Is the mortality after vaccination in Norway a concern?

Norwegian health authority reported that 33 people had died after receiving the first dose of Pfizer-BioNTech Covid-19 vaccine [1]. The news has generated concern and even fear among the general community. However, my evaluation suggests that the fear is not founded.

It is hard to make sense out of the 33 deaths without knowing the number of vaccinated people. According to The Age, Norway has vaccinated approximately 42,000 elderly people, mostly in nursing homes. Thus, the one-week risk of mortality is 0.078%.

Is the 0.078% risk too high? No. In a study published in PLoS ONE, the investigators followed 690 Norwegian nursing home residents for 3 years, and they found that the risk of mortality during the first 6 months was 17% [2]. This translates into a risk of 0.65% per week, 8-fold greater than the risk of vaccine-associated mortality.

One way to appreciate the risk of mortality is to apply the concept of ‘micromort’ [3]. A micromort is defined as one in a million chance of death. So, if an intervention that results in 10 deaths per 1 million population per year, then the micromort for the intervention is 10. We can compare the micromort among vaccinated people and the general population.

According to the newspapers, most (75%) of those who died aged 80 years and older. The Norwegian population lifetable shows that the 1-year probability of mortality among people aged 80 years is 38.917% [4], or 1066 micromorts.

Now, back to the Norwegian case, there were 33 deaths among 42,000 vaccinated people. These unfortunate people died shortly after (eg within 5 days) receiving the jab. We can estimate the number of micromorts as: 33 / (0.042 * 5) = 157.

In other words, among those aged 80+ years the micromorts associated with vaccination was 85% lower than that in the general population. It is therefore reasonable to say that the vaccine is fairly safe. Still, this is only one side of the evaluation based on a small number of events, and we cannot say anything about the causal relationship between vaccination and post-vaccination mortality.

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[1] https://www.theage.com.au/world/europe/norway-finds-no-direct-link-between-elderly-deaths-and-vaccine-20210119-p56v3c.html

[2] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0203480#pone-0203480-t002

[3] Spiegelhalter D. Using speed of ageing and “microlives” to communicate the effects of lifetime habits and environment. BMJ 2012;345:e8223-e8223.

[4] https://www.ssb.no/en/statbank/table/07902/tableViewLayout1

osteoporosis | epidemiology | genetics | biostatistics | data enthusiast

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