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

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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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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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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Infection in the Graeco-Roman era with the emphasis on epidemic ilness.

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie ◽

10.4102/satnt.v32i1.331 ◽

2013 ◽

Vol 32 (1) ◽

Author(s):

Louise Cilliers ◽

Francois P. Retief

Keyword(s):

Infectious Diseases ◽

19Th Century ◽

Close Contact ◽

Acquired Immunity ◽

Epidemic Disease ◽

Western History ◽

History Of ◽

Pathogenic Organisms ◽

Micro Organisms ◽

The 19Th Century

In this article the views of the ancient Greeks and Romans on the etiology of infectious diseases are assessed. It appeared that these views were remarkably correct in many respects: Hippocrates for instance believed that an imbalance in the humours preceded disease, while we know today that a malnourished body predisposes a patient to epidemic disease. Further acute observations were recorded during the plague which afflicted Athenians in the 5th century BC, when it was noted that the disease (probably smallpox) was spread by close contact with patients and that the same person never contracted the disease twice – the first description in Western history of acquired immunity. The ancients’ theories of miasmata and ‘seeds of disease’ in the air were the forerunners of what is today identified as pathological micro-organisms causing disease. Little progress in the study of the etiology of infectious diseases was made since Graeco-Roman times, in fact, in the 19th century it was still believed in London that infection was the result of ‘bad air’. The problem was eventually solved when in the 19th century Robert Koch, with the help of the microscope, discovered the pathogenic organisms causing infectious diseases. In many respects the scientific discoveries during the last two centuries merely confirmed the observations of the ancient Greeks and Romans made more than 2000 years ago.

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A general model for the demographic signatures of the transition from pandemic emergence to endemicity

Science Advances ◽

10.1126/sciadv.abf9040 ◽

2021 ◽

Vol 7 (33) ◽

pp. eabf9040

Author(s):

Ruiyun Li ◽

C. Jessica E. Metcalf ◽

Nils Chr. Stenseth ◽

Ottar N. Bjørnstad

Keyword(s):

Human Population ◽

Disease Burden ◽

Mitigation Strategies ◽

Mathematical Framework ◽

Human Pathogens ◽

Incidence And Mortality ◽

Social Mixing ◽

Mixing Patterns ◽

Age Structured

Anticipating the medium- and long-term trajectory of pathogen emergence has acquired new urgency given the ongoing COVID-19 pandemic. For many human pathogens, the burden of disease depends on age and previous exposure. Understanding the intersection between human population demography and transmission dynamics is therefore critical. Here, we develop a realistic age-structured mathematical model that integrates demography, social mixing, and immunity to establish a plausible range for future age incidence and mortality. With respect to COVID-19, we identify a plausible transition in the age structure of risks once the disease reaches seasonal endemism across a range of immunity durations and relative severity of primary versus subsequent reinfections. We train the model using diverse real-world demographies and age-structured mixing to bound expectations for changing age incidence and disease burden. The mathematical framework is flexible and can help tailor mitigation strategies in countries worldwide with varying demographies and social mixing patterns.

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The influence of school holiday timing on epidemic impact

Epidemiology and Infection ◽

10.1017/s0950268813002884 ◽

2013 ◽

Vol 142 (9) ◽

pp. 1963-1971 ◽

Cited By ~ 9

Author(s):

K. T. D. EAMES

Keyword(s):

Mathematical Models ◽

School Closure ◽

Influenza Epidemic ◽

Final Size ◽

Peak Incidence ◽

Social Mixing ◽

Mixing Patterns ◽

The Uk ◽

The Impact

SUMMARYThe impact of reactive school closure on an epidemic is uncertain, since it is not clear how an unplanned closure will affect social mixing patterns. The effect of school holidays on social mixing patterns is better understood. Here, we use mathematical models to explore the influence of the timing of school holidays on the final size and peak incidence of an influenza-like epidemic. A well-timed holiday can reduce the impact of an epidemic, in particular substantially reducing an epidemic's peak. Final size and peak incidence cannot both be minimized: a later holiday is optimal for minimizing the final size, while an earlier holiday minimizes peak incidence. Using social mixing data from the UK, we estimated that, had the 2009 influenza epidemic not been interrupted by the school summer holidays, the final size would have been about 20% larger and the peak about 170% higher.

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Germs on a Plane: The Transmission and Risks of Airplane-Borne Diseases

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198118799709 ◽

2018 ◽

Vol 2672 (29) ◽

pp. 93-102 ◽

Cited By ~ 1

Author(s):

Nereyda L. Sevilla

Keyword(s):

Public Health ◽

Infectious Diseases ◽

Close Contact ◽

Air Travel ◽

Economic Consequences ◽

Disease Spread ◽

Pneumonic Plague ◽

Health Authorities ◽

Public Health Authorities ◽

The Impact

This research explored the role of air travel in the spread of infectious diseases, specifically severe acute respiratory syndrome (SARS), H1N1, Ebola, and pneumonic plague. Air travel provides the means for such diseases to spread internationally at extraordinary rates because infected passengers jump from coast to coast and continent to continent within hours. Outbreaks of diseases that spread from person to person test the effectiveness of current public health responses. This research used a mixed methods approach, including use of the Spatiotemporal Epidemiological Modeler, to model the spread of diseases, evaluate the impact of air travel on disease spread, and analyze the effectiveness of different public health strategies and travel policies. Modeling showed that the spread of Ebola and pneumonic plague is minimal and should not be a major air travel concern if an individual becomes infected. H1N1 and SARS have higher infection rates and air travel will facilitate the spread of disease nationally and internationally. To contain the spread of infectious diseases, aviation and public health authorities should establish tailored preventive measures at airports, capture contact information for ticketed passengers, expand the definition of “close contact,” and conduct widespread educational programs. The measures will put in place a foundation for containing the spread of infectious diseases via air travel and minimize the panic and economic consequences that may occur during an outbreak.

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