Case definition and clinical testing guidelines for COVID-19

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

Last updated: 2 March 2021

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See also: Testing plan and testing guidance


Strategic tools for early identification and management

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 containment and management of clusters. 

The tools available to use are:

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

The Ministry has developed clinical guidelines for testing 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 for testing in primary care. It is critical to encourage all people presenting with symptoms consistent with COVID-19 to be tested.
  • Table 2 provides guidance for testing in hospitals including emergency departments.
  • Only those meeting both the clinical and the HIS criteria will need to be notified to the Medical Officer of Health on presentation.
  • If you have symptoms of COVID-19 and are tested, you need to self-isolate while awaiting the test results.
  • 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 clinical guidelines for testing for advice on who to test. The testing guidelines 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 – head cold (eg, runny nose, sneezing, post-nasal drip)
  • anosmia – loss of sense of smell.

Higher Index of Suspicion (HIS) criteria

A higher index of suspicion for COVID-19 is indicated if any of the following are met in the 14 days prior to illness onset:

  • contact 1 with a confirmed or probable case
  • international travel
  • 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
  • exited an MIQ facility (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 definitions of Close, Close Plus, Casual Plus 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


Clinical guidelines for testing

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.

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

Table 1: Testing in primary care

Presentation

Action

Symptomatic

Higher index of suspicion

Typical symptoms

  • Test
  • Notify the Medical Officer of Health
  • Self-isolate1 while test result is pending, stay at home while unwell

Less typical symptoms with no other likely diagnosis

No higher index of suspicion

Typical symptoms

  • Test2
  • Self-isolate1 while test result is pending, stay at home while unwell

Asymptomatic

Contact of a confirmed or probable case

  • Test on advice from Ministry of Health and/or public health unit

Border worker including managed isolation or quarantine facilities

  • Test as per Border Order3

New Zealand-based air crew

  • Test as per requirements4

Close Contact of a border worker

  • Offer test

Individual that works in any of the following settings:

  • Health care including aged residential care
  • Hospitality
  • Public-facing tourism
  • Public-facing transport (eg, bus, taxi, Uber)
  • Offer test
  1. More information is available under Self-isolation guidance.
  2. Testing can be omitted if on clinical assessment there is another clear cause, not a transmissible respiratory infection.
  3. More information on Border Orders is available at Epidemic notice and Orders.
  4. More information on requirements for international airline crew is available at Aviation sector.
Table 2: Testing in hospital including emergency departments

Presentation

Action

Symptomatic

Higher index of suspicion

Typical symptoms

  • Test
  • Notify the Medical Officer of Health
  • Isolate while test result is pending

Less typical symptoms with no other likely diagnosis

Not at higher index of suspicion

Typical symptoms

  • Test1
  • Manage as per local infection prevention and control protocols
  1. Testing can be omitted if on clinical assessment there is another clear cause, not a transmissible respiratory infection.

Testing plan and testing guidance

View the Testing plan and testing guidance.


Self-isolation guidance and notification to a public health unit

Anyone who is tested should self-isolate at home while awaiting their test results.

Anyone who meets the clinical and HIS criteria should be tested, self-isolate at home while awaiting test results and be notified to the public health unit.

Read more about self-isolation at home.

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 or Close Plus Contact of a confirmed (or probable) case.

Household members of Close Plus Contacts

Household secondary contacts:

  • Close Plus Contacts meet the same criteria for Close Contacts however, their contact was where there is higher risk for transmission. 
  • All household secondary contacts (and others at the discretion of the Medical Officer of Health) stay at home until the primary Close Plus Contact has a negative day 5 test result.
  • If the primary Close Plus Contact develops symptoms after day 5, the household should stay at home until a further negative test result is received.

Household members of Close Contacts

Household secondary contacts:

  • If the primary Close Contact becomes symptomatic, then their household contacts should stay at home until the primary Close Contact returns a negative test result (following symptom onset)
  • If one or more secondary household contact(s) becomes symptomatic, they should stay at home and get a test
  • If the primary Close Contact is asymptomatic, the secondary household contacts do not currently have to stay at home 

Casual Plus Contacts

People who have had exposure to a confirmed (or probable) case, but who do not meet the criteria of a Close Contact. For Casual Plus Contacts, their contact was where there is higher risk for transmission. Any person who receives a yellow QR notification for a location of interest via the NZ COVID Tracer app where the notification says, ‘Casual Plus Contact’.

Casual Plus Contacts of a confirmed (or probable) case should be advised to stay at home, get a test around Day 5 after their last exposure and stay at home until a negative test result is received. Phone Healthline for testing advice and continue to self-monitor for COVID-19 symptoms for 14 days. 

Casual Contacts

A Casual Contact is defined as someone who has had contact with a confirmed (or probable) case while the case was infectious with COVID-19, but doesn't meet the criteria for a Close Contact or any person who receives a yellow QR notification for a location of interest via the NZ COVID Tracer app where the notification says, ‘Casual Contact’.

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 stay at home and if any symptoms develop phone Healthline or their GP immediately 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 Refer Advice for Health Professionals for Close Contact criteria.

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