Networks of face-to-face social contacts in Niakhar, Senegal

Abstract

We present the first analysis of face-to-face contact network data from Niakhar, Senegal. Participants in a cluster-randomized influenza vaccine trial were interviewed about their contact patterns when they reported symptoms during their weekly household surveillance visit. We employ a negative binomial model to estimate effects of covariates on contact degree. We estimate the mean contact degree for asymptomatic Niakhar residents to be 16.5 (95% C.I. 14.3, 18.7) in the morning and 14.8 in the afternoon (95% C.I. 12.7, 16.9). We estimate that symptomatic people make 10% fewer contacts than asymptomatic people (95% C.I. 5%, 16%; p = 0.006), and those aged 0-5 make 33% fewer contacts than adults (95% C.I. 29%, 37%; p < 0.001). By explicitly modelling the partial rounding pattern observed in our data, we make inference for both the underlying (true) distribution of contacts as well as for the reported distribution. We created an estimator for homophily by compound (household) membership and estimate that 48% of contacts by symptomatic people are made to their own compound members in the morning (95% CI, 45%, 52%) and 60% in the afternoon/evening (95% CI, 56%, 64%). We did not find a significant effect of symptom status on compound homophily. We compare our findings to those from other countries and make design recommendations for future surveys.

Social contact patterns and implications for infectious disease transmission – a systematic review and meta-analysis of contact surveys

“…Senegal (Potter et al, 2019) Data were collected between August 1, 2009 to February 1, 2010 and respondents reported the number of people they contacted in their own compound on both the morning (AM) and the evening (PM) of the survey day. Next, they were asked whether they had visited a list of twelve geographic locations on the survey day, including up to five (non-home) compounds, a field, market, mosque/church, and others.…”

“…Most studies (N=10) deployed a random sampling method (e.g., through population registers), often stratified to include sufficient numbers for each age group. Five studies used a convenience sample (Grijalva et al, 2015;Kumar et al, 2018;Potter et al, 2019;Stein et al, 2014;Zhang et al, 2020) and one had no description of sampling methods (Meeyai et al, 2015).…”

A cross-sectional study measuring contact patterns using diaries in an urban and a rural community in South Africa, 2018

“…Although sub-Saharan Africa has the highest burden of infectious diseases globally, [ 4 ] data on contact patterns within the region are limited, making modelling infectious disease transmission challenging [ 5 ]. Contact studies have been carried out in Kenya, [ 6 , 7 ] Uganda, [ 8 , 9 ] Senegal, [ 10 ] Zimbabwe [ 11 ] and South Africa [ 12 , 13 ]. The South African studies were performed in Cape Town communities, and it is unknown how contact patterns reported in Cape Town compare to other South African communities.…”

Using Social Contact Data to Improve the Overall Effect Estimate of a Cluster-Randomized Influenza Vaccination Program in Senegal

“…We analyse a single contact survey per participant and restricted analysis to 3,758 contact surveys that were submitted between 1 August 2009 to 1 February 2010 because this subset had been previously cleaned and analysed extensively (Potter et al., 2019). Contact surveys were not excluded for those with negative influenza tests.…”

“…A total of 924 (24.6%) were asymptomatic 2 days before the survey while only 51 (1.4%) were asymptomatic on the day of the survey. Additionally, a social network analysis of these data found no difference in numbers of contacts recorded the day before the survey vs. 2 days prior—so there is no evidence that the earlier time point is subject to recall bias (Potter et al., 2019). The survey did not elicit how many of the morning contacts were repeated in the afternoon/evening.…”