COVID Odyssey: Winter Warning NZ 18 ~ Delta variant: NZ vs Norway~ How may % vaccination affect case numbers?

We use Norway data to estimate a worst-case scenario for Norway and New Zealand. We anticipate we could have 500,000 cases over a one-year period and 2100 deaths.

Even using Norway’s actual case data provides a scary scenario for New Zealand.

New modelling prepared for the Government by Professor Shaun Hendy suggests that New Zealand could see up to 7000 Covid-19 deaths a year even with a high proportion (75%) of the population (fully) jabbed.

Hendy projects it [Delta-19 variant of COVID-19] would cause 60,000 hospitalisations and 7000 deaths over a one-year period.

If 90 per cent of the 5+ population was reached however – around 85 per cent of the full population – then deaths would drop to around 50 over a year, with just 50,000 cases.

See:

https://www.stuff.co.nz/national/health/coronavirus/300414146/covid19-nz-modelling-suggests-7000-deaths-in-a-year-even-with-75-per-cent-of-country-jabbed

Hendy estimated that over 1m people (1.15m people) could get infected over a one-year period.

Also see:

Covid-19 NZ: Rodney Jones says Shaun Hendy’s 7000-death vaccine model doesn’t pass plausibility test

We analyse Norway COVID-19 data and apply the results to New Zealand.

Norway

We see that the daily growth, r (and hence Re), in COVID-19 cases in early 2020 for both countries is almost the same:

NorwayNZ

See:

NZCOVIDWorldAllCasesCPMrNew

COVID Odyssey: Spring Spruce up 33 ~ Post#916: NZ Delta COVID-19~ Hendy’s Worst case scenario: 7,000 deaths in 12 months

COVID Odyssey: Worldwide Winter Windup 5 ~ Revised estimates for Re worldwide

Norway has a slightly bigger population than New Zealand (5.473m vs 5m) and a greater land size (385,207 km² vs 268,021 km²).

Therefore Norway has about 14.2 people per square kilometre and new Zealand has 18.7.

In Norway 83.4 % of the population is urban (4,521,838 people in 2020).

In New Zealand 86.9 % of the population is urban (4,191,405 people in 2020).

See:

https://www.worldometers.info/world-population/norway-population/

https://www.worldometers.info/world-population/new-zealand-population/

https://www.worldometers.info/coronavirus/

We can consider the countries comparable.

We can use Norway to estimate a worst-case scenario for New Zealand.

On 22 September 2021, Norway had a total of 184,609 cases and 850 deaths. See:

NorwayCases

https://www.worldometers.info/coronavirus/country/norway/

This equates to around 217.2 cases for each death.

We use the total of 184,609 cases as a high estimate for a yearly number of cases for Norway and hence New Zealand.

We could use 850 as an estimate for the number of possible deaths in New Zealand.

Alternatively, on 22 September 2021, Norway had 799 new cases and 9 deaths. We realise that the people who died are likely to have been infected some days earlier.

This is around 0.011264 deaths per case or 88.8 cases per death, much less than the 217.2 cases per death above.

For the 184,609 cases in Norway, this would equate to 2080 (2100) deaths. Compare this with the current 850 deaths in Norway. 2100 is almost 2.5 x 850. Our approximations are generous.

We multiply the estimated 2080 deaths by the 217.2 above to get an estimated 451,629 cases.

We add on 10% to get 496,793 cases which we round to 500,000 cases.

We therefore estimate that Norway and hence New Zealand (even when the fully vaccinated level reaches 67%) could have a total of 500,000 cases in one year and 2100 deaths.

Compare this with the 1.3m cases and 7,000 deaths estimated by Hendy.

Norway has around 2/3 of its population (67%) fully vaccinated. New Zealand has around half this percentage (34%).  See:

https://ourworldindata.org/covid-vaccinations?country=OWID_WRL

We can therefore use Norway’s figures to estimate a worst-case scenario for New Zealand.

We consider our estimate is better than the estimate produced by Hendy.

Clearly the situation will improve considerably when New Zealand obtains a vaccination rate (fully vaccinated) of 75%, 80%, and 90%.

Consequently Professor Hendy’s estimates appear to be out by at least a factor of three when compared to our own estimates. To provide a worst-case scenario our own approximations are easily double realistic figures for Norway.

Even using Norway’s actual case data provides a scary scenario for New Zealand.

Please do your part and get your jabs.

Norway’s present 850 deaths and 184,609 cases could be obtainable in New Zealand in less than two years since they have already occurred in Norway. See:

https://www.worldometers.info/coronavirus/country/norway/

Looking over the past month, Norway has had about 40 deaths and 35,000 cases. This annualised is roughly 480 deaths and 420,000 cases.

Maybe consider a scenario of an estimated 500 deaths and Norway’s current 185,000 cases for both Norway and New Zealand over a one-year period when the population is at least 60% fully vaccinated.

Alternatively we can just look at New Zealand statistics.

In the first month of the current Delta outbreak in New Zealand there were about 1,000 cases. Annualised this would be 12,000 cases.

We currently have 4135 cases and 27 deaths. 12,000 cases would mean about 80 deaths.

We could also use the current statistics to estimate a worst-case scenario.

Which of the above do you think provides the most suitable worst-case scenario?

See:

COVID Odyssey: Spring Spruce up ~ Delta variant NZ ~ How may vaccination rates affect a worst-case scenario?

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