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Indirect effectiveness of a novel SARS-COV-2 vaccine (SCB-2019) in unvaccinated household contacts in the Philippines: a cluster randomised analysis

Background - Though observational evidence supports indirect effects of SARS-CoV-2 vaccines, randomised experiments are lacking. To address this gap, the double-blinded, prospective follow-up of the household contacts (HHCs) of Philippine participants of the individually-randomised, placebo-controll...

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Main Authors: Aziz, Asma Binte (Author) , Sugimoto, Jonathan Dewing (Author) , Hong, Sye Lim (Author) , You, Young Ae (Author) , Bravo, Lulu (Author) , Roa, Camilo (Author) , Borja-Tabora, Charissa (Author) , Montellano, May Emmeline B. (Author) , Carlos, Josefina (Author) , Los Reyes, Mari Rose A. de (Author) , Alberto, Edison R. (Author) , Salvani-Bautista, Milagros (Author) , Kim, Hwa Young (Author) , Njau, Irene (Author) , Clemens, Ralf (Author) , Marks, Florian (Author) , Tadesse, Birkneh Tilahun (Author)
Format: Article (Journal)
Language:English
Published: October 2024
In: Journal of infection
Year: 2024, Volume: 89, Issue: 4, Pages: [1]-12
ISSN:1532-2742
DOI:10.1016/j.jinf.2024.106260
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1016/j.jinf.2024.106260
Verlag, kostenfrei, Volltext: https://www.sciencedirect.com/science/article/pii/S0163445324001944
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Author Notes:Asma Binte Aziz, Jonathan Dewing Sugimoto, Sye Lim Hong, Young Ae You, Lulu Bravo, Camilo Roa, Charissa Borja-Tabora, May Emmeline B. Montellano, Josefina Carlos, Mari Rose A. de Los Reyes, Edison R. Alberto, Milagros Salvani-Bautista, Hwa Young Kim, Irene Njau, Ralf Clemens, Florian Marks, Birkneh Tilahun Tadesse
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Summary:Background - Though observational evidence supports indirect effects of SARS-CoV-2 vaccines, randomised experiments are lacking. To address this gap, the double-blinded, prospective follow-up of the household contacts (HHCs) of Philippine participants of the individually-randomised, placebo-controlled trial of the adjuvanted-subunit protein COVID-19 vaccine, SCB-2019, (EudraCT, 2020-004272-17; ClinicalTrials.gov, NCT04672395) was analyzed in a cluster-randomised fashion. - Methods - Over an eight-week period, HHCs were followed by rRT-PCR and paired rapid antibody tests (RATs) to detect symptomatic (SCI, primary) and all (ACI, secondary) SARS-CoV-2 infection. A standard analysis estimated the indirect effectiveness of SCB-2019 for each endpoint, excluding HHC RAT-positive at enrollment. A secondary analysis employed enzyme-linked immunosorbent assay (ELISA) results to correct for suspected bias. - Findings - SCB-2019 (N = 3470) and placebo (N = 3225) exposed HHCs contributed to at least one analysis. The standard analysis estimated that SCB-2019 reduced the risk of SCI by 83% (95% confidence/credible interval [CI: 32% to 96%), with no effect against ACI. The bias-corrected relative risk reduction was 97% (95% CI: 74% to 100%) for SCI and 79% (95% CI: 14% to 96%) for ACI, with an estimated one SARS-CoV-2 infection prevented per 4.8 households where one member received SCB-2019. - Interpretation - SCB-2019 demonstrated bias-corrected indirect effectiveness against SARS-CoV-2 infection among HHC, even at a modest coverage level in the household (approximately 25%). Further research into the indirect effects of SARS-CoV-2 vaccines is needed to optimize the impact of limited doses in low and middle-income settings.
Item Description:Gesehen am 23.04.2025
Physical Description:Online Resource
ISSN:1532-2742
DOI:10.1016/j.jinf.2024.106260

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