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, April 11

The latest in our new series of charts, graphics and data visualisations by Chris McDowall.

This work is entirely funded by the generosity of The Spinoff Members

These posts collate the most recent statistics and present them as charts and maps. The Ministry of Health typically publishes data updates in the early afternoon, which describe the situation at 9am on the day of release. These data visualisations are interactive – use your mouse or thumb to hover over each graph for more detail.

Note for users of The Spinoff app: if the charts below are not appearing, please update your app to the latest version.

Caroline McElnay, the director of public health, announced two more deaths related to Covid-19. This means that overnight the number of deaths related to the virus doubled, from two to four.

This afternoon’s Ministry of Health figures report that the total number of confirmed and probable Covid-19 cases stands at 1,312 (1,035 confirmed and 277 probable). A total of 422 people have recovered, an increase of 49 since yesterday.

There were 20 new confirmed cases reported in the last 24 hours and nine new probable cases. There are now 13 significant clusters with 10 or more cases, up from 12 yesterday. The new cluster is an aged residential care facility in Christchurch.

There are 15 people in hospital. That includes five in intensive care units – one each in Wellington, Middlemore, Hawke’s Bay, Dunedin and North Shore hospitals. The Dunedin patient is in critical condition.

Yesterday, 3,061 tests were processed. The ministry reported averaging 3,619 Covid-19 lab tests per day during the week ending April 10. A total of 58,746 lab tests have been conducted since March 9. There are 53,042 test supplies in stock.

This chart compares active and recovered cases. Active cases are people who currently have the Covid-19 virus. Recovered cases are people who had the virus, but are at least 10 days since onset and have not exhibited any symptoms for 48 hours.

Once again there was a slight decrease in the number of active cases – from 908 active cases yesterday down to 886 this morning. Aside from a slight uptick on Wednesday, the active cases total has trended slowly downwards for the last six days.

The symbol map shows confirmed and probable Covid-19 cases arranged by district health board. Southern (207), Waitematā (183), Auckland (173) and Waikato (167) remain the four district health boards with the largest number of active cases.

There are now 13 significant clusters, up from 12 yesterday. The new cluster is a second aged residential care facility in Christchurch.

This chart shows confirmed and probable cases by their date of report. A few people got in touch to ask why this chart does not quite line up with the daily counts that get reported at the media conference. Yesterday the ministry provided further details on what “date of report” means in their detailed statistics:

The number of cases reported on a particular date may not match the number of cases reported in the last 24 hours. This is because the number of confirmed and probable cases reported in the last 24 hours includes cases which were entered on an earlier date as “under investigation” or “suspected” whose status has now been changed to confirmed or probable.

This clarification is helpful. The daily media briefing outlines all the cases that were classified as probable or confirmed in the last 24 hours. However, many of the “new” daily cases will actually have been in the health system for a few days already as potential instances of Covid-19.

The chart above shows cases according to their “date of report” rather than the “date the case was classified as confirmed/probable”. This is a subtle but important distinction.

It remains unclear precisely what event triggers someone to record the “date of report”. I suspect that it’s the first time a potential case enters the health system, but that is speculation on my part. I will write again to the ministry, asking for further clarification.

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