Volume 48 - Article 28 | Pages 829–848  

Age reporting for the oldest old in the Brazilian COVID-19 vaccination database: What can we learn from it?

By Cássio M. Turra, Fernando Fernandes, Júlia Almeida Calazans, Marília R. Nepomuceno


Background: Age misreporting affects population estimates at older ages. In Brazil, every citizen must be registered and show an identity document to vaccinate against COVID-19. This requirement to present proof of age provides a unique opportunity for measuring the oldest-old population using novel administrative data.

Objective: To offer critically assessed estimates of the Brazilian population aged 80 and older based on data from the vaccination registration system (VRS). To uncover discrepancies between the number of vaccinated oldest-old people and the projections used to estimate target populations for COVID-19 vaccination.

Methods: We calculate data quality indicators based on data from the VRS – namely, 100+/80+ and 90+/80+ population proportions, sex ratios, and the Myers blended index – and compare them to those based on data on target populations from Brazilian censuses and demographic projections, and from Sweden – a country with high-quality data. We also estimate vaccination coverage ratios using population projections adjusted to excess deaths as the denominators.

Results: Requiring documentation reduces age heaping, age exaggeration, and sex ratios marginally. However, it cannot solve the problem of the misreporting of birth dates due to the absence of long-standing birth registration systems in Brazil, particularly in the northern and central regions. In addition, we find a mismatch between the projected populations and numbers of vaccinated people across regions.

Conclusions: Despite improvements in data quality in Brazil, we are still not confident about the accuracy of age reporting among the oldest old in the less advantaged Brazilian regions. The postponement of the 2020 census reduced the ability of authorities to define the target populations for vaccinations against COVID-19 and other diseases.

Contribution: This is the first study to compare population estimates for the oldest old in administrative data and census data in Brazil. Age misreporting resulted in discrepancies that may have compromised the efficacy of the COVID-19 vaccination campaign.

Author's Affiliation

Other articles by the same author/authors in Demographic Research

World population aging as a function of period demographic conditions
Volume 48 - Article 13

Assessing the quality of education reporting in Brazilian censuses
Volume 42 - Article 15

Mortality selection among adults in Brazil: The survival advantage of Air Force officers
Volume 37 - Article 41

The number of centenarians in Brazil: Indirect estimates based on death certificates
Volume 20 - Article 20

Most recent similar articles in Demographic Research

Racial classification as a multistate process
Volume 50 - Article 17    | Keywords: Brazil, demography, increments to life, life expectancy, life table, mortality, multistate, race/ethnicity

Measuring short-term mobility patterns in North America using Facebook advertising data, with an application to adjusting COVID-19 mortality rates
Volume 50 - Article 10    | Keywords: COVID-19, data collection, Facebook, mortality, North America, short-term mobility

Immigrant mortality advantage in the United States during the first year of the COVID-19 pandemic
Volume 50 - Article 7    | Keywords: COVID-19, immigrants, mortality

Leaving and returning to the parental home during COVID times in France, Italy, Germany, Spain, and the United Kingdom
Volume 50 - Article 3    | Keywords: behavior, COVID-19, intentions, leaving the parental home, motivations

The COVID-19 pandemic and fertility responses: TFR simulation analysis using parity progressions in South Korea
Volume 49 - Article 32    | Keywords: COVID-19, fertility intentions, marriage intentions, simulation