Social mixing patterns relevant to infectious diseases spread by close contact in urban Blantyre, Malawi.

Introduction: Understanding human mixing patterns relevant to infectious diseases spread through close contact is vital for modelling transmission dynamics and optimisation of disease control strategies. Mixing patterns in low-income countries like Malawi are not well understood. Methodology: We conducted a social mixing survey in urban Blantyre, Malawi between April and July 2021 (between the 2nd and 3rd wave of COVID-19 infections). Participants living in densely-populated neighbourhoods were randomly sampled and, if they consented, reported their physical and non-physical contacts within and outside homes lasting at least 5 minutes during the previous day. Age-specific mixing rates were calculated, and a negative binomial mixed effects model was used to estimate determinants of contact behaviour. Results: Of 1,201 individuals enrolled, 702 (58.5%) were female, the median age was 15 years (interquartile range [IQR] 5-32) and 127 (10.6%) were HIV-positive. On average, participants reported 10.3 contacts per day (range: 1-25). Mixing patterns were highly age-assortative, particularly those within the community and with skin-to-skin contact. Adults aged 20-49y reported the most contacts (median:11, IQR: 8-15) of all age groups; 38% (95%CI: 16-63) more than infants (median: 8, IQR: 5-10), who had the least contacts. Household contact frequency increased by 3% (95%CI 2-5) per additional household member. Unemployed participants had 15% (95%CI: 9-21) fewer contacts than other adults. Among long range (>30 meters away from home) contacts, secondary school children had the largest median contact distance from home (257m, IQR 78-761). HIV-positive status in adults >18 years-old was not associated with increased contact patterns (1%, 95%CI -9-12). During this period of relatively low COVID-19 incidence in Malawi, 301 (25.1%) individuals stated that they had limited their contact with others due to COVID-19 precautions; however, their reported contacts were not fewer (8%, 95%CI 1-13). Conclusion: In urban Malawi, contact rates, are high and age-assortative, with little behavioural change due to either HIV-status or COVID-19 circulation. This highlights the limits of contact-restriction-based mitigation strategies in such settings and the need for pandemic preparedness to better understand how contact reductions can be enabled and motivated. Keywords: Social contacts, Transmission, Mixing data, Infectious disease, Malawi, Africa

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Characteristics of human encounters and social mixing patterns relevant to infectious diseases spread by close contact: a survey in Southwest Uganda

BMC Infectious Diseases ◽

10.1186/s12879-018-3073-1 ◽

2018 ◽

Vol 18 (1) ◽

Cited By ~ 21

Author(s):

O. le Polain de Waroux ◽

S. Cohuet ◽

D. Ndazima ◽

A. J. Kucharski ◽

A. Juan-Giner ◽

...

Keyword(s):

Infectious Diseases ◽

Close Contact ◽

Social Mixing ◽

Mixing Patterns

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The influence of risk perceptions on close contact frequency during the SARS-CoV-2 pandemic

10.21203/rs.3.rs-996488/v1 ◽

2021 ◽

Author(s):

James Wambua ◽

Lisa Hermans ◽

Pietro Coletti ◽

Frederik Verelst ◽

Lander Willem ◽

...

Keyword(s):

Public Health ◽

Health Communication ◽

Risk Perceptions ◽

Close Contact ◽

Social Contact ◽

Perceived Severity ◽

Public Health Communication ◽

Contact Behaviour ◽

Contact Frequency ◽

The Impact

Abstract Human behaviour is known to be crucial in the propagation of infectious diseases through respiratory or close-contact routes like the current SARS-CoV-2 virus. Intervention measures implemented to curb the spread of the virus mainly aim at limiting the number of close contacts, until vaccine roll-out is complete. Our main objective was to assess the relationships between SARS-CoV-2 perceptions and social contact behaviour in Belgium. Understanding these relationships is crucial to maximize interventions' effectiveness, e.g. by tailoring public health communication campaigns. In this study, we surveyed a representative sample of adults in Belgium in two longitudinal surveys (8 waves of survey 1 in April 2020 to August 2020, and 11 waves of survey 2 in November 2020 to April 2021). Generalized linear mixed effects models were used to analyse the two surveys. Participants with low and neutral perceptions on perceived severity made a significantly higher number of social contacts as compared to participants with high levels of perceived severity after controlling for other variables. Furthermore, participants with higher levels of perceived effectiveness of measures and perceived adherence to measures made fewer contacts. However, the differences were small. Our results highlight the key role of perceived severity on social contact behaviour during a pandemic. Nevertheless, additional research is required to investigate the impact of public health communication on severity of COVID-19 in terms of changes in social contact behaviour.

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Social contact patterns of school-age children in Taiwan: comparison of the term time and holiday periods

Epidemiology and Infection ◽

10.1017/s0950268814001915 ◽

2014 ◽

Vol 143 (6) ◽

pp. 1139-1147 ◽

Cited By ~ 6

Author(s):

S.-C. CHEN ◽

Z.-S. YOU

Keyword(s):

Influenza Pandemic ◽

Social Contact ◽

School Closure ◽

School Age Children ◽

Individual Student ◽

School Age ◽

Skin Contact ◽

Contact Patterns ◽

Contact Behaviour ◽

Contact Frequency

SUMMARYSchool closure is one of the most common interventions in the early weeks of an influenza pandemic. Few studies have investigated social contact patterns and compared individual student contact characteristics during the school term and holiday periods in Taiwan. Here, we conducted a well-used questionnaire survey in a junior high school (grades 7–8) in June 2013. All 150 diary-based effective questionnaires covering conversation and skin-to-skin contact behaviour were surveyed. Two questionnaires for each participant were designed to investigate the individual-level difference of contact numbers per day during the two periods. The questionnaire response rate was 44%. The average number of contacts during term time (20·0 contacts per day) and holiday periods (12·6 contacts per day) were significantly different (P < 0·05). The dominant contact frequencies and duration were everyday contact (89·10%) and contacts lasting less than 5 minutes (37·09%). The greatest differences occurred within the 13–19 years age groups. The result presented in this study provide an indication of the likely reduction in daily contact frequency that might occur if a school closure policy was adopted in the event of an influenza pandemic in Taiwan. Comparing contact patterns during term time and holiday periods, the number of contacts decreased by 40%. This study is the first research to investigate the contact numbers and contact characteristics for school-age children during the school term and a holiday period in Taiwan. With regard to public health, this study could provide the basic contact information and database for modelling influenza epidemics for minimizing the spread of influenza that depends on personal contacts for transmission.

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Close contact infection dynamics over time: insights from a second large-scale social contact survey in Flanders, Belgium, in 2010-2011

10.1101/2020.09.30.20204891 ◽

2020 ◽

Cited By ~ 2

Author(s):

Thang Van Hoang ◽

Pietro Coletti ◽

Yimer Wasihun Kiffe ◽

Kim Van Kerckhove ◽

Sarah Vercruysse ◽

...

Keyword(s):

Large Scale ◽

Close Contact ◽

Social Contact ◽

Contact Rates ◽

Contact Patterns ◽

Time Period ◽

Social Mixing ◽

Mixing Patterns ◽

Contact Survey ◽

The Impact

AbstractBackgroundIn 2010-2011, we conducted a social contact survey in Flanders, Belgium, aimed at improving and extending the design of the first social contact survey conducted in Belgium in 2006. This second social contact survey aimed to enable, for the first time, the estimation of social mixing patterns for an age range of 0 to 99 years and the investigation of whether contact rates remain stable over this 5-year time period.MethodsDifferent data mining techniques are used to explore the data, and the age-specific number of social contacts and the age-specific contact rates are modelled using a GAMLSS model. We compare different matrices using assortativeness measures. The relative change in the basic reproduction number (R0) and the ratio of relative incidences with 95% bootstrap confidence intervals (BCI) are employed to investigate and quantify the impact on epidemic spread due to differences in gender, day of the week, holiday vs. regular periods and changes in mixing patterns over the 5-year time gap between the 2006 and 2010-2011 surveys. Finally, we compare the fit of the contact matrices in 2006 and 2010-2011 to Varicella serological data.ResultsAll estimated contact patterns featured strong homophily in age and gender, especially for small children and adolescents. A 30% (95% BCI [17%; 37%] ) and 29% (95% BCI [14%; 40%] ) reduction in R0 was observed for weekend versus weekdays and for holiday versus regular periods, respectively. Significantly more interactions between people aged 60+ years and their grandchildren were observed on holiday and weekend days than on regular weekdays. Comparing contact patterns using different methods did not show any substantial differences over the 5-year time period under study.ConclusionsThe second social contact survey in Flanders, Belgium, endorses the findings of its 2006 predecessor and adds important information on the social mixing patterns of people older than 60 years of age. Based on this analysis, the mixing patterns of people older than 60 years exhibit considerable heterogeneity, and overall, the comparison of the two surveys shows that social contact rates can be assumed stable in Flanders over a time span of 5 years.

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Close contact infection dynamics over time: insights from a second large-scale social contact survey in Flanders, Belgium, in 2010-2011

BMC Infectious Diseases ◽

10.1186/s12879-021-05949-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Thang Van Hoang ◽

Pietro Coletti ◽

Yimer Wasihun Kifle ◽

Kim Van Kerckhove ◽

Sarah Vercruysse ◽

...

Keyword(s):

Close Contact ◽

Social Contact ◽

Additive Models ◽

Contact Rates ◽

Contact Patterns ◽

Time Period ◽

Social Mixing ◽

Mixing Patterns ◽

Contact Survey ◽

The Impact

Abstract Background In 2010-2011, we conducted a social contact survey in Flanders, Belgium, aimed at improving and extending the design of the first social contact survey conducted in Belgium in 2006. This second social contact survey aimed to enable, for the first time, the estimation of social mixing patterns for an age range of 0 to 99 years and the investigation of whether contact rates remain stable over this 5-year time period. Methods Different data mining techniques are used to explore the data, and the age-specific number of social contacts and the age-specific contact rates are modelled using a generalized additive models for location, scale and shape (GAMLSS) model. We compare different matrices using assortativeness measures. The relative change in the basic reproduction number (R0) and the ratio of relative incidences with 95% bootstrap confidence intervals (BCI) are employed to investigate and quantify the impact on epidemic spread due to differences in sex, day of the week, holiday vs. regular periods and changes in mixing patterns over the 5-year time gap between the 2006 and 2010-2011 surveys. Finally, we compare the fit of the contact matrices in 2006 and 2010-2011 to Varicella serological data. Results All estimated contact patterns featured strong homophily in age and sex, especially for small children and adolescents. A 30% (95% BCI [17%; 37%]) and 29% (95% BCI [14%; 40%]) reduction in R0 was observed for weekend versus weekdays and for holiday versus regular periods, respectively. Significantly more interactions between people aged 60+ years and their grandchildren were observed on holiday and weekend days than on regular weekdays. Comparing contact patterns using different methods did not show any substantial differences over the 5-year time period under study. Conclusions The second social contact survey in Flanders, Belgium, endorses the findings of its 2006 predecessor and adds important information on the social mixing patterns of people older than 60 years of age. Based on this analysis, the mixing patterns of people older than 60 years exhibit considerable heterogeneity, and overall, the comparison of the two surveys shows that social contact rates can be assumed stable in Flanders over a time span of 5 years.

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Shielding individuals at high risk of COVID-19: a micro-simulation study

10.1101/2022.01.03.22268675 ◽

2022 ◽

Author(s):

Kevin van Zandvoort ◽

Caroline Favas ◽

Francesco Checchi

Keyword(s):

High Risk ◽

Low Income ◽

Reproduction Number ◽

Severe Disease ◽

Sensitivity Analyses ◽

Mitigation Measures ◽

Internally Displaced ◽

Social Mixing ◽

Micro Simulation ◽

Mixing Patterns

Background One of the proposed interventions for mitigating COVID-19 epidemics, particularly in low-income and crisis-affected settings, is to physically isolate individuals known to be at high risk of severe disease and death due to age or co-morbidities. This intervention, known as 'shielding', could be implemented in various ways. If shielded people are grouped together in residences and isolation is imperfect, any introduction of infections within the shielding group could cause substantial mortality and thus negate the intervention's benefits. We explored the effectiveness of shielding under various modalities of implementation and considered mitigation measures to reduce its possible harms. Methods We used an individual-based mathematical model to simulate the evolution of a COVID-19 epidemic in a population of which a fraction above a given age cut-off are relocated to shielding residences, in which they have variable levels of contacts with their original household, the outside world and fellow shielding residents. We set our simulation with the context of an internally displaced persons' camp in Somaliland, for which we had recently collected data on household demographics and social mixing patterns. We compared an unmitigated epidemic with a shielding intervention accompanied by various measures to reduce the risk of virus introduction and spread within the shielding residences. We did sensitivity analyses to explore parameters such as residence size, reduction in contacts, basic reproduction number, and prior immunity in the population. Results Shielded residences are likely to be breached with infection during the outbreak. Nonetheless, shielding can be effective in preventing COVID-19 infections in the shielded population. The effectiveness of shielding is mostly affected by the size of the shielded residence, and by the degree by which contacts between shielded and unshielded individuals are reduced. Reductions in contacts between shielded individuals could further increase the effectiveness of shielding, but is only effective in larger shielded residences. Large shielded residences increase the risk of infection, unless very large reductions in contacts can be achieved. In epidemics with a lower reproduction number, the effectiveness of shielding could be negative effectiveness. Discussion Shielding could be an effective method to protect the most at-risk individuals. It should be considered where other measures cannot easily be implemented, but with attention to the epidemiological situation. Shielding should only be implemented through small to medium-sized shielding residences, with appropriate mitigation measures such as reduced contact intensity between shielded individuals and self-isolation of cases to prevent subsequent spread.

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Correlates of HIV, STI and TB among sub-Saharan African migrants in Lisbon: a biobehavioral study

European Journal of Public Health ◽

10.1093/eurpub/ckaa166.817 ◽

2020 ◽

Vol 30 (Supplement_5) ◽

Author(s):

S Dias ◽

A Gama ◽

D Simões ◽

E Carreiras ◽

C Mora ◽

...

Keyword(s):

Infectious Diseases ◽

Hiv Testing ◽

Social Determinants ◽

Low Income ◽

Social Inequalities ◽

Rapid Test ◽

Hiv Positive ◽

The Past ◽

African Migrants ◽

Sub Saharan

Abstract Sub-Saharan African migrants (SAMs) have been disproportionately affected by infectious diseases such as HIV, other sexually transmitted infections (STIs) and Tuberculosis infection (TB). Research on infectious diseases and related factors among migrant populations is critical to further understand these populations' health needs and inform prevention strategies. However, migrants are often underrepresented in national statistics and research. This study aimed to examine correlates of HIV, past STI and past TB among SAMs. A venue-based sample of 790 SSAMs completed a cross-sectional biobehavioral survey on sexual practices, HIV testing and self-reported infectious diseases; an HIV rapid test was offered. Uni- and multivariable logistic regression analyses were performed to examine factors associated with HIV, past STI and past TB. Overall, 5.4% of participants were HIV-positive and 16.7% reported a past STI. Odds of being HIV positive increased by age (OR 1.07, 95%CI 1.03-1.11) and were higher among those who experienced violence from a partner (OR 2.77, 95%CI 1.08-7.10). Increased odds of having a past STI were found among migrants with low income (OR 2.86, 95%CI 1.48-5.56), long-term migrants (>25 years residing in Portugal: OR 2.16, 95%CI 1.06-4.38) and those who reported sexual risk behaviors (≥3 sexual partners: OR 2.06, 95%CI 1.14-3.70; inconsistent condom use: OR 2.61, 95%CI 1.32-5.17). In total, 4.1% of participants had TB in the past; these were more likely male (OR 3.42, 95%CI 1.29-9.06) and HIV positive (OR 11.48, 95%CI 4.55-28.94). Half of the participants had never been tested for HIV before, including over a third of those who had STI or TB in the past. Efforts are needed to reduce missed opportunities for HIV/STIs prevention and uptake of HIV testing among SSAMs through more integrated care, while addressing social determinants of infectious diseases. Key messages High levels of HIV, STI and TB infection among SAMs were found to be strongly associated with socioeconomic disadvantage and poor living conditions in the host country. Social inequalities are persistently a major factor affecting risk for HIV, STIs and TB, and thus addressing social determinants of infectious diseases must remain a public health priority.

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Mixing patterns and the spread of close-contact infectious diseases

Emerging Themes in Epidemiology ◽

10.1186/1742-7622-3-10 ◽

2006 ◽

Vol 3 (1) ◽

Cited By ~ 73

Author(s):

WJ Edmunds ◽

G Kafatos ◽

J Wallinga ◽

JR Mossong

Keyword(s):

Infectious Diseases ◽

Close Contact ◽

Mixing Patterns

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Social mixing patterns for transmission models of close contact infections: exploring self-evaluation and diary-based data collection through a web-based interface

Epidemiology and Infection ◽

10.1017/s0950268806006418 ◽

2006 ◽

Vol 134 (6) ◽

pp. 1158-1166 ◽

Cited By ~ 77

Author(s):

P. BEUTELS ◽

Z. SHKEDY ◽

M. AERTS ◽

P. VAN DAMME

Keyword(s):

Close Contact ◽

Social Contact ◽

Convenience Sample ◽

Web Based ◽

Self Evaluation ◽

Social Mixing ◽

Contact Data ◽

Mixing Patterns ◽

The Difference ◽

Transmission Models

Although mixing patterns are crucial in dynamic transmission models of close contact infections, they are largely estimated by intuition. Using a convenience sample (n=73), we tested self-evaluation and prospective diary surveys with a web-based interface, in order to obtain social contact data. The number of recorded contacts was significantly (P<0·01) greater on workdays (18·1) vs. weekend days (12·3) for conversations, and vice versa for touching (5·4 and 7·2 respectively). Mixing was highly assortative with age for both (adults contacting other adults vs. 0- to 5-year-olds, odds ratio 8·9–10·8). Respondents shared a closed environment significantly more often with >20 other adults than with >20 children. The difference in number of contacts per day was non-significant between self-evaluation and diary (P=0·619 for conversations, P=0·125 for touching). We conclude that self-evaluation could yield similar results to diary surveys for general or very recent mixing information. More detailed data could be collected by diary, at little effort to respondents.

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Low socioeconomic status is associated with self-reported HIV positive status among young MSM in Brazil and Peru

BMC Infectious Diseases ◽

10.1186/s12879-021-06455-3 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Thiago S. Torres ◽

Lara E. Coelho ◽

Kelika A. Konda ◽

E. Hamid Vega-Ramirez ◽

Oliver A. Elorreaga ◽

...

Keyword(s):

Socioeconomic Status ◽

Latin American ◽

Low Socioeconomic Status ◽

Low Income ◽

Sexual Attraction ◽

Hiv Positive ◽

Sociodemographic Characteristics ◽

Hiv Status ◽

Hiv Test ◽

Young Msm

Abstract Background Despite efforts to stop HIV epidemic in Latin America, new HIV cases continue to increase in the region especially among young MSM (YMSM). This study aims to assess if sociodemographic characteristics are associated with self-reported HIV positive status among YMSM from three Latin American countries. Methods Cross-sectional web-based survey advertised on dating apps (Grindr and Hornet) and Facebook in Brazil, Mexico and Peru. For this analysis, we included YMSM aged 18–24 years who self-reported their HIV status. We used multivariable logistic regression models for each country separately to verify if sociodemographic characteristics (race, education and income) were associated with HIV self-reported status after adjusting for behavior characteristics (sexual attraction and steady partner). Results Among 43,687 MSM who initiated the questionnaire, 27,318 (62.5%) reported their HIV status; 7001 (25.6%) of whom were YMSM. Most YMSM (83.4%) reported an HIV test in the past year, and 15.7% reported an HIV positive status in Peru, 8.4% in Mexico and 7.7% in Brazil. In adjusted models, low-income was associated with higher odds of self-reported HIV positive status in Brazil (aOR = 1.33, 95%CI: 1.01–1.75) and Peru (aOR = 1.56, 95%CI: 1.02–2.40), but not in Mexico. Lower education was associated with higher odds of self-reported HIV positive status only in Brazil (aOR = 1.35, 95%CI: 1.05–1.75). Conclusions In this large, cross-country study, self-reported HIV positive status among YMSM was high. Lower socioeconomic status was associated with higher odds of self-reported HIV positive status in Brazil and Peru. There is an urgent need for HIV prevention interventions targeting YMSM, and efforts to address low-income YMSM are especially needed in Peru and Brazil.

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