Covid 19 coronavirus Delta outbreak: Why 7000 Aucklanders need to be tested per day

Public health officials are focusing on seven suburbs which may have undetected positive cases in the community. Photo / Brett Phibbs

The message for Aucklanders to get tested is only growing louder as the region's alert level 4 lockdown drags on.

Now into its 29th day, cases are remaining low with 15 new community infections in Auckland yesterday.

However, the level of surveillance testing aimed to detect any hidden transmission is being repeatedly touted as one of the key tools the Government can use to build safe passage for Aucklanders to enter alert level 3 next week.

Last week, director general of health Dr Ashley Bloomfield said the benchmark for good surveillance testing is 7000 swabs taken per day in the City of Sails.

That 7000 figure is said to be close to the total number of Aucklanders who are experiencing symptoms consistent with Covid-19.

Instead of being plucked from thin air, this number is determined through FluTracker - a Ministry of Health tool which surveys 10,000s of people each week to measure influenza-like illness activity.

In its latest report for the week ending September 5, about 933 of 46,674 people surveyed (0.2 per cent) nationwide reported having a fever and cough.

There is plenty of capacity for testing across Tāmaki Makaurau. Photo / Michael Craig

The ministry estimates 3 per cent of Aucklanders are experiencing flu-like symptoms per week currently.

Using a city population estimate of 1.7 million, that equates to 51,000 people.

Per day, that's roughly 7000 people (7285) who need to submit for a swab.

In the last 10 days, testing has fluctuated with notable drops over the weekend and stronger numbers through the week.

Number of tests reported in Auckland (figures cover 24-hour period prior to 1pm on day of reporting):

• Sunday (Sept 5): 2592

• Monday: 2088

• Tuesday: 5852

• Wednesday: 8566

• Thursday: 8472

• Friday: 7974

• Saturday: 7196

• Sunday: 4928

• Monday: 4250

• Tuesday (yesterday): 7823

The days with excess of 8000 tests administered have been helped in part by the ministry's surveillance testing of essential workplaces - which has returned no positive results from any asymptomatic staffers.

Public health officials are now focusing on seven Auckland suburbs as they attempt to isolate any remaining community transmission.

They are Mt Eden, Massey, Māngere, Favona, Ōtara, Papatoetoe and Manurewa.

Most critical to reach are those with symptoms but the call has also gone out to asymptomatic residents, who may be harbouring the virus but yet to develop a sniffle or a sore throat.

For information on testing locations, visit the Auckland Regional Public Health Service website.