (with or without fever):

  • new or worsening cough
  • sore throat
  • shortness of breath
  • coryza 1
  • anosmia 2 .

Higher Index of Suspicion (HIS) criteria

Either, in the 14 days prior to illness onset have:

  • had contact 3 with a confirmed or probable case
  • had international travel
  • had direct contact with a person who has travelled overseas (eg, Customs and Immigration staff, staff at quarantine/isolation facilities)
  • worked on an international aircraft or shipping vessel
  • cleaned at an international airport or maritime port in areas/conveniences visited by international arrivals
  • anyone who has exited an MIQ facility within the last 14 days (excluding recovered cases), or
  • any other criteria requested by the local Medical Officer of Health.

This reflects the current COVID-19 situation in New Zealand and that at this stage, our greatest risk of re-introduction of COVID-19 and spread, is via our border. 

For a definition of close and casual contacts see Contact tracing.

Less typical symptoms

Some people may present with less typical symptoms such as only fever, diarrhoea, headache, myalgia, nausea/vomiting, or confusion/irritability.

If there is not another likely diagnosis, and they meet the HIS criteria, then test.

Case definition


Testing guidance

It is important that you continue to encourage all patients presenting to primary or secondary care with symptoms consistent with COVID-19 to be tested, regardless of whether they meet the HIS criteria or not. This advice applies to people living everywhere in New Zealand.

The assessment and swabbing for these patients are at no charge to the individuals.

We particularly encourage you to test the groups listed in Table 1.

It is critical to encourage all patients presenting with symptoms consistent with COVID-19 to be tested, irrespective of region.

Table 1: Guidance for primary and secondary care on essential groups for testing

Who

Action

Has symptoms of COVID-19 and meets the higher index of suspicion (HIS) criteria, as follows:

In the 14 days prior to illness onset, person has:

  • had contact with a confirmed or probable case
  • had international travel
  • had direct contact with a person who has travelled overseas (eg. Customs and Immigration staff, staff at quarantine/isolation facilities)
  • worked on an international aircraft or shipping vessel
  • cleaned at an international airport or maritime port in areas/conveniences visited by international arrivals
  • anyone who has exited an MIQ facility within the last 14 days (excluding recovered cases), or
  • any other criteria requested by the local Medical Officer of Health

Test and notify the Medical Officer of Health. The individual must self-isolate while test is pending, irrespective of Alert Level.

Meets the HIS criteria, and has one or more of the following less typical symptoms: fever, diarrhoea, headache, myalgia, nausea/vomiting, or confusion/irritability, and there is not another likely diagnosis.

Test and notify the Medical Officer of Health. The individual must self-isolate while test is pending, irrespective of Alert Level.

Has symptoms of COVID-19. Does not meet the HIS criteria.

Test. Stay home if unwell. Isolate while test is pending at Alert levels >2; no need to self-isolate at Alert leve1 1 or 2  while awaiting test results.

Table 2: Testing in asymptomatic people

Who Action

Does not have symptoms of COVID-19. Does not meet HIS criteria but are:

  • Health workers, including Aged Residential Care workers
  • Hospitality workers, including hotel, restaurant staff
  • Public-facing tourism workers
  • Public-facing transport workers (e.g. bus, taxi, uber)
  • Close contact of border worker groups

Offer testing if they present to your service.

No need to self-isolate while awaiting test result.

Asymptomatic border worker groups. This includes those who work at Managed Isolation and Quarantine Facilities 

Test as per Border Order.

No need to self-isolate while awaiting test result.

Asymptomatic close contacts of a confirmed or probable case

Test as per advice from public health unit.

Asymptomatic New Zealand-based air crew*

Test

*View more information on requirements for international airline crew.

Guidance for primary and secondary care on essential groups for testing

Surveillance plan and testing strategy


Self isolation guidance

Anyone who meets the clinical and HIS criteria should be tested, self-isolate while awaiting test results and be notified to the public health unit.
 
Anyone who is sick should be advised to stay home while they are unwell. 

Areas of New Zealand at Alert Levels 1 and 2 

At Alert Levels 1 and 2, only people who have symptoms and meet the HIS criteria need to self-isolate while awaiting test results.

All people with symptoms should stay at home if unwell and follow the advice of their health practitioner.

Areas of New Zealand at Alert Levels 3 and 4 

At Alert Levels 3 and 4, all people who meet the clinical criteria who are tested should self-isolate while awaiting test results.

Only those meeting the HIS criteria need to notified to the Medical Officer of Health.

Asymptomatic testing

Those who meet the HIS criteria who are asymptomatic do not need to self-isolate while waiting for test results, unless they are advised otherwise, for example if they are still completing their 14 days self-isolation requirement as a close contact of a confirmed case.

Household members of close or casual contacts

Household members of:

  • close or casual contacts who are asymptomatic, do not currently have to self-isolate 
  • close or casual contacts who are symptomatic, should self-isolate until the close or casual contact's test result is known. 

Casual contact definition

A casual contact is defined as someone who has had contact with a person while they were infectious with COVID-19, but doesn't meet the criteria for a close contact. We define who is considered a close contact in our Advice for Health Professionals.

Casual contacts of a confirmed (or probable) case do not routinely need to be tested or self-isolate if asymptomatic. They should be advised to monitor their health for 14 days and to isolate themselves immediately if any symptoms develop and phone Healthline or their GP to arrange to be tested.

For casual contacts with no symptoms there are no restrictions on movements (aside from any that already apply due to the current Government alert level). However, there are situations where a Medical Officer of Health may advise casual contacts to isolate and get tested in the absence of symptoms, and only come out of self-isolation once they have a negative test result. This will be contingent on consideration by public health officials. 

Casual contacts who are at higher risk of severe illness (eg, immunocompromised, people with co-morbidities) do not require additional public health follow-up. 


COVID-19 Instructions on specimen collection 

Guidance on how to take nasopharyngeal, and oropharyngeal + anterior nasal specimens for COVID-19.


1 Coryza – head cold e.g. runny nose, sneezing, post-nasal drip.

2 Anosmia – loss of sense of smell.

3 Refer Advice for Health Professionals for close contact criteria.

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