National age and coresidence patterns shape COVID-19 vulnerability

Area of Science:

• Demography
• Epidemiology
• Public Health

Background:

• The coronavirus disease 2019 (COVID-19) pandemic highlighted the importance of population structure in disease transmission and mortality.
• Understanding how age distribution and household living arrangements influence vulnerability is crucial for effective public health interventions.

Purpose of the Study:

• To estimate the impact of age and coresidence patterns on national population vulnerability to COVID-19 outbreaks.
• To assess the effectiveness of targeted infection prevention strategies based on demographic and household characteristics.

Main Methods:

• Utilized harmonized census data from 81 countries to model population vulnerability.
• Simulated a 10% random infection rate within private households and analyzed subsequent within-household transmission.
• Evaluated the impact of preventing primary infections in different age groups on overall mortality.

Main Results:

• European and North American countries exhibit higher general COVID-19 mortality risk due to age structures.
• African and Asian countries face increased mortality risk from within-household COVID-19 transmission due to elderly coresidence patterns.
• Southern European countries are identified as most vulnerable due to combined factors of aging populations and intergenerational coresidence.

Conclusions:

• Population age structure and household composition are critical determinants of COVID-19 vulnerability.
• Targeted infection control strategies, such as protecting the elderly or younger age groups, should be tailored to country-specific demographic and household contexts.
• Interventions focused on preventing primary infections in the elderly are most effective in countries with small, non-intergenerational households, while confining younger populations is more impactful in countries with large, intergenerational households.