Director of health Ashley Bloomfield, who reads the numbers that will define how the rest of this year plays out (Illustration: Simon Chesterman)

Covid-19: New Zealand cases mapped and charted, August 12

One bright spot amid the grimness of the Covid resurgence: the return of our series of charts, graphics and data visualisations of the pandemic by Chris McDowall.

Over one hundred days, Covid-19 slowly slipped from my attention. I was aware of new cases reaching Aotearoa’s border, managed isolation breaches, relapses in Australia and growing concern that few people were using contact tracing apps, but it felt like we had the virus under control. Shortly after 9pm last night, four positive tests of unknown origin turned my complacency upside-down. Wishing for a thing does not make it so.

Last night prime minister Jacinda Ardern and deputy general of health Ashley Bloomfield announced that four people in one family in South Auckland had tested positive for Covid-19, with no known connection to overseas travel or mandatory isolation facilities. Midday today, Auckland moved to alert level three, with the rest of the country shifting to alert level two. These alert levels will remain until at least midnight on Friday.

So, how does that look through the numbers? This chart shows confirmed and probable Covid-19 cases since the country’s first reported case in late-February.

There is a fair bit going on here, but here is the main gist. Blue bars represent people who with confirmed or probable cases of Covid-19 with a reported history of international travel within 14 days of onset or someone in close contact with an overseas acquired case. The pink and burgundy bars are trickier. They represent people with no reported history of international travel within 14 days of onset and no recorded epidemiological link to an overseas source case.

Read the chart from left to right and observe the basic patterns. During most of March there’s a lot of blue when most of New Zealand’s cases came from overseas. In the second half of March, the pink and burgundy bars start getting longer and more frequent as community transmission begins and the sources become hazier. This trails off through April and May until we reach the late-May, early-June quiet period.

In the second half of June, more people start arriving from overseas, some of whom test positive for the virus. These are the blue cases through the extend through the winter period.

Now cast your eye to the pink/burgundy bar at the far right of the chart. Eight locally acquired cases, all linked but where one source is unknown. The unknown history of contact and potential transmission behind that little data tower is what has health professionals so concerned.

This chart compares active and recovered cases. Active cases are confirmed or probable cases of Covid-19 where the person has neither recovered nor died. Recovered cases are people who were once an active case, but are at least 10 days since onset and have not exhibited any symptoms for 48 hours.

The cases are less evident here as it compares the relatively small number of active cases to the total number of people who have recovered. It is a useful reminder though of the overall pattern and cadence of Covid-19 in Aotearoa.

This chart shows the last few months through the lens of Covid-19 tests. We see a steady ramping up between March and May, before a dip in at the start of June before a quick climb as more New Zealander return home from overseas. Expect to see a steep testing uptick over coming weeks.

Testing centres have been overwhelmed today. Seven new pop-up community testing centres (CTCs) opened in Auckland this afternoon, in addition to the four permanent centres and two pop-ups that opened this morning. This map shows where these testing centres are located.

Some of these testing centres offer walk-ins appointments, others require referral. Please consult this Auckland District Health Board information page for detailed information on opening hours and referral processes.

Please be careful and kind out there, everyone. Aucklanders are back in level three while the rest of the country is in level two. Wear a mask, minimise contact with people outside your bubble and record your movements in case you are needed for contact tracing.

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