The Government hasn't used Bluetooth tracing to check whether people have been exposed to any new cases since the first day of the outbreak, Marc Daalder reports

The Government has not made use of a contact tracing function that Covid-19 Response Minister Chris Hipkins described as a "tool that will help to speed up contact tracing".

When Bluetooth tracing was added to the NZ COVID Tracer app in December, Hipkins said, "This new Bluetooth functionality adds to the tools we already have and improves our chances of getting on top of any potential outbreak quickly – as long as we use them."

However, the Government has not used the tool since the first day of the outbreak.

Bluetooth tracing works by registering proximity to another person using Bluetooth. If someone tests positive for Covid-19, their unique and anonymised Bluetooth "key" can be added to a server. Everyone else's app will then check to see if that key is one they've been close to and will notify any potential contacts.

While QR code scanning can identify potential exposures in specific locations, Bluetooth can catch contacts within locations of interest and outside of them - such as at a bus station, or waiting for an elevator, or even passing someone on the street. A spokesperson for the Ministry of Health said over 3900 people had been notified of exposure via a QR code scan in this latest outbreak.

However, the spokesperson said, fewer than 10 people have been notified of an exposure by Bluetooth. It now turns out that's because keys were last uploaded to the server on August 17 - the day the first case was detected.

No more exposure checks have been run since, according to digital contact tracing expert Andrew Chen.

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Director-General of Health Ashley Bloomfield said contact tracers had not been asking new cases for their Bluetooth keys, but that he'd "given them a nudge around that".

"Bluetooth use has been included in five recent training sessions for public health and contact tracing staff run by the Ministry of Health recently," the ministry spokesperson said.

Bloomfield also said that the bulk of the cluster were of demographics not likely to use the Bluetooth function. But, as of the start of the outbreak, more than 1.5 million New Zealanders were actively using Bluetooth tracing, making it unlikely that none of the new cases had the function enabled.

"Currently information from Bluetooth hasn’t been used by Public Health Services.  Anecdotal reports are that for many of the cases detected, Bluetooth hasn’t frequently been used or investigated thoroughly," the ministry spokesperson told Newsroom.

They indicated the Government had made an intentional decision not to use Bluetooth tracing in the first stage of the outbreak.

"At the early stages of an outbreak, this information can be very general and requires a considerable amount of sifting through to rule out inadvertent links, such as individuals in different vehicles stationary at traffic lights, or in slow moving traffic, or individuals in different rooms but where the phones interpret that as being close," the spokesperson said.

"As the outbreak changes, and more emphasis goes onto fewer locations, the Ministry will be working with public health units to assess whether Bluetooth activation with positive cases in the small number of workplaces (seven to date) may assist."

The news comes after the Government was criticised for failing to increase contact tracing surge capacity ahead of the latest outbreak, despite four reviews urging it to do so.