Social Contact Patterns in Rural and Urban Settings, Mozambique, 2021-2022

Abstract

Few sources have reported empirical social contact data from resource-poor settings. To address this shortfall, we recruited 1,363 participants from rural and urban areas of Mozambique during the COVID-19 pandemic, determining age, sex, and relation to the contact for each person. Participants reported a mean of 8.3 (95% CI 8.0-8.6) contacts per person. The mean contact rates were higher in the rural site compared with the urban site (9.8 vs 6.8; p<0.01). Using mathematical models, we noted higher vaccine effects in the rural site when comparing empirical (32%) with synthetic (29%) contact matrices and lower corresponding vaccine effects in the urban site (32% vs 35%). Those effects were prominent in younger (0-9 years) and older (≥60 years) persons. Our work highlights the importance of empirical data, showing differences in contact rates and patterns between rural and urban sites in Mozambique and their nonnegligible effects in modeling potential effects of vaccine interventions.

Keywords: COVID-19; Mozambique; SARS-CoV-2; coronavirus disease; mathematical modeling; ocial contact patterns; rural populations; severe acute respiratory syndrome 2; vaccines; viruses.

Figure 5

Equation. Overall vaccine effect (VE) calculated as the percent reduction of cases in the presence versus absence of vaccine.

Figure 1

Distribution patterns of number of contacts in rural and urban areas in study of social contact patterns, Mozambique, 2022. A, B) Density distribution of the number of contacts per person in the rural (A) and urban (B) sites. Black vertical lines indicate means; 95% CIs are provided in parentheses. C) Boxplots of the distribution of number of contacts by site (gold, rural; aqua, urban). Horizontal lines within boxes indicate median number of contacts; top and bottom lines indicate interquartile ranges; error bars indicate 95% CIs.

Figure 2

Age-specific contact matrices for rural (A) and urban (B) sites from study of human contact patterns, Mozambique, 2022. Matrices depict the average mean number of persons in age group j (y-axes) with whom a participant in age group i (x-axes) came into contact.

Figure 3

Contact matrices based on empiric data from study of human contact patterns Mozambique, 2022. A) Rural sites; B) urban site; C) synthetic contact matrix derived from Mozambique-specific demographic data by Prem et. al. (12).

Figure 4

Modeled age-specific VE derived from study of human contact patterns, Mozambique, 2022. Overall VEs of a respiratory infection, comparing synthetic and empiric contact rates, are shown for rural (A) and urban (B) sites. ER, empiric rural; SR, synthetic rural; EU, empiric urban; SU, synthetic urban; VE, vaccine effectiveness.