Association of close-range contact patterns with SARS-CoV-2: a household transmission study

Abstract
Data availability
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Abstract

Background: Households are an important location for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, especially during periods where travel and work was restricted to essential services. We aimed to assess the association of close-range contact patterns with SARS-CoV-2 transmission.

Methods: We deployed proximity sensors for two weeks to measure face-to-face interactions between household members after SARS-CoV-2 was identified in the household, in South Africa, 2020 - 2021. We calculated duration, frequency and average duration of close range proximity events with SARS-CoV-2 index cases. We assessed the association of contact parameters with SARS-CoV-2 transmission using mixed effects logistic regression accounting for index and household member characteristics.

Results: We included 340 individuals (88 SARS-CoV-2 index cases and 252 household members). On multivariable analysis, factors associated with SARS-CoV-2 acquisition were index cases with minimum C_t value <30 (aOR 10.6 95%CI 1.4-80.1) vs >35, and female contacts (aOR 2.4 95%CI 1.2-4.8). No contact parameters were associated with acquisition (aOR 1.0-1.1) for any of the duration, frequency, cumulative time in contact or average duration parameters.

Conclusion: We did not find an association between close-range proximity events and SARS-CoV-2 household transmission. Our findings may be due to study limitations, that droplet-mediated transmission during close-proximity contacts play a smaller role than airborne transmission of SARS-CoV-2 in the household, or due to high contact rates in households.

Funding: Wellcome Trust (Grant number 221003/Z/20/Z) in collaboration with the Foreign, Commonwealth and Development Office, United Kingdom.

Data availability

The contact network, selected individual characteristics and analysis script are available at https://github.com/crdm-nicd/sashts.git.

Article and author information

Author details

Jackie Kleynhans

National Health Laboratory Service, Sandringham, South Africa

For correspondence
jackiel@nicd.ac.za

Competing interests
Jackie Kleynhans, reports institutional grant funding from UK Foreign, Commonwealth and Development Office, Wellcome Trust, WHO AFRO, Africa Pathogen Genomics Initiative (Africa PGI) through African Society of Laboratory Medicine (ASLM) and Africa CDC, US Centers for Disease Control and Prevention, South African Medical Research Council (SAMRC) and UK Department of Health and Social Care and managed by the Fleming Fund: SEQAFRICA project. The author has no other competing interests to declare..

"This ORCID iD identifies the author of this article:" 0000-0001-7081-6273
Lorenzo Dall'Amico

ISI Foundation, Turin, Italy

Competing interests
Lorenzo Dall'Amico, received support from the European Union's Horizon 2a020 research and innovation programme under grant agreements No. 101003688 (EpiPose) and No. 101016233 (PERISCOPE). The author acknowledges support from the Lagrange Project of ISI Foundation funded by CRT Foundation. They were awarded a PhD contract with Grenoble INP, and received support for attending meetings/travel from the ISP Foundation and Grenoble INP. The author has no other competing interests to declare..
Laetitia Gauvin

ISI Foundation, Turin, Italy

Competing interests
Laetitia Gauvin, has received Payment or honoraria for lectures from the University of Torino, Italy. They received support from the Lagrange Project of ISI Foundation funded by CRT Foundation. The authors has no other competing interests to declare..
Michele Tizzoni

ISI Foundation, Turin, Italy

Competing interests
Michele Tizzoni, acknowledges support from the Lagrange Project of ISI Foundation funded by CRT Foundation..
Lucia Maloma

Perinatal HIV Research Unit, University of the Witwatersrand, Soweto, South Africa

Competing interests
No competing interests declared.
Sibongile Walaza

National Health Laboratory Service, Sandringham, South Africa

Competing interests
Sibongile Walaza, reports institutional grant funding from WHO AFRO, Africa Pathogen Genomics Initiative (Africa PGI) through African Society of Laboratory Medicine (ASLM) and Africa CDC, US Centers for Disease Control and Prevention, South African Medical Research Council (SAMRC), UK Department of Health and Social Care and managed by the Fleming Fund: SEQAFRICA project and the Wellcome Trust. The author has no other competing interests to declare..
Neil A Martinson

Perinatal HIV Research Unit, University of the Witwatersrand, Soweto, South Africa

Competing interests
Neil A Martinson, received grant funds from Pfizer. They participated on the data safety monitoring board of a TB HDT trial, and on the Scientific Advisory Board of a trial of an electronic reminder to take daily TB treatment. They hold an unpaid leadership role at the Setshaba Research Center. The authors has no other competing interests to declare..
Anne von Gottberg

National Health Laboratory Service, Sandringham, South Africa

Competing interests
Anne von Gottberg, reports receiving grant funds from Sanofi Pasteur and Bill & Melinda Gates Foundation. They act as chairperson of the National Advisory Group on Immunisation. The author has no other competing interests to declare..

"This ORCID iD identifies the author of this article:" 0000-0002-0243-7455
Nicole Wolter

National Health Laboratory Service, Sandringham, South Africa

Competing interests
Nicole Wolter, received grants from Sanofi Pasteur and Bill & Melinda Gates Foundation, and from US Centers for Disease Control and Prevention. The author has no other competing interests to declare..
Mvuyo Makhasi

National Health Laboratory Service, Sandringham, South Africa

Competing interests
No competing interests declared.
Cheryl Cohen

National Health Laboratory Service, Sandringham, South Africa

Competing interests
Cheryl Cohen, has received grant support from Sanofi Pasteur, US Centers for Disease Control and Prevention, Welcome Trust, Programme for Applied Technologies in Health (PATH), Bill & Melinda Gates Foundation and South African Medical Research Council (SA-MRC). The author has no other competing interests to declare..
Ciro Cattuto

Department of Informatics, University of Turin, Turin, Italy

Competing interests
Ciro Cattuto, received support from the European Union's Horizon 2020 research and innovation programme under grant agreements No. 101003688 (EpiPose) and No. 101016233 (PERISCOPE), and from Fondation Botnar, EPFL COVID-19 Real Time Epidemiology I-DAIR Pathfinder. They also received support from the Lagrange Project of ISI Foundation funded by CRT Foundation, and received equipment from the European Space Agency. They were issued the patent US8660490B2. They received support for attending meetings/travel from Gulbenkian Foundation, and participate as a Steering Board Member at CRT Foundation, on the Advisory Board at The Data Guild and on the Advisory Board in GovLab's 100 Questions Initiative and Open Data Policy Lab. The authors has no other competing interests to declare..
Stefano Tempia

National Health Laboratory Service, Sandringham, South Africa

Competing interests
No competing interests declared.

Funding

Wellcome Trust (221003/Z/20/Z)

Cheryl Cohen

Horizon 2020 Framework Programme (101016233)

Ciro Cattuto

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: The study protocol was reviewed and approved by University of the Witwatersrand Human Research Ethics Committee (Reference M2008114). The study was structured in accordance with the Declaration of Helsinki. Written informed consent was obtained from all household members aged {greater than or equal to}18 years; assent was obtained from children aged 7-17 years, and consent from a parent/ guardian of children aged <18 years. Informed consent was administered by a study team member who explained the study and requirements to participants, and shared an information leaflet with participants to keep. Consent included the enrolment into the study and all required procedures, as well as the anonymous processing of personal data for the final study report. Participants in follow-up received grocery store vouchers of USD 3 per visit to compensate for time required for specimen collection and interview, and an additional voucher once proximity sensors were returned with no visible damage.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.