COVID-19 in NZ: Did you think my “predictions” were bad? What do you think of these scenarios/ modelling?


In this post we look at reports released yesterday on the Ministry of Health (MOH) website.

The reports can be found here:


We comment mainly on the first and last of these reports.

We suggest you read the reports.

We include excerpts (from the two reports mentioned) below:







In the two reports we see:

  • In the worst case scenario 27,600 would be expected to die.
  • The likely number of deaths is expected to be between 12,600 and 33,600.
  • The peak week in one scenario is 21 weeks after introduction.

We note the current number of deaths worldwide today from this site:

The other stats I use are also from the above site.

The countries are ranked by the number of deaths (4th column) in the table below:


Italy currently has the highest number of deaths (12,428), followed by Spain (8,464).

China currently has 3305 deaths and is likely to have less than 3400 in total from this outbreak.

Can we really expect New Zealand to have more than 3.7 times the number of deaths that China has or more than Italy has presently?

Yet this is the lower range value.

New Zealand has a population of less than five million people (4.96 million is mentioned in the draft report).

Today Italy and Spain currently have 206 and 181 deaths per one million of their respective populations.

Apart from San Marino (766) and Andorra (155), the next highest is Belgium and the Netherlands both with 61.

The next two highest appear to be France with 54 and Switzerland with 50.

The next highest is Luxembourg with 37.

Are the authors really suggesting that New Zealand will have at least 2,500 deaths per one million people (12,600/5) or 6,700 deaths per one million people using their upper range value (33,600/5)?

We can only hope that 12,600 ends up being an upper limit.

Do you like the way the Report figures end in 600?

A summary mentions Ro=2.2 (read R-zero) which indicates one person will infect 2.2 other people if there is no isolation. With isolation Re is usually used.

Ro= 1.5 is used in their models. This would appear to be low. It is unlikely COVID-19 can be compared to previous pandemics impacting on the NZ population.

An animation uses Ro=2.6 to show that a Coronavirus can out-spread from 5 to 368 people in 5 Cycles (Credit: The New York Times) If 5 people with new coronavirus can impact 2.6 others, then 5 people could be sick after 1 Cycle, 18 people after 2 Cycles, 52 people after 3 Cycles and so on.


A report also mentions the peak week in one scenario is 21 weeks after introduction.

We note that China would have been over its cases in about 50 days (7 weeks) had it not been for:

  • Over 5,000 people still remaining in a serious/ critical condition
  • People returning to China bringing back COVID-19
  • A possible secondary infection (dismissed by China).

Sometimes models need to be compared to existing situations overseas to see if they reflect reality.

I hope we do not get COVID-19.

I am pleased New Zealand has acted quickly to go into Lockdown last week.

Please stay within your bubble.

Alan Grace
1 April 2020

My posts can be found here:

Data for my posts can be found at:

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