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THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE
MORTALITY IN EU IN 2021
AMACHINELEARNINGPERSPECTIVEBYPATRICKE.MEYER
Abstract. The question whether COVID-19 vaccines have no effect on all-
cause mortality or perform as intended, that is mainly reduce excess mortality,
has been debated recently in the scientific literature. By crossing the all-cause
mortality data with the vaccine data from public European databases, we
compare the impact on mortality of two variables of interest namely a vaccine-
dose-rate and a covid-case-rate. Using classical machine learning strategies and
graphical models, we are able to assess the conflicting hypothesis about the
effect of vaccines on all-cause mortality, at least in Europe. Our conclusions
differ for different age-categories investigated but, until a better predictive
variable is found, our results clearly suggest that the benefit-risk balance for
the 0-44 years old is not in favor of those vaccines.
1. INTRODUCTION
It can be sometimes difficult to navigate through the scientific literature when
we face studies reaching opposite conclusions. This typically happens when data
and subjects are new. Confronting hypothesis is a crucial part of the scientific
process. Recently, two statistical studies based on data from the UK have reached
the conclusion that COVID-19 vaccines may have no effect on the overall mor-
tality. In other words, those vaccines may save people from COVID-19 in the
same proportion than they may exacerbate other mortality causes [Crawford, 2021,
Neil and Fenton, 2021]. Those studies are thus disagreeing with another study con-
cerning US data and relayed on the CDC website [Xu et al., 2021]. Despite the fact
that those studies use data from different countries, it could be expected that those
reach similar conclusions rather than opposite ones. Assuming the same underlying
effects are at play and in order to favor one of those conflicting hypothesis, we have
attempted a machine learning approach to study the impact of those vaccines on
the all-cause mortality in EU. Indeed, we have downloaded the EuroMOMO data
giving the mortality z-scores of each age category across different EU countries
[EuroMOMO, 2021]. We have crossed those with the ECDC vaccination data that
also provide information by age category and countries. Finally, we extracted the
ECDC 14-day-case-positivity-rate and death-rate in each of the targeted country
[ECDC, 2021]. Next, combining graphical models with generalized linear models
and random forests [Whittaker, 1990, Hastie et al., 2001, Breiman, 2001], we have
evaluated the impact of a vaccine-dose-rate and a covid-case-rate variables on ex-
cess mortality of the current year. Our conclusions differ for different age-categories
investigated but for the young cohorts, our analysis favor the studies showing no
benefits from vaccination. We have discussed our results in the last section of this
paper.
Date: 28th December 2021.
1
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 2
2. DATA
As stated in the introduction, we downloaded the mortality data from [EuroMOMO, 2021]
and the vaccination data as well as the case-positivity-rate and deaths-poitivity-
rate from [ECDC, 2021]. Unfortunately the list of countries and the list of age
targets are not a perfect fit between our data sources. Hence, we have focused on
the countries and age categories were an intersection was possible without creating
strong distortions. There is a trade-offthat could have manifested here, on the one
hand removing too much data can lead us to a poor dataset in terms of number
of samples, on the other hand, introducing too much distortions could also lead us
to inaccurate conclusions. However, our intersecting data is already consequent.
Indeed, in the end, data from 18 EU countries could be kept as is, namely Austria,
Belgium, Cyprus, Denmark, Estonia, Finland, France, Hungary, Ireland, Israel,
Italy, Luxembourg, Malta, Norway, Portugal, Slovenia, Spain and Sweden. Unfor-
tunately data from Greece, Switzerland and UK were not present in both datasets.
Also, the variables first dose and second dose from the ECDC dataset appeared
incomplete for two countries: the Netherlands and Germany. Hence those five
countries present in the EuroMOMO data have been removed from our resulting
dataset.
In terms of age category, the EuroMOMO dataset has the 0-14, 15-44, 45-64,
65-74, 75-84 and 85+ age categories while the ECDC data have as target group :
0-4, 5-9, 10-14, 15-17, 18-24, 25-49, 50-59, 60-69, 70-79, 80+. As a result, grouping
the three first categories from the ECDC would match perfectly the 0-14 years
category of the EuroMOMO data. The three next age categories could also be
grouped to obtain a 15-49 age group matching closely the 15-44 category from the
first dataset. The next grouping 50-59 and 60-69 had an acceptable 5 years shift
from the first dataset. However, the other age categories were not attempted to be
matched in order to avoid too strong distortions from our age-matching strategy.
Hopefully, our analysis based on the population targeting the 0-64 years from 18
different EU countries could deliver us with sufficient evidence to favor one of the
contradicting hypothesis debated above. Each of the downloaded dataset provide
us with a weekly monitoring of their respective variables. We opted for grouping
by 4 weeks periods. It seemed logical to opt for a multiple of 14 days because the
case-positivity-rate and deaths-rate used by the ECDC dataset is precisely based
on 14-day period. Another reason for this particular choice is that the 52 weeks of a
year can be easily divided by 4. Finally, having a time-interval big enough to obtain
both a smoothing effect and a higher likelihood for capturing time-delayed effects
has been intended. Our data starts at week 46 of 2021 and goes down to week 47
of 2020 by groups of 4 weeks, that is for each variable. Other choices of starting
week could be chosen but 46 is the last week where we obtained data from all three
sources (1 dataset from all-cause mortality and 2 datasets from ECDC). Finally we
defined a new variable called DoseRate which is simply the sum of the number of
first doses and second doses of all the COVID-19 vaccines that were administered to
the targeted age-group during the 4-weeks-period, divided by the total population
of the targeted country. The age-targeted-population could have been a better
choice for our rate. However, since each age-category is treated separately, the
analysis should not suffer from this choice. Since age-categories are not a perfect
match in between the different data sources, we applied a crude corrective term on
the variable DoseRate for our third age-category (equivalent to remove 10% of the
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 3
total doses) to account for the fact that the 50-69 years old have likely received more
doses during each period than the 45-64 of interest. We also applied a corrective
term to our second age-group to account for the excess 5 years over the 34 years
involved in the 14-49 category (this corrective term thus amount to 5/34 of the
total doses received). Although those corrective terms are crude, the removal of
those appear to have no consequence on the subsequent statistical analysis. In
the end, we produced 3 datasets, one for each age category of the EuroMOMO
data treated (i.e. 0-14, 15-44, 45-64). Each dataset has 13 periods multiplied by 18
countries, hence 234 samples. There are 9 variables in total, namely ZscoresCurrent,
ZscoresPast1Y (i.e. mainly 2020), ZscoresPast2Y (i.e. mainly 2019), Where (i.e.
country), When (i.e. which group of 4 weeks), Target (i.e. age-category), DoseRate
(i.e. reflecting the administered doses during the period), CaseRate (i.e. average
ECDC 14-day-positivity-rate during the period) and CovDeathRate (i.e. average
ECDC 14-day-deaths-rate during the period). Our R script to extract data and
our resulting datasets are now freely available [Meyer, 2021].
3. ANALYSIS and METHODS
It must be emphasized that it is near impossible to perform a statistical anal-
ysis without making any assumption or without any bias. For example, the use
of the variable “all-cause mortality” introduces in itself many biases. What if a
higher rate of suicides become visible in the all-cause mortality not because of the
pandemic itself but because of the various political measures limiting freedoms?
What if cancer treatments have been delayed by the same political measures but
results in a higher death rate in the following years? What if crimes and accidents
increase because of some recovered freedom of movements from the feeling of safety
due to the vaccination campaign? Despite those weaknesses, not using the all-cause
mortality also suffer from many biases [Classen, 2021, Neil and Fenton, 2021]. For
example, what if the spike protein present in each COVID-19 vaccine has an in-
herent toxicity that do increase mortality through cardiac and/or cancer related
unknown mechanisms? What if crimes, accidents and suicides are in fact the con-
sequences of some neurological impact of a vaccination more than the results of
the various political measures taken? In the end, we might have to be humbly
conscious of the trade-offs that are connected to each choice of mortality measure
and state clearly the implicit assumptions behind those choices. For example, we
should pinpoint that [Xu et al., 2021] may also have made some choices that could
importantly bias their conclusion. For example, « To ensure comparable health-
care–seeking behavior among persons who received a COVID-19 vaccine and those
who did not (unvaccinated persons), eligible unvaccinated persons were selected from
among those who received 1 dose of influenza vaccine in the last 2 years. ». If
this choice indeed removes one bias w.r.t. healthcare seeking behavior, it could
well introduce other biases. It could preferentially select weaker population for the
younger cohort. Indeed we could argue that, at least in EU, young populations do
not make a wide use of the influenza vaccine unless they suffer from health issues
[Mereckiene, 2018]. Also [Xu et al., 2021] exclude all COVID19 deaths. This could
be a very delicate operation that the authors recognize themselves : « ...although
deaths associated with COVID-19 were excluded, causes of death were not assessed.
It is possible that the algorithm used might have misclassified some deaths associated
with COVID-19 because of lack of testing or because individual mortality reviews
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 4
were not conducted. ». Hence, the authors remove all deaths happening within 30
days of a COVID-19 diagnosis. If this choice could make sense to assess the efficacy
of any vaccine, it does not when it comes to assess the security of it. For example,
what if COVID-19 vaccines are the cause of a temporary drop in immunity that
would increase the probability of catching COVID-19?
In our analysis, we use the z-scores of excess mortality. Due to the limited amount
of variables investigated, we cannot eliminate all the biases connected to the use of
all-cause mortality measure. However, it is worth noting that the 18 EU countries
in our data have used different restriction measures, at different point in time of
the pandemic, and all have different healthcare providing services and capacities.
This could results into an averaging out of some biases. Indeed, it would be quite
astonishing (though not impossible) that suicides and crimes happen exactly at the
same moment with respect to either the viral waves or the vaccination campaign
in each country and also with a similar intensity. It should be clear also from the
data that we do not hold into account or adjust for socio-economic status, health
conditions and other confounders. We do not use either the standard mortality rate
(SMR) because we perform the same analysis for each age category separately. In
fact, we deliberately intended to alter minimally all the variables. Finally, it should
also be stressed that inadequate assumptions or biases can always lead to correct
conclusions, that is why the scientific approach usually evaluates a hypothesis or a
model, not so much through the lens of biases, but rather by using its quality of
predictions on new data [Pearl, 2000]. It is also for those reasons that a machine
learning based perspective is defended here. This is of course our own research bias
[Meyer, 2008]. Although epidemiologists would have rather used more classical
tools of their field, we would like to emphasize that we do not attempt to provide
any hypothesis in this paper, we are merely trying to favor one of the conflicting
hypothesis stated above with as much neutrality as possible. We also deem that
both, the data and the analysis provided here are valuable for epidemiologists to
pursue more advanced modeling strategies should they enquire it.
Now that our disclaimer has been clearly stated, let us start our analysis with
a few classical machine-learning definitions of variable relevance. Three degrees of
relevance are defined in [Kohavi and John, 1997]:
Definition 1. Let Ybe a target variable to predict, Xbe a set of input variables,
and Xjbe the same set without the jth variable: X\{Xj}:
AvariableXjis said “strongly relevant” in Xiffthere exists some xj,y and xj
for which p(x)>0,suchthat
p(y|x)6=p(y|xj)
AvariableXjis said “weakly relevant” iffit is not strongly relevant, but there
exists a subset XSof variables of Xjfor which there exists some xj,y and xS
with p(xj,x
S)>0such that
p(y|xj,x
S)6=p(y|xS)
Avariableissaidirrelevantiffitisnotrelevant(weaklyorstrongly).
In other words, an input variable Xjis strongly relevant if the removal of Xj
alone will result in a change of the conditional probability distribution of Y.An
input variable is weakly relevant if it is not strongly relevant, but in some context
XSit may change the conditional probability distribution of Y.
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 5
Strong relevance can be associated to the notion of causality because under the
causal sufficiency assumption (i.e. all the causes of an effect-variable are also present
in that dataset [Neapolitan, 2003]) then strong relevance implies direct causality.
This results from the fact that being unable to cancel the dependency between two
variables in a dataset (containing causal variables) can only b e explained by having
one of them be the most direct cause of the other [Neapolitan, 2003, Pearl, 2000].
Weak rele vance is more difficult to int e r p r e t b e c a u s e i t m e a n s t h a t i n s o m e c ontext
the variable improves prediction but not in others. This typically happen either with
redundant variables or with a variable that is not the most direct causal explanation
of the other. Irrelevance appears to be the easiest definition to interpret but unfortu-
nately it also requires the causal sufficiency assumption to be assuredly meaningful.
Indeed it can be shown that missing a strongly relevant variable can turn another
strongly relevant variable into an irrelevant one. In fact, that is the underlying
principle behind cryptography: the coded message (strongly relevant variable) is
irrelevant to the decoded message (target variable) unless you have the private key
(the other strongly relevant variable). As a result, we face two major problems when
modeling a) we do not have the real probabilities underlying our model but only
some data that allow us to estimate those and b) the causal sufficiency assumption
is a very strong hypothesis. For the former issue, machine-learning algorithms have
a long track record of estimating quite well underlying probabilities without having
recourse to too strong hypothesis [Mitchell, 1997, Hastie et al., 2001]. The latter
issue, i.e. the causal sufficiency assumption, explains why Science always attempts
to provide the explanation that lead to the most accurate predictions and admit it
as true until a better explanation can replace the previous one [Pearl, 2000]. Indeed
one can never be completely sure to have all the causal variables in the dataset.
Let us now look at the “a priori” causal network of our data in order to grasp
the extent of our causal (in)sufficiency (see Fig. 3.1). Simply stated, our variable
COVID-19-death-rate depends on the number of COVID-19-positive-cases in the
population (i.e. represented by our variable CaseRate). However, the CaseRate
variable is likely alt ere d by t he vac cin ati on in two positive ways (represented here
by green arrows) 1) vaccination should protect from deaths related to the virus 2)
vaccination may reduce the transmission. On the other side COVID-19 vaccines
may increase, via some spike-protein toxicity for example, a hidden variable called
here vaccines-death-rate. The excess mortality of the current year can thus be
predicted with four impacting variables: the COVID-19, the related vaccines, the
government measures and all the usual/cyclic causes of deaths. The latter is a
hidden variable (i.e. yellow in the figure) that is observable indirectly through
the all-cause excess deaths of the previous years. It is worth noting that the excess
mortality of the year before (i.e. 2020) is a bit more complex to handle because that
year already dealt with COVID-19 while also being subject to political measures
meant to reduce viral transmission, such as lockdowns, but yet without vaccines
(at least not before the week 46 used in our dataset).
3.1. Correlation Analysis. Some methods infer graphical models using only cor-
relations [Whittaker, 1990, Meyer et al., 2007]. Although there are well-known dan-
gers to connect pairwise correlations with causality, correlations can at least offer us
with two valuable information: 1) a ranking of variables by pairwise relevance and
2) the directionality of the pairwise relevance (correlated vs anti-correlated). For
those reasons, we report correlations for all the connecting paths of our graphical
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 6
Figure 3.1. Aprioricausalnetworkunderlyingourextracted
dataset. The main variables of our dataset are in blue. Hidden
variables are in yellow. Arrows of interest are in green and red.
Correlation Zscores Excess mortality 2021 with CovDeathR with
2019 2020 DoseR CaseR CovDthR DoseR CaseR
0-14 0.132 0.407 0.159 0.011 -0.092 -0.160 0.546
15-44 0.296 0.292 0.051 0.214 0.424 -0.320 0.546
45-64 0.360 0.234 -0.011 0.402 0.720 -0.179 0.546
Table 1. Pairwise correlations computed along all the paths of our
graphical model. Those correlations are computed on 234 samples
(18 countries times 13 4-weeks-periods).
model in the Table 1. It is worth noting that using Spearman’s correlation instead
of Pearson’s do not change neither the ranking of variables nor the directionality
of our pairwise dependencies.
At first glance, several values appear interesting. First we observe that 2020
has a better correlation than 2019 for the young probably because the impact of
lockdowns has been stronger for them than for the other age categories. Second
the CaseRate and the CovDeathRate (columns 4 and 5) which are constant for
all age-groups reflect the fatality rate of the disease for each age-group, that is no
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 7
impact on the 0 to 14, a small impact on the 15 to 44 and a stronger one on the 45-
64. The correlation between CaseRate and CovDeathRate is constant and strong as
expected. The DoseRate has a negative correlation with the CovDeathRate which is
to be expected since vaccines are meant to protect from COVID-19-death (at least
on the span of our 4-weeks period). Finally, the variable DoseRate has a strong
correlation with the current excess mortality for the younger ones while almost
no correlation for the two other age groups. Although it would be tempting to
conclude that COVID-19 vaccines have no beneficial effects on the older groups and
adeleteriousoneontheyoungerone,severalelementscanexplainthosecorrelations.
First, there are many very low-values both in the DoseRateandintheexcess
mortality for the younger group, hence a spurious value can appear there. Second,
the excess mortality is a variable that is affected by many other variables as shown
in our graphical model. Hence, those relations should be investigated more deeply
as we are doing in the next section.
3.2. Strong Relevance Analysis. In order to check for strongly relevant variables
(i.e. causal relationships) we make use of two different models (with their default pa-
rameters): the generalized linear model and the random forest. The first one makes
an assumption of linearity of relationships between variables and the other one is
known to capture a vast set of non-linear dependencies [Hastie et al., 2001]. The
loss function used for the random forest is the out-of-bag mean-squared-error (MSE)
whereas for the glm the Akaike criterion (AIC) is used [Sakamoto and Kitagawa, 1987,
Devroye et al., 1996, Breiman, 2001], both are computed internally by their respec-
tive R functions. Indeed the statistical language R, has been used both in the
extraction of the data and in the statistical analysis [Gentleman and Ihaka, 1996].
To assess which variables is strongly relevant, we make use of a unilateral paired
Wilcoxon Rank statistical test [Diettrich, 1998]. In other words, each variable that,
when removed from our full initial model, increases statistically significantly the
prediction error across the 2 models times 3 age-groups, is considered as strongly
relevant. The other variables are not impacting our models enough when removed.
As a result, those are considered weakly relevant. The p-values are not corrected
here simply because each variable is evaluated independently of the others. In other
words, those are only in competition with the full model but not with the other
variables. It differs from a strategy that aims to select the best among competitive
ones where an adjustment would be advised.
The three strongly relevant variables identified here already deliver a mini-
mal model with quite accurate prediction. Indeed, the second column named
“20+CDR+CR” standing for the three strongly relevant variables, namely Zscores-
Past1Y, CovDeathRate, CaseRate in the Table 3, shows that removing the two
weakly relevant variables together do not impact significantly our prediction errors
(in fact column 2 of Table 3 has similar errors than column 2 of Table 2). The fact
that DoseRate is a strongly relevant variable can only be explained in our graphical
model through the red arrow. In order to better quantify this negative impact of
vaccines we can further our analysis by replacing DoseRate by CaseRate in that
minimal model. Indeed, this should results in an increase in errors because the
CaseRate information should already be captured by the CovDeathRate variable.
Since machine learning algorithms can sometimes be highly sensitive to the number
of variables [Meyer, 2008], replacing one rate (i.e. DoseRate)byanotherofsimilar
structure (i.e. CaseRate) allows us to eliminate a potential bias. The columns 2
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 8
Error with All vars -2019 -2020 -CovDthR -CaseR -DoseR
AIC-0-14 408.883 407.974 452.099 413.976 408.304 411.159
MSE-0-14 0.331 0.337 0.383 0.328 0.341 0.330
AIC-15-44 564.756 570.051 575.865 595.423 562.756 576.098
MSE-15-44 0.697 0.708 0.766 0.772 0.700 0.737
AIC-45-64 715.590 719.995 731.761 824.469 714.575 723.814
MSE-45-64 1.436 1.567 1.585 1.860 1.546 1.546
p-values ref 0.109 0.016 0.031 0.844 0.031
Relevance -Weak Strong Strong Weak Strong
Table 2 . Strong-relevance evaluated with an unilateral paired
Wilcox Rank test on the Akaike criterion of generalized linear mod-
els (AIC) and the out-of-bag mean-square-error of a random forests
(MSE). In bold are the values bigger than their corresponding ref-
erence of the first column.
Error with All vars 20+CDR+DR 20+CDR+CR 20+DR 20+CR
AIC-0-14 408.88 407.44 410.32 410.86 417.98
MSE-0-14 0.33 0.35 0.35 0.35 0.35
AIC-15-44 564.76 568.05 580.48 617.78 610.56
MSE-15-44 0.70 0.71 0.75 0.90 0.81
AIC-45-64 715.59 718.15 726.48 900.61 861.69
MSE-45-64 1.44 1.52 1.66 2.75 2.38
Conclusion - close from ref CR is worse bad model CR is better
Table 3 . Errors showing the inversion of relevance between
CaseRate (CR) and DoseRate (DR) in function of CovDeathRate
(CDR), i.e. present (col. 2 and 3) and absent (col. 4 and 5)
and 3 of Table 3 show the results of this strategy. Another way to check if our
network makes sense, is to recompute the previous columns (i.e. CaseRate instead
of DoseRate) but this time with the variable CovDeathRate removed. This strategy
should allow us to observe if the CaseRate becomes then more relevant than the
DoseRate. Indeed, since the CovDeathRate is preventing the flow of information
from the CaseRate variable toward the 2021 excess mor tal ity vari abl e, it is expected
that once removed, the effect of the disease will become more relevant than the ef-
fect of the vaccines (in order to predict excess mortality). The next two columns
(i.e. 5 and 6) of the Table 3 show precisely the inversion of relevance of those two
variables, thereby further reinforcing the validity of our graphical mode l.
However, we can already note that the first age-category (i.e. 0-14) seems quite
unaffected by the removal of the CovDeathRate variable and it is quite explain abl e
due to the very low amount of deaths in that age-category. On the other side,
the age-category 45-64 is strongly impacted by the removal of the CovDeathRate
variable. Indeed, in that age-category the relevance inversion is much stronger.
To make that effect more visible, we can report the ratio of error measures when
we replace CaseRate by DoseRate and reciprocally. In the Table 4, we report the
ratio between the model using the most impactful variable (either CaseRate or
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 9
Error 20+CDR 20 19+CDR 19 19+20+CDR 19+20
ratios +CR/+DR +DR/+CR +CR/+DR +DR/+CR +CR/+DR +DR/+CR
AIC-0-14 1.01 0.98 1.01 0.99 1.01 0.98
MSE-0-14 1.00 1.01 0.97 1.04 0.98 1.06
AIC-15-44 1.02 1.01 1.02 1.01 1.02 1.01
MSE-15-44 1.06 1.11 1.12 1.06 1.05 1.02
AIC-45-64 1.01 1.05 1.01 1.05 1.01 1.05
MSE-45-64 1.09 1.16 1.14 1.20 0.98 1.19
Table 4 . Error ratios of models that measure the impact of
DoseRate (DR) versus the impact of CaseRate (CR). In bold the
results supporting that the variable CaseRate is more impactful
than the variable DoseRate.ResultsfavorCaseRate only in the
older category.
DoseRate depending on the presence of CovDeathRate )overthemodelusingthe
other variable. We also report the same values when our models uses the excess
mortality of 2019 rather than of 2020 and also with both years jointly.
We observe t h a t DoseRate and CaseRate variables appear equally impactful in
the 0-14 category independently of the presence of CovDeathRate. Indeed, not
only all the ratio are close to one, thereby showing that both variables have similar
impact on predictions but also the best model is not always using the same variable,
i.e. DoseRate is slightly more impactful when using linear models and CaseRate
when using random forests. In the 15-44 years, we observe also close-to-one ratios
at least with linear models. There is a stronger unbalance with random forests.
However, the unbalance is again not always in favor of the same variable. In
fact, the negative impact of DoseRate seem equal or even slightly stronger than
the negative impact of CaseRate. It is only in the last age-category, i.e. 45-64,
that a clear message is conveyed. In the latter case, the CaseRate variable (in
absence of CovDeathRate)ismoreimpactfulthantheDoseRate (in presence of
CovDeathRate). It should be emphasized that our models do not, as is, evaluate
those impacts in absolute number of deaths because we are predicting z-scores on
excess all-cause mortality. This is also the reason why the whole strategy defended
in this paper has been focused on comparing impacts on predictions rather than
quantifying them in absolute terms. We deem this approach as more crude but
also more reliable since it does not require any transformation of the downloaded
variables. As a consequence, i t is qu ite wor rying that two age categories have
excess mortality similarly impacted by the negative effects of vaccines than they
are impacted by the disease. However, those age categories were known to have a
low fatality rate initially [Semenzato et al., 2021].
4. CONCLUSION
Our goal in this study has been to favor one of the conflicting hypothesis stated in
the introduction: either the COVID-19 vaccines increase the all-cause mortality in
the same proportion than they protect, in each age-category [Neil and Fenton, 2021,
Crawford, 2021] or it does not increase the non-COVID-19 mortality at all [Xu et al., 2021].
We prov i d e d a g r aphical mo d e l a n d s t u d i e d t he releva n c e o f s e veral ke y variables
THE IMPACT OF COVID-19 VACCINES ON ALL-CAUSE MORTALITY IN EU IN 2021 10
in order to achieve our goal. Interestingly our results, based on EU data, agree
with [Neil and Fenton, 2021, Crawford, 2021] for the 0-44 years, that is vaccines
have clearly no net benefits on excess mortality. The fact that the vaccines have
been delivered to an important proportion of the population means that even a
small toxicity could be responsible for as many deaths than the disease itself. In-
deed not everyone contract the virus and additionally in those that contract the
virus, very few dies in the youngest categories [Semenzato et al., 2021]. However,
our third category shows a different signal. It would be tempting to conclude that
the benefit-risk balance for the oldest category is favorable, but the fact that the
mortality is better explained by the variable CaseRate than the variable DoseR-
ate does not really allow to assess vaccines efficacies. In other words, we have not
tried to compare benefits of vaccines versus costs of vaccines as implicitly done in
[Neil and Fenton, 2021, Crawford, 2021], we have rather compared costs of vaccines
versus costs of the disease. As a consequence, our results do not necessarily op-
pose those results even for the third age-group. However, our results disagree with
[Xu et al., 2021] for the 0-44 years old. We believe that the flu-vaccine induced
bias mentioned above could explain the different conclusions reached. Beside, for
all studies mentioned we cannot put aside all the possible multiple confounding
variables impacting at least parti all y the s tat ist ics l ike diff ere nt u nde rly ing p o pu-
lations, healths and healthcare systems, type of vaccines used, delays applied in
between doses,... Nonetheless, the excess mortality of 2021 in EU is well above the
excess mortality of 2020 that is itself well above 2019. It appears that the variable
COVID-19-Death-Rate is not sufficient to explain the surge in 2021. Our variable
DoseRate, related to COVID-19 vaccines, apparently explains a major part of the
signal observed in the 0-44 years category. As a consequence, until a better predic-
tive variable is found, our results clearly suggest that the benefit-risk balance for
the 0-44 years old is not in favor of those COVID-19 vaccines. This could change in
the future, for example with the emergence of less favorable variants or equivalently
with more favorable COVID-19 vaccines.
Acknowledgments: I would like to thank several colleagues (who will recognize
themselves) for their helpful comments on this work. I hope that those who have
expressed concern with the possible political use of our conclusion will understand
that we are dealing here with life and death matters (literally). In those situation,
we should all agree that scientists must rapidly provide as many tools as possible
to analyze a perilous situation.
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