How contact tracing works

The Ministry of Health and district health boards will continue to trace people who may have been in contact with anyone who has COVID-19.

How contact tracing works

If someone has COVID-19, the Ministry of Health and district health boards (DHBs) find people who may have been in contact with them to see if they have also been infected. This process is called contact tracing.

There are 2 types of contacts:

  • close contacts
  • casual contacts.

Health services will give advice to both of these types of contacts on what they need to do.

The Ministry of Health has more information about contact tracing, including:

  • contact tracing phone calls
  • definitions of close contacts and casual contacts
  • informative fact sheets.

How the Ministry of Health and district health boards trace people who have been in contact with a case of COVID-19 (external link)

Locations of interest and casual contacts

Locations of interest are places where someone confirmed with COVID-19 visited.

If you visited a location of interest at a certain time, you may be classed as a casual contact. The Ministry of Health lists locations of interest and has advice on what you should do if you are a casual contact. 

Locations of interest in New Zealand (external link)

Contact tracing using the NZ COVID Tracer app

The NZ COVID Tracer app is our fastest way of responding to the virus — the faster we respond, the faster we stop it. The app also keeps people informed of the risk.

How contact tracing works using the NZ COVID Tracer app

1. COVID-19 is detected in the community

Usually this is from a test, someone visiting a doctor when ill or calling Healthline.

2. The person with COVID-19, and people living and working with them, are interviewed

They will be asked if they have used the official NZ COVID Tracer app to scan QR codes:

  • If they have, this gives us all the information needed to quickly start pinpointing the source of a cluster/community transmission and anyone else who may have been exposed to the virus. It also helps if they have also taken notes for those times when the QR code wasn’t available.
  • If they haven’t, there's a much more lengthy process to find out the same answers. This slows things down considerably, allowing COVID-19 more time to spread to others in the community.

3. An alert may be issued on the app

  • If the person was using the app and scanning QR codes, we can be certain of where they were at exact times. An alert can be issued via the app, warning others of the risk.
  • If they weren’t using the app, an alert probably won’t be able to be sent — to avoid sending false alerts and worrying people needlessly.

4. Others who receive the alert self-assess and decide whether to contact Healthline

  • If an alert does go out, anyone who has been using the app instantly receives information telling them they may have been exposed to COVID-19. They then self-assess whether they, or anyone they know, has symptoms, and get in touch with Healthline if they do.
  • People who don’t have the app won’t be able to receive the alerts. That means there may be a delay before they find out if there is a threat of the virus in their community.

How you can help

You can help make contact tracing easier for health officials by continuing to keep a record of where you go and who you meet.

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