Country differences in transmissibility, age distribution and case-fatality of SARS-CoV-2: a global ecological analysis
File(s)
Published version
Author(s)
Favas, Caroline
Jarrett, Prudence
Ratnayake, Ruwan
Watson, Oliver J
Checchi, Francesco
Type
Journal Article
Abstract
Objectives The first COVID-19 pandemic waves in many low-income countries appeared milder than initially forecasted. We conducted a country-level ecological study to describe patterns in key SARS-CoV-2 outcomes by country and region and explore associations with potential explanatory factors, including population age structure and prior exposure to endemic parasitic infections.
Methods We collected publicly available data and compared them using standardisation techniques. We then explored the association between exposures and outcomes using random forest and linear regression. We adjusted for potential confounders and plausible effect modifications.
Results While mean time-varying reproduction number was highest in the European and Americas regions, median age of death was lower in the Africa region, with a broadly similar case-fatality ratio. Population age was strongly associated with mean (β=0.01, 95% CI, 0.005, 0.011) and median age of cases (β=-0.40, 95% CI, -0.53, -0.26) and deaths (β= 0.40, 95% CI, 0.17, 0.62).
Conclusions Population age seems an important country-level factor explaining both transmissibility and age distribution of observed cases and deaths. Endemic infections seem unlikely, from this analysis, to be key drivers of the variation in observed epidemic trends. Our study was limited by the availability of outcome data and its causally uncertain ecological design.
Methods We collected publicly available data and compared them using standardisation techniques. We then explored the association between exposures and outcomes using random forest and linear regression. We adjusted for potential confounders and plausible effect modifications.
Results While mean time-varying reproduction number was highest in the European and Americas regions, median age of death was lower in the Africa region, with a broadly similar case-fatality ratio. Population age was strongly associated with mean (β=0.01, 95% CI, 0.005, 0.011) and median age of cases (β=-0.40, 95% CI, -0.53, -0.26) and deaths (β= 0.40, 95% CI, 0.17, 0.62).
Conclusions Population age seems an important country-level factor explaining both transmissibility and age distribution of observed cases and deaths. Endemic infections seem unlikely, from this analysis, to be key drivers of the variation in observed epidemic trends. Our study was limited by the availability of outcome data and its causally uncertain ecological design.
Date Issued
2022-01-01
Date Acceptance
2021-11-01
Citation
International Journal of Infectious Diseases, 2022, 114, pp.210-218
ISSN
1201-9712
Publisher
Elsevier
Start Page
210
End Page
218
Journal / Book Title
International Journal of Infectious Diseases
Volume
114
Copyright Statement
© 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/34749011
PII: S1201-9712(21)00850-X
Subjects
age structure
CHILDREN
Coronavirus
COVID-19
endemic infections
IMMUNITY
INFECTION
Infectious Diseases
Life Sciences & Biomedicine
parasites
Science & Technology
transmissibility
Publication Status
Published
Coverage Spatial
Canada
Date Publish Online
2021-11-06