Young adult mortality in Israel during the COVID-19 crisis

In this paper, we analyze excess mortality in Israel during the COVID-19 crisis, focusing on the age group of young adults under 50 years of age, as their susceptibility to COVID-19 mortality is low. Based primarily on online data from the Central Bureau of Statistics of Israel, we observed an unexpected rise of excess mortality among 20 to 49-year-olds in February-March 2021. It should be noted that excess mortality peaks among these young age groups are rarely observed, with low number of deaths that are usually caused by wars. We examined whether COVID-19 could account for this excess mortality. The inconsistency between the reported COVID-19 deaths and the excess deaths within this age group led to consider other potential causes: accident and vaccination. Indeed, the surge in mortality coincided with the rollout of the Israeli vaccination campaign for the 20 sto 49-year-olds, which reached more than 75% of individuals in this age group. This unexpected rise in excess mortality among young adults was also found in two other countries, the United Kingdom and Hungary, which have in common with Israel a massive vaccination of their populations. Thus, our observations should prompt to pause the campaign, while clarifying the underlying reasons for those excess deaths, especially in the context of a low mortality risk from COVID-19 within adults under 50 years of age.


Introduction
Widely-cited studies have concluded to the efficiency of the Pfizer Comirnaty injections to prevent COVID-19 infections, hospitalizations and deaths in Israel (see [1] and [2]).Excess mortality by ethnic group, city and age in Israel from March to November 2020 was previously reported [3].However, to the best of our knowledge, no study analyzed the mortality in the young adult population in Israel after the start of the Israeli vaccination campaign in December 2020.
Overall mortality data (both COVID and non-COVID related) have several advantages over COVID-19 mortality data for analyzing the impact of vaccination, since (i) they are less susceptible to bias or manipulation than "COVID-19 deaths," which may vary in definition and practical calculation depending on the context, and (ii) they capture possible "collateral effects" of vaccination beyond COVID-19 deaths, such as its possible impact on youth mortality.The goal of this paper is to analyze excess mortality in Israel in 2020-2021, focusing on those adult age groups that are less susceptible to COVID19 mortality: the group of the 20 to 49-year-olds.

Status of excess mortality in 20-49 age groups
We focused on the mortality of adults under the age of 50 in Israel in 2020-2021 for it is a subject of limited documentation.Focusing on the 20-49 age group limits the confounding effect of COVID-19 mortality and avoids the bias due to the "harvesting" effect of premature deaths in 2020 of individuals with poor health condition, whose health status deteriorated because of both lockdowns and COVID-19.Of note, mortality is seasonal in nature, hence should be adjusted for systematic patterns within the year.
Moreover, mortality must be related to the population in order to be compared from year to year (when the population increases, the number of deaths also increases).The number of deaths relative to the population defines the population-adjusted "mortality rate".In some age groups, the mortality rate shows a trend over time, which may reflect -for example-medical advances and improvements in the health status of the population.Excess mortality is therefore studied as the deviation of the mortality rate from that expected from long-term drift and seasonal patterns.
Excess mortality in Israel was calculated on a monthly basis, as shown in Figure 1.The excess mortality was assessed as the difference between the monthly observed mortality rate and the expected mortality rate calculated from a linear model including a long-term linear drift and monthly seasonal dummies.
Unusual events of national interest (including wars) were reported.The deaths that occurred on the day of a dramatic accident, which took place in Meron on April 30, 2021, were carefully taken into consideration to avoid any bias, and data was plotted with and without this event.Because the cause is accidental, deaths from the Meron tragedy were systematically discarded from the rest of this paper.Compared to previous mortality peaks, the peaks between February to April 2021 occurred in all three age groups and lasted two months in a row in the 20-39 age groups.This led us to aggregate excess mortality rates with respect to both the time and age dimensions (Figure 2).
We plotted the three-month moving average of the 20 to 49-year-olds excess mortality rates, as shown in the lower panel of  graph.

Assessing the potential causes of excess mortality
We focused on COVID-19 as a potential underlying cause of such excess mortality.In Figure 3

Comparison with other countries
We chose to compare the mortality growth of young adult population in countries with varying policies of vaccination.As a comparison, we compiled the mortality rate variation from Jan-May 2020 to Jan-May 2021 in the various age groups in 25 European countries as well as in Israel, as shown in the Appendix in Table A1.The average mortality growth in percentage for each age group was further calculated in mass and moderate vaccination countries (Appendix, Table A2).The p-value of a one-sided (equal variance) t-test was assessed and showed that the two averages were significantly different (Table A2).This table was subsequently presented as a histogram (Figure 4).From this figure and our calculation, it appears that the difference between mass and moderate vaccination is significant in terms of mortality growth in young age groups, and that mass vaccination is associated to a higher young adults' mortality growth.This observation lends further support to suggest a link between vaccination and youth mortality in Israel, and in those countries that perform mass vaccination.

Figure 1 :
Figure 1: Monthly excess mortality rates in Israel from January 2011 to May 2021.Mortality rates are expressed in number of monthly deaths per 100,000 inhabitants.A graph was plotted per each age group

Figure 2 .
Intriguingly in 2021, the values in March (average of the January-February and March excess mortality rates) and in April (average of the February-March-April excess mortality rates) exhibited the same magnitude as the peak during the Israeli ground offensive in Gaza in July 2014, as part of Operation Protective Edge, where 67 Israeli soldiers lost their lives.

Figure 2 :
Figure 2: Upper panel: Mortality rate in the age group of the 20-49-year-olds (weighted average of the 20-29, 30-39 and 40-49-year-olds mortality rates).The excess mortality rates are defined as the mortality rates exceeding a long-term drift and seasonal effects, calibrated by a linear model with a linear trend and monthly dummy variables.All data are shown without the deaths from the Meron tragedy (April 30, 2021).Red lines indicate the main unusual national events: in July 2014, the ground offensive of the Operation Protective Edge and in January 2021, the start of the vaccination campaign for these age categories.Lower panel: Graph was obtained from a three-month moving average on the time series plotted in the upper , we compiled the official COVID deaths with the excess deaths, assessed by the above excess mortality rates both in the age groups below and above 50 years old.As expected, the rise in the excess mortality was parallel to the rise of COVID-19 deaths both in October 2020 and in January 2021.However, an inconsistency arises between the official COVID-19 deaths and excess deaths below 50 years of age starting in February 2021.Moreover, Figure3casts new lights on unreported rises in the young adult mortality that cannot be explained by the overall trend of COVID-19 deaths.While three mortality peaks occur respectively in June 2020, October 2020, and in February-March 2021, only the one in October 2020 coincides with an increase in COVID-19 deaths.Since this peak corresponds to the lowest rise in deaths, and the two other increases cannot be explained by the overall trend of COVID-19 deaths, the need to understand the reason for the last peak (the one with the highest magnitude) appears all the more critical.The only unprecedented noticeable event in this timeframe was the beginning of the vaccination campaign in Israel, which took place in January 2021 for this age group.We thus calculated the proportion of vaccinated young adults as documented in Table1from January to May 2021, and observed that February and March 2021 happen to be the two months with the highest number of second doses administered among the injection months (28% of the 20-49 age group having received their second dose in each of these two months).Thus, from the data put altogether, the only event that can plausibly account for the repeated highest rises in excess deaths both in February and March 2021 is the vaccination.

Figure 3 : 1 :
Figure 3: Monthly official (all ages) COVID deaths (left axis) and excess deaths for the 20-49-year-olds (right axis) and the above 50-year-olds (left axis).The excess deaths are computed from the excess mortality rates presented above (retaining only positive values).Source for official COVID deaths: Israeli

Figure 4 :
Figure 4: Mortality growth in % from Jan-May 2020 to Jan-May 2021 in Israel, England & Wales, Hungary and 23 other European countries which have more moderately vaccinated their populations, for ages 20-29, 30-39 and 40-49.Sources: CBS, Eurostat, ONS.See Table A1 in the Appendix for source data.