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Incidence and Transmission of Respiratory Syncytial Virus in Urban and Rural Communities in South Africa, 2017-2018: Results of the PHIRST Cohort Study
82 Pages Posted: 11 May 2023
More...Abstract
Background: Data on RSV incidence and household transmission from sub-Saharan Africa are limited. Therefore, we describe the incidence and transmission of RSV within South African households.
Methods: We conducted a prospective cohort study in rural and urban communities during 2017-2018. Approximately 100 households were enrolled annually and followed for 10 months. Nasopharyngeal swabs were collected twice-weekly from consenting household members irrespective of symptoms and tested for RSV using real-time reverse transcription polymerase chain reaction (rRT-PCR). We calculated RSV infection incidence and household cumulative infection risk (HCIR).
Findings: We collected and tested 81,430 samples from 1,116 participants in 225 households (follow-up rate 90%). Over 10 months of follow-up, 32% (359/1116) of individuals had ≥1 RSV infection, and 75% of households (168/225) had ≥1 RSV-positive individual. RSV incidence was 47.2 infections per 100 person-years and highest in children aged <5 years (78.3); 10% (37/359) of RSV-infected individuals had a repeat RSV infection during the same season, 33% (132/396) of infections were symptomatic, and 2% (9/396) sought medical care. Symptoms were commonest in individuals aged <12 and ≥65 years. The overall HCIR was 11%; 8% (47/561), 8% (9/102), and 21% (40/193) from individuals with 0, 1, and ≥2 symptoms, respectively. Individuals aged 1-12 years accounted for 55% (134/242) of index cases. On multivariable analysis, controlling for index case age, index cases with ≥2 symptoms and whose duration of shedding was ≥4 days were more likely to transmit infection; household contacts aged 1-4 years vs. age ≥65 years were more likely to acquire infection.
Interpretation: Within two South African communities, the RSV attack rate was high, and most infections were asymptomatic. Young children were more likely to introduce RSV into the home, and to be infected, suggesting that vaccines targeting children aged <12 years could reduce household transmission in these communities.FundingUSCDC, BMGF
Trial Registration: Registered on clinicaltrials.gov on 6 August 2015 (https://clinicaltrials.gov/ct2/show/NCT02519803).
Funding: This work was supported by the National Institute for Communicable Diseases of the National Health Laboratory Service and the U.S. Centers for Disease Control and Prevention [co- operative agreement number: 5U51IP000155]. Testing for RSV was supported by the Bill and Melinda Gates Foundation (Grant number: OPP1164778).
Declaration of Interest: CC has received grant support from Sanofi Pasteur, US CDC, Welcome Trust, Programme for Applied Technologies in Health (PATH), Bill & Melinda Gates Foundation and South African Medical Research Council (SA-MRC). AvG has received grant support from CDC, ASLM/Africa CDC, SA-MRC, WHO Afro, Fleming Fund, WHO, Wellcome Trust. NW reports receiving grants from Sanofi Pasteur, US CDC and the Bill & Melinda Gates Foundation. NAM has received a grant to his institution from Pfizer to conduct research in patients with pneumonia. JM has received grant support from Sanofi Pasteur and PATH. Other authors declare that they have no conflict of interest. MC received the Robert Austrian Award sponsored by Pfizer as well as received funding as part of the South Africa-Pittsburgh Public Health Genomic Epidemiology (SAPPHGenE) training program and reports support for attending meetings and/or travel paid to the institution from Bill and Melinda Gates Foundation.
Ethical Approval: The PHIRST protocol was approved by the University of Witwatersrand Human Research Ethics Committee (Reference 150808) and the U.S. Centers for Disease Control and Prevention’s Institutional Review Board relied on the local review (#6840). Participants receive grocery store vouchers of ZAR25-30 (USD 2.00-2.50) per visit to compensate for the discomfort associated with study procedures and time required for sample collection and interview.
Keywords: respiratory syncytial virus, transmission, burden of disease, South Africa, Africa, rural, urban
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