Change in age distribution of COVID-19 deaths with the introduction of COVID-19 vaccination

Roberta Pastorino; Angelo Maria Pezzullo; Leonardo Villani; Francesco Andrea Causio; Cathrine Axfors; Despina G Contopoulos-Ioannidis; Stefania Boccia; John P A Ioannidis

doi:10.1016/j.envres.2021.112342

Change in age distribution of COVID-19 deaths with the introduction of COVID-19 vaccination

Environ Res. 2022 Mar;204(Pt C):112342. doi: 10.1016/j.envres.2021.112342. Epub 2021 Nov 5.

Authors

Roberta Pastorino¹, Angelo Maria Pezzullo², Leonardo Villani², Francesco Andrea Causio², Cathrine Axfors³, Despina G Contopoulos-Ioannidis⁴, Stefania Boccia⁵, John P A Ioannidis⁶

Affiliations

¹ Department of Woman and Child Health and Public Health - Public Health Area, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.
² Section of Hygiene, University Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy.
³ Meta-Research Innovation Center at Stanford (METRICS), Stanford University, Stanford, CA, USA.
⁴ Division of Infectious Diseases, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
⁵ Department of Woman and Child Health and Public Health - Public Health Area, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; Section of Hygiene, University Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy.
⁶ Meta-Research Innovation Center at Stanford (METRICS), Stanford University, Stanford, CA, USA; Department of Medicine, of Epidemiology and Population Health, of Biomedical Data Science, and of Statistics, Stanford University, Stanford, CA, USA. Electronic address: jioannid@stanford.edu.

Abstract

Objectives: Most countries initially deployed COVID-19 vaccines preferentially in elderly populations. We aimed to evaluate whether population-level vaccine effectiveness is heralded by an increase in the relative proportion of deaths among non-elderly populations that were less covered by vaccination programs.

Eligible data: We collected data from 40 countries on age-stratified COVID-19 deaths during the vaccination period (1/14/2021-5/31/2021) and two control periods (entire pre-vaccination period and excluding the first wave).

Main outcome measures: We meta-analyzed the proportion of deaths in different age groups in vaccination versus control periods in (1) countries with low vaccination rates; (2) countries with age-independent vaccination policies; and (3) countries with standard age-dependent vaccination policies.

Results: Countries that prioritized vaccination among older people saw an increasing share of deaths among 0-69 year old people in the vaccination versus the two control periods (summary proportion ratio 1.32 [95 CI% 1.24-1.41] and 1.35 [95 CI% 1.26-1.44)]. No such change was seen on average in countries with age-independent vaccination policies (1.05 [95 CI% 0.78-1.41 and 0.97 [95 CI% 0.95-1.00], respectively) and limited vaccination (0.93 [95 CI% 0.85-1.01] and 0.95 [95 CI% 0.87-1.03], respectively). Proportion ratios were associated with the difference of vaccination rates in elderly versus non-elderly people. No significant changes occurred in the share of deaths in age 0-49 among all 0-69 deaths in the vaccination versus pre-vaccination periods.

Conclusions: The substantial shift in the age distribution of COVID-19 deaths in countries that rapidly implemented vaccination predominantly among elderly provides evidence for the population level-effectiveness of COVID-19 vaccination and a favorable evolution of the pandemic towards endemicity with fewer elderly deaths.

Keywords: COVID-19; Death; Population data; Vaccination.

MeSH terms

Adolescent
Adult
Age Distribution
Aged
COVID-19 Vaccines*
COVID-19*
Child
Child, Preschool
Humans
Infant
Infant, Newborn
Middle Aged
SARS-CoV-2
Vaccination
Vaccine Efficacy
Young Adult

Substances

COVID-19 Vaccines