COVID-19 Household Transmission Study (HTS)

About this project

The household transmission study (HTS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease (COVID-19), is a case-ascertained, prospective, observational household transmission study of household contacts of index cases from two urban communities in the North West Province (Klerksdorp) and the Gauteng Province (Soweto). In order to better understand the transmission dynamics of SARS-CoV-2 in households with HIV-infected and HIV-uninfected COVID-19 index cases, we screen individuals consulting at primary healthcare facilities for respiratory illness or suspected COVID-19 and test them for SARS-CoV-2. If someone tests positive for SARS-CoV-2 and reports to be the first person with respiratory or suspected COVID-19 symptoms in their household, we approach their household for enrolment in the HTS. Following enrolment, nasal swabs are collected from the index cases and their household contacts three times per week for 6 weeks’ post-enrolment to test for SARS-CoV-2, irrespective of presence of symptoms. We also collect serum at enrolment and the end of the follow-up period to test for antibodies to SARS-CoV-2. The HTS started in October 2020 and will continue until August 2021, and will help us understand if compared to HIV-uninfected individuals, HIV-infected individuals shed SARS-CoV-2 for longer, or if there is a difference risk of transmitting the virus to household contact, and to determine the incubation period and the proportion of SARS-CoV-2 individuals that have symptoms.

  1. To determine the time period (range and median) in days that HIV-infected and HIV-uninfected index cases continue to shed SARS-CoV-2 from respiratory specimens after symptoms onset using real-time reverse transcription polymerase chain reaction (rRT-PCR) and viral culture.
  2. To determine the temporal variations of SARS-CoV-2 viral-load in respiratory specimens from HIV-infected and HIV-uninfected index cases using reverse transcriptase polymerase chain reaction (rRT-PCR).
  3. To determine the secondary infection risk (SIR) in household contacts of HIV-infected and HIV-uninfected index cases.
  4. To determine the serial interval (SI) for SARS-CoV-2 transmission from HIV-infected and HIV-uninfected index cases.
  5. To determine the antibody response to SARS-CoV-2 early-post infection among HIV-infected and HIV-uninfected index cases.

This study will provide essential information on the natural history of the virus, also considering how it may differ between HIV-infected and –uninfected individuals. This will impact decisions on optimal strategies for the containment and mitigation of the current and potential future epidemics of SARS-CoV-2 locally, regionally and globally.


The study was approved by the University of the Witwatersrand Human Research Ethics Committee (Reference M2008114).


Household transmission of SARS-CoV-2 from adult index cases living with and without HIV in South Africa, 2020-2021: a case-ascertained, prospective observational household transmission study.
Kleynhans, J, Walaza, S, Martinson, NA, Neti, M, Gottberg, Av, Bhiman, JN, Toi, D, Amoako, DG, Buys, A, Ndlangisa, K, Wolter, N, Genade, L, Maloma, L, Chewparsad, J, Lebina, L, de Gouveia, L, Kotane, R, Tempia, S and Cohen, C (2022). Clinical Infectious Diseases, 2022; DOI: 10.1093/cid/ciac640
Association of close-range contact patterns with SARS-CoV-2: a household transmission study
Kleynhans, J, Dall'Amico, L, Gauvin, L, Tizzoni, M, Maloma, L, Walaza, S, Martinson, NA, von Gottberg, A, Wolter, N, Makhasi, M, Cohen, C, Cattuto, C and Tempia, S (2023). eLife 12: e84753. DOI:


Project Protocol

Funders and Collaborators

National Institute for Communicable Diseases
2 Wellcome
The Wellcome Trust
Perinatal HIV Research Unit
4 Wits
University of the Witwatersrand
The ISI Foundation
World Health Organization


HTS Sites
Soweto, Gauteng Province
Soweto is located in Gauteng Province and is a township outside of Johannesburg. Its population is 1.5 million and encompasses 150 km2. Residential areas in Soweto are located in neighbourhoods which tend to have heterogeneous housing structures between neighbourhoods, but similar housing structures within neighbourhoods. Housing structures include but are not limited to single-family houses, multi-unit dwellings, shacks within informal settlements and in the back yards of formal residences, and hostels.
Klerksdorp, North West Province
Klerksdorp is located in the local municipality of Matlosana in North West Province and has a population of over 385,000 people and is 115 km2. The city of Klerksdorp is surrounded by the townships of Jouberton, Alabama, Kanana, Khuma, and Tigane. The townships are organized into extensions that include mostly single-family houses and shacks. Prevalence of HIV in Klerksdorp is approximately 12%. Annual incidence of tuberculosis is extremely high approaching 1200/100,000 with an HIV coinfection rate of over 80%.