Analysis by Keith Rankin.
The above chart plots estimates of vaccine-induced immunity to Covid19, for five countries, including three in Europe currently in the news for their most recent wave of covid infections and deaths.
Essentially, I give a score of 0.5 for each vaccine shot; and I assume that immunity wanes by 0.4% per day, starting 20 days after receipt of a vaccine shot.
On 9 November, in this story, Covid-19: Experts at odds over move to traffic light system, Melbourne-based New Zealand epidemiologist Tony Blakely refers to ‘the community’s “peak immunity”‘. Essentially, he was referring to vaccination-induced immunity, where there is a waxing as ‘jabs’ are given, and a waning (especially) in the period between second and third vaccine doses.
The chart shows Germany and Austria attaining peak vaccination immunity in August, soon after the ‘delta variant’ became the dominant variant of Covid19 in Europe. For Ireland, the peak was in early September.
Australia and New Zealand are just approaching ‘peak immunity’ now, so early December is precisely the ideal time to ‘open up’, as Blakely argues. Further, as third doses roll out from the end of November, New Zealand stands to maintain that peak through the summer holiday period, and into the risky period in February and March when secondary and tertiary education gets underway.
That vaccination-induced immunity will be topped up, also, by a degree of natural immunity arising from increased exposure to the virus, and not just to the vaccine.
Austria, Germany and Ireland are all countries which imposed substantial border restrictions, lockdowns and mask mandates; their immunity arising from natural exposure is – like New Zealand and Australia – comparatively low. Though Austria and Germany did have some residual natural immunity from the ‘alpha strain’ wave which hit Europe in March and April. They missed out on a major wave of ‘delta’ mainly because they were at peak immunity in August. (See chart below, for German cases and deaths.)
But all three of these countries are now facing waning immunity – fading vaccination immunity as well as fading immunity from the alpha wave. It is that immunity loss, plus the onset of winter, that appears to be driving their current covid emergencies; not the delta strain. (While the delta strain is still the dominant strain, waning immunity rather than the delta strain would appear to be the driving force.)
Of note here was a report from Ireland in the TVNZ 6pm News (Saturday 13 Nov). One health professional there commented, Jacinda Ardern style, that the new covid wave was “expected”; however, he said, what did surprise was “how rapidly” immunisation was waning. Ireland’s vaccination immunity was indeed waning – as the above chart shows – though was still higher than Austria and Germany. However, Ireland – like New Zealand and Australia – was unusually reliant on vaccines, given that its last substantial covid outbreak was in January and that it had endured a very long period of immunity-sapping public health restrictions.
Germany is an interesting case study, in large part because it was reputed to have managed Covid19 best among European countries in 2020. (Refer to my Covid19 deaths, the German case, 30 Oct 2021.) Germany looks bad in 2021, with deaths consistently and significantly above what they would have been in the absence of the pandemic.
In this new chart for Germany, we see four episodes of excess deaths which do not match the recorded Covid19 deaths: August 2020, May 2021, August 2021, October 2021. The last three episodes probably do relate to Covid19, probably cases of under-recording of covid deaths. The 2020 episode was in August, and matches a pattern through which some kind of infectious disease has a summer peak. This death peak may have been linked to a non-covid virus. (There was an unusual death peak in Belgium, France and Netherlands at the same time.)
We also note that there were three periods in which public health measures significantly brought down Germany’s death rate: July 2020, February/March 2021, and May 2021. We can understand higher later death rates as ‘postponed deaths’.
Germany’s situation is worrying; as are those of Austria and Ireland. The second Germany chart above shows that daily covid cases are now at a record high, and well above the reported world average.
Nevertheless, I am confident that concerted – albeit late – revaccinations will see these countries avoid the carnage that is taking place further east in Europe. We wait and see, however, whether obstinate vaccine-resistant behaviour sees another prolonged winter wave in west Europe. We would like to see vaccination-induced immunity in the European Union reaching Australasian levels.
Keith Rankin (keith at rankin dot nz), trained as an economic historian, is a retired lecturer in Economics and Statistics. He lives in Auckland, New Zealand.
