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How many years did unvaccinated people lose during the COVID-19 pandemic?

During the COVID-19 pandemic, many of us could finally feel relief when the first approved vaccines saw the light of day. But it didn't take long for a segment of the population to turn against vaccination, preferring to be unprotected from the virus. That vaccines are effective in fighting disease has long been proven by many studies. Even at the Faculty of Science of Charles University, one such study was recently conducted. The data studied by Dr. Klára Hulíková Tesárková and her colleague Prof. Dagmar Dzúrová, who is, among others, the supervisor of the Master's degree in Social Epidemiology at the Department of Social Geography and Regional Development supported by the NPO-SYRI* project. So how does a study that has newly analyzed the data from the coronavirus era speak?

During the pandemic years, the Czech Republic ranked among the worst countries in the world in terms of COVID-19-related deaths (currently 41,000) per capita (10.5 million). This is a shockingly high number compared to its neighboring, similarly populated country - Austria. COVID-19-related deaths there record barely half. Misinformation and hesitancy in vaccination, leading to vaccine refusal or delayed vaccination, are thought to be key factors in the high number of pandemic deaths in the Czech Republic. The number of patients who have died with completed vaccination is also often in the public eye. This, of course, happens regarding the vaccination rate. The vaccine has never guaranteed 100% protection from infection. But the results of the new study will help us understand how much vaccination contributes to saving lives.

In the study, the researchers worked with a commonly used demographic method that considers premature deaths, such as years of life lost (YLL) and years of life saved (YLS) due to vaccination. Of particular importance to the study's conclusion was the observed difference in YLL and YLS between COVID-19 victims with or without completed vaccination. Individual data from a database on all COVID-19-related deaths in the Czech Republic from age 12 years and up were used in the analysis. In evaluating the effectiveness of vaccines, the reduction in the risk of hospitalization and death was included.

Below is a sample of the official data used in the study. In the period analyzed, 5797 deaths were reported in the Czech Republic, of which 3441 were in the population without complete vaccination (59.4% of the total). In terms of age, the highest number of deaths occurred in the 65-84 age group (3570), followed by the oldest age group 85 years and older (1481). In terms of vaccination, the distribution of deaths was different. The highest proportion of deaths without completed vaccination was in the lowest age group (86.9% of the 61 deaths registered in the 12-44 age group). In the age group 45-64 years, 549 persons (80.1%) died without having completed vaccination, and 136 persons (19.9%) with completed vaccination.

Until the 1st of October 2021, approximately 64% of the Czech population aged 12 years and over had been vaccinated. The highest coverage of completed vaccination was in the oldest age groups - approximately 83.5% in the 85+ age group and approximately 85.0% in the 65-84 age group. Only 70.1% of the population aged 45-64 years had completed vaccination coverage and 49.5% in the youngest age group (12-44 years). Thus, the population with completed vaccination had a significantly lower COVID-19 mortality rate (on average 7.5 times lower).

Graphs illustrating the number of victims across age categories with and without completed vaccination for men (left) and women (right).
Source: Study


The baseline dataset used for the analysis included records of individual COVID-19-related deaths during the three-month period from 1st October to 31st December 2021. The study period was chosen because the dominant strain at that time was only the Delta variant. So what were the results of the study?

The conclusions of the research show that the risk of COVID-19-related deaths increases significantly with age, but the rate is higher in the population without completed vaccination. If we exclude the youngest age group, where the numbers of deaths are low, the risk of death for the population without completed vaccination aged 85 years and over is 6.4 times higher compared to the population with completed vaccination for the same age group. The risk is 7.3 times higher in the 65-84 age group and even 9.5 times higher for the subpopulation without completed vaccination in the 45-64 age group.

This result clearly illustrates that vaccination is effective in saving lives, even crucial during a pandemic. Moreover, in the case of the Czech Republic, among the population with completed vaccination, almost 15,000 COVID-19-related deaths were potentially prevented over the three-month analysis period. Vaccination helped to reduce YLL among the fully vaccinated by approximately 88% during the period under review, and the registered number of deaths across all age categories is approximately 3.5 times lower than would have been expected without vaccination. This study demonstrates that vaccination against COVID-19 saves lives and saves years of potential future lives. The assessment of years of life lost is a good indicator of the impact of a pandemic because it provides a more relevant perspective than raw mortality rates (numbers of deaths per population). Unfortunately, this figure is not often used in practice. In this study, the YLL rate was used not only to illustrate pandemic outcomes but more importantly to assess the effect of completed vaccination and again provide clear evidence of the benefit of COVID-19 vaccination.

Hulíková Tesárková, K., Dzúrová, D. COVID-19: years of life lost (YLL) and saved (YLS) as an expression of the role of vaccination. Sci Rep 12, 18129 (2022).

Tereza Žirovnická

*NPO-SYRI - „Národní institut pro výzkum socioekonomických dopadů nemocí a systémových rizik,“ č. LX22NPO5101, financovaný Next Generation EU (=National Institute for Research on the Socioeconomic Impact of Diseases and Systemic Risks," No. LX22NPO5101, funded by Next Generation EU)

Published: Mar 29, 2023 07:45 PM

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