Modeling the interplay between demography, social contact patterns, and SARS-CoV-2 transmission in the South West Shewa Zone of Oromia Region, Ethiopia

Abstract

Background COVID-19 spread may have a dramatic impact in countries with vulnerable economies and limited availability of, and access to, healthcare resources and infrastructures. However, in sub-Saharan Africa, a low prevalence and mortality have been observed so far. Methods We collected data on individuals’ social contacts in the South West Shewa Zone (SWSZ) of Ethiopia across geographical contexts characterized by heterogeneous population density, work and travel opportunities, and access to primary care. We assessed how socio-demographic factors and observed mixing patterns can influence the COVID-19 disease burden, by simulating SARS-CoV-2 transmission in remote settlements, rural villages, and urban neighborhoods, under school closure mandate. Results From national surveillance data, we estimated a net reproduction number of 1.62 (95% CI 1.55–1.70). We found that, at the end of an epidemic mitigated by school closure alone, 10–15% of the population residing in the SWSZ would have been symptomatic and 0.3–0.4% of the population would require mechanical ventilation and/or possibly result in a fatal outcome. Higher infection attack rates are expected in more urbanized areas, but the highest incidence of critical disease is expected in remote subsistence farming settlements. School closure contributed to reduce the reproduction number by 49% and the attack rate of infections by 28–34%. Conclusions Our results suggest that the relatively low burden of COVID-19 in Ethiopia observed so far may depend on social mixing patterns, underlying demography, and the enacted school closures. Our findings highlight that socio-demographic factors can also determine marked heterogeneities across different geographical contexts within the same region, and they contribute to understand why sub-Saharan Africa is experiencing a relatively lower attack rate of severe cases compared to high-income countries.

A quantitative assessment of epidemiological parameters required to investigate COVID-19 burden

“…Mathematical modeling has been one of the cornerstones in the response to the COVID-19 pandemic ( Chinazzi et al, 2020 , Ferguson et al, 2020 , Guzzetta et al, 2021 , Hellewell et al, 2020 , Kucharski et al, 2020 , Marziano et al, 2021 , McCombs and Kadelka, 2020 , Salje et al, 2020 , Trentini et al, 2021 , Vespignani et al, 2020 , Wu et al, 2020a ). To provide solid estimates, models need to be properly calibrated based on empirical evidence ( Biggerstaff et al, 2020 , He et al, 2020 , Ma et al, 2020 , Salje et al, 2020 , Wood et al, 2021 ).…”

Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility

“…We analyzed the frequency distribution of daily contacts of study participants for a set of covariates, including their age, sex, employment status, a dichotomous variable that indicates whether the study participant had a contact with a SARS-CoV-2 positive case in the three weeks preceding the interview, and the restriction tier at the time of interview. Repeated encounters reported with the same individual counted as one contact only, following the same approach used elsewhere ( Melegaro et al, 2017 , Trentini et al, 2021 ).…”

“…We analyzed the mean number of daily contacts reported by respondents after grouping by age (one age group for individuals between 0 and 20 years of age, five 10-year age groups from 20 to 69 years, and one for individuals aged 70 years or older) and by tier (white, yellow, orange, and red). We estimated contact matrices where each element c i i represents the mean number of daily contacts study participants in age class i have with individuals of age class j, considering both physical and non-physical contacts and adjusting for reciprocity as in ( Melegaro et al, 2017 , Trentini et al, 2021 ) (see the Appendix for further details).…”

“…To correct for the selection bias in our sample, we performed 1,000 bootstrapped samples by sampling with replacement a number of interviews equal to the original sample size in each tier and choosing the age of the participant with probability proportional to the age distribution in the metropolitan city of Milan ( Zhang et al, 2020 Jun 26 , Trentini et al, 2021 ).…”

O trabalho remoto de enfermeiros docentes em tempos de pandemia

“…As medidas de distanciamento social podem reduzir entre 60 e 70% as interações sociais quando comparado ao período pré-pandemia 6 ; e o fechamento das escolas, em 48,9% o número de reprodução do vírus. Não obstante, na ausência de qualquer intervenção, a taxa de ataque esperada é de 28,3 a 34,6% 7 . Estudo estimou, para a Irlanda do Norte, que um bloqueio rigoroso com escolas fechadas reduziu em 35% a reprodução do vírus, e para o País de Gales, em 44%.…”