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. 2023 Jul 29:6:100416.
doi: 10.1016/j.puhip.2023.100416. eCollection 2023 Dec.

Patterns of protection, infection, and detection: Country-level effectiveness of COVID-19 vaccination in reducing mortality worldwide

C Rughiniș  1 , M Dima  2 , S-N Vulpe  3 , R Rughiniș  4 , S Vasile  3
Affiliations

Patterns of protection, infection, and detection: Country-level effectiveness of COVID-19 vaccination in reducing mortality worldwide

C Rughiniș et al. Public Health Pract (Oxf). .

Abstract

Background: The relationship between COVID-19 vaccination and mortality has been established through clinical trials and other investigations at the individual level. In this study, we aimed to investigate the negative relationship between mortality and COVID-19 vaccination at country level.

Study design: We conducted an exploratory, correlational, country-level analysis of open data centralized by Our World in Data concerning the cumulative COVID-19 mortality for the winter wave (October 2021-March 2022) of the pandemic as function of the vaccination rate in October 2021.

Methods: We controlled variables that capture country-level social development and level of testing. We also deployed three segmentation tactics, distinguishing among countries based on their level of COVID-19 testing, age structure, and types of vaccines used.

Results: Controlling for confounding factors did not highlight a statistically significant relationship between vaccination and cumulative mortality in the total country sample. Still, a strong, significant, negative relationship between cumulative mortality (log scale) and vaccination was highlighted through segmentation analysis for countries positioned at the higher end of the social development spectrum. The strongest estimate for vaccine effectiveness at ecological level was obtained for the set of countries that used Western-only vaccines.

Conclusions: COVID-19 testing (log scale) has a significant and positive relationship with cumulative mortality for all subsamples, consistent with patterns of under- and overreporting of COVID-19 deaths at country level, partly driven by testing. This indicates that testing intensity should be controlled as a potential confounder in future ecological analyses of COVID-19 mortality.

Keywords: COVID-19 testing; COVID-19 vaccine; Ecological study; Mortality; Vaccine effectiveness.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Exploration of covariation patterns between COVID-19 cumulative mortality and both the vaccination rate and the HDI.
Fig. 2
Fig. 2
Exploration of covariation patterns between COVID-19 cumulative mortality and the testing rate, the proportion of people aged 65 and older, GNI per capita, and mean years of schooling with linear vs. logarithmic scaling for all countries.
Fig. 3
Fig. 3
Exploring patterns of covariation between cumulative mortality and vaccination rate in three segmentation scenarios: volume of testing, age structure, and vaccine type.
See this image and copyright information in PMC

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