Why say that 98.8% of Covid-19 deaths since February were not vaccinated doesn't make much sense

The data provided by the Higher Institute of Health is circulating. The statistic is correct, but it lends itself to misinterpretations: it does not mean that now only 1.2% of deaths are among the vaccinated

(Photo: Irwan Iwe / Unsplash) From Tuesday afternoon onwards many newspapers and Italian news agencies have taken up a report published by the Higher Institute of Health based on data updated to 21 July: an articulated 11-page document that reports various statistics and considerations on people who have died with a Covid-19 infection from the beginning February . The report was discussed above all with regard to a statistic, which made headlines, according to which in the period analyzed 98.8% of the deceased were without full vaccination coverage (with no dose or with only one dose administered), and therefore by subtraction, the people who died with a completed vaccination course were 1.2%. Often, however, the titles have proposed the percentage rounded to the unit: 99% against 1%.

This statistic might seem surprising, on a superficial reading, because it would seem even more flattering towards vaccines of all those previously circulated. But it does not mean that vaccines are 99% effective in preventing death from Covid-19, nor that in recent weeks only 1% of deaths are among the vaccinated. Moreover, the news was obtained from a data reported on page 9 of the document and to which the Higher Institute of Health gave more than marginal relevance, explicitly specifying that "this data cannot provide information about the effectiveness of vaccination, but it is provided for purely descriptive purposes ". As we will see, in fact, at the base there is a sampling problem that is anything but secondary.

The statistics, explained

Let's start with a trivial consideration, but useful to understand the following considerations: in 2020, 100% of deaths from Covid-19 were in the unvaccinated and 0 % concerned vaccinated people. A very insignificant statistic, given that as we know the Covid-19 vaccines were not available.

The theme of the percentages presented these days is exactly the same. The time range to which the statistics refers largely concerns a period in which the vaccinated were a decidedly marginal fraction of the Italian population. The report departure date of February 1st was chosen because it coincides with the time when the first vaccinated people in our country (all healthcare professionals) acquired double dose protection (at that time there was only the Comirnaty formulation available), and because the purpose of the study was to analyze the characteristics of people who died after completing the vaccination, but without the aim of creating a direct comparison between vaccinated and unvaccinated.

The data collected with this method tell us that between 1 February and 21 July there were 35,776 deaths in Italy, of which 423 involved people with a completed vaccination course. Which certainly leads us to say that in the reference period the deaths of vaccinated people were 1.2% of the total, but this has very little meaning in terms of vaccination efficacy.

To clarify the point enough a couple of data. About 17 thousand people died of Covid-19 between February and March, equal to 48% of the total for the period. At the end of March the vaccine doses administered in Italy reached 3.5 million (with a majority of first doses), therefore the vaccinated people were less than 1.5 million: a very small proportion compared to the total population. Similar speech for the following two months. Between April and May just over 16 thousand people died (equal to another 45% of the total for the period) and there were fewer than 6 million people with a complete vaccination course, i.e. more than 90% of the population was still without injected doses or with a single dose. In short, almost all the deaths included in this statistic correspond to a period in which the accinati were a small minority, therefore it makes no sense to claim to extract statistical information on vaccinations, whether good or bad they appear.

The actual data of vaccines and deaths

The most reliable Italian data we have to date, which is the one provided by the same Higher Institute of Health, is that the double dose of anti Covid-19 vaccine avoids the outcome fatal of the disease in 96% of cases. A very high percentage that gives excellent hope of lowering the burden on the hospital system and of containing the dramatic death toll, but which has nothing to do with the 99% issue. The ratio between the absolute numbers of deaths between the unvaccinated and the total deaths, in fact, is not a measure of the effectiveness of the vaccine, and moreover strongly depends on how many people are vaccinated.

As we have already had the opportunity to then tell, in perspective, it is very likely that it will come to the point that deaths among vaccinated will become more numerous than those among unvaccinated, especially when vaccinated people in our country will be a large majority and - as per the objectives of the campaign vaccination - will perhaps reach almost all. From the data of the latest weekly report of the Higher Institute of Health, in particular, it emerges that at the moment deaths among the unvaccinated are 69% of the total, therefore 31% are among the vaccinated. Not 99% and 1%.

The effect of the vaccination campaign by age group

Reading the statistics in this phase of the pandemic requires particular attention and method. For example, the fact that vaccination has started (after health workers) from the most elderly and fragile sections of the population can generate some statistical anomaly that should not be misled.

From the analysis of the data of the vaccinated people who died from Covid-19 it emerges that on average the age is higher than the general average (86.3 years against 80.0) and that the number of concomitant diseases is higher (3.7 against 3.0): a difference that can be explained - says the Higher Institute of Health - with the fact that the average age of the vaccinated is higher than the average age of the population, or with the hypothesis that the protective efficacy of the vaccine is lower for very old people, over ninety years old. And the first of the two explanations has a further data in favor: the general average age of deaths from Covid-19 is decreasing, and if in the first half of 2021 it was around 80 years, in recent weeks it is reaching 72.


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