Abstract
Serum neutralizing antibodies (nAbs) induced by vaccination have been linked to protection against symptomatic and severe coronavirus disease 2019. However, much less is known about the efficacy of nAbs in preventing the acquisition of infection, especially in the context of natural immunity and against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune-escape variants. Here we conducted mediation analysis to assess serum nAbs induced by prior SARS-CoV-2 infections as potential correlates of protection against Delta and Omicron infections, in rural and urban household cohorts in South Africa. We find that, in the Delta wave, D614G nAbs mediate 37% (95% confidence interval: 34–40%) of the total protection against infection conferred by prior exposure to SARS-CoV-2, and that protection decreases with waning immunity. In contrast, Omicron BA.1 nAbs mediate 11% (95% confidence interval: 9–12%) of the total protection against Omicron BA.1 or BA.2 infections, due to Omicron’s neutralization escape. These findings underscore that correlates of protection mediated through nAbs are variant specific, and that boosting of nAbs against circulating variants might restore or confer immune protection lost due to nAb waning and/or immune escape. However, the majority of immune protection against SARS-CoV-2 conferred by natural infection cannot be fully explained by serum nAbs alone. Measuring these and other immune markers including T cell responses, both in the serum and in other compartments such as the nasal mucosa, may be required to comprehensively understand and predict immune protection against SARS-CoV-2.
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Data availability
Aggregate data to reproduce the figures are available at Zenodo via https://doi.org/10.5281/zenodo.11375487 (ref. 58). Individual-level data cannot be publicly shared because of ethical restrictions and the potential for identifying included individuals. Accessing individual participant data and a data dictionary defining each field in the dataset would require provision of protocol and ethics approval for the proposed use. To request individual participant data access, please submit a proposal to C.C. who will respond within 1 month of request. Upon approval, data can be made available through a data sharing agreement.
Code availability
Code to reproduce the figures, using Python version 3.8.11 and SciPy version 1.7.1, is available at Zenodo via https://doi.org/10.5281/zenodo.11375487 (ref. 58).
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Acknowledgements
We thank all the participants who kindly agreed to take part in the study, as well as the PHIRST-C group. We are grateful to B. J. Cowling and M. E. Halloran for their insightful feedback on the paper. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institutes of Health or the US Centers for Disease Control and Prevention. This work was supported by the National Institute for Communicable Diseases of the National Health Laboratory Service and the US Centers for Disease Control and Prevention (cooperative agreement no. 6 U01IP001048) and the Wellcome Trust (grant no. 221003/Z/20/Z) in collaboration with the Foreign, Commonwealth and Development Office, United Kingdom. P.L.M. and J.N.B. are supported by the Bill and Melinda Gates Foundation through the Global Immunology and Immune Sequencing for Epidemic Response (GIISER) program (INV-030570) and receive funding from the Wellcome Trust (226137/Z/22/Z). P.L.M. is supported by the South African Research Chairs Initiative of the Department of Science and Innovation and National Research Foundation of South Africa and the SA Medical Research Council SHIP program.
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K.S., J.N.B., S.T., J.K., A.v.G., M.L.M., N.W., J.M., N.A.M., K.K., L.L., C.V., P.L.M. and C.C. designed the experiments. J.N.B., C.C., J.K., P.L.M. and S.T. accessed and verified the underlying data. J.N.B., S.T., J.K., V.S.M., Q.M., H.K., A.v.G., M.L.M., N.W., J.M., M.C., N.A.M., K.K., L.L., J.d.T., T.M., P.L.M. and C.C. collected the data and performed laboratory experiments. K.S., J.N.B., S.T., J.K., A.v.G., M.L.M., N.W., J.M., M.C., N.A.M., K.K., L.L., J.d.T., T.M., C.V. and C.C. analyzed the data and interpreted the results. K.S., J.N.B., C.V., P.L.M. and C.C. drafted the paper. All authors critically reviewed the paper. All authors had access to all the data reported in the study.
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C.C. has received grant support from Sanofi Pasteur, the US Centers for Disease Control and Prevention, the Bill & Melinda Gates Foundation, the Taskforce for Global Health, the Wellcome Trust and the South African Medical Research Council. A.v.G. has received grant support from Sanofi Pasteur, Pfizer related to pneumococcal vaccine, the US Centers for Disease Control and Prevention and the Bill & Melinda Gates Foundation. N.W. reports grants from Sanofi Pasteur and the Bill & Melinda Gates Foundation. N.A.M. has received an institutional grant from Pfizer to conduct research in patients with pneumonia and from Roche to collect specimens to assess a novel tuberculosis assay. J.M. has received grant support from Sanofi Pasteur. The other authors declare no competing interests.
Ethics
The PHIRST-C protocol was approved by the University of Witwatersrand Human Research Ethics Committee (ref. 150808), and the US Centers for Disease Control and Prevention’s Institutional Review Board relied on the local review (no. 6840). The protocol was registered on ClinicalTrials.gov on 6 August 2015 and updated on 30 December 2020 (NCT02519803). Participants receive grocery store vouchers of ZAR50 (USD 3) per visit to compensate for time required for specimen collection and interview. All participants provided written informed consent for study participation. For minors, consent was obtained from the parent or guardian.
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Extended data
Extended Data Fig. 1 Flowchart of participants included in the Delta-wave subgroup analysis.
Grey boxes represent participants excluded from the Delta-wave subgroup analysis. *Based on a previously published study31. †Household with more than 6 infected individuals would be computationally intractable to track all possible transmission chain configurations (Methods Section 3).
Extended Data Fig. 2 Flowchart of participants included in the Omicron-wave subgroup analysis.
Grey boxes represent participants excluded from the Omicron-wave subgroup analysis. *Based on a previously published study31. †Household with more than 6 infected individuals would be computationally intractable to track all possible transmission chain configurations (Methods Section 3).
Extended Data Fig. 3 D614G spike binding antibody (bAb) level for the Delta wave and the Omicron wave analysis.
a, for Delta wave subgroup, the distribution of the peak bAb level to BD5 (light blue dots) and the D614G spike bAb level at BD5 (dark blue dots), among individuals who had one prior SARS-CoV-2 infection before blood draw 5. Each dot represents one individual, with two measurements of the same individual connected through a gray line. OD: absorbance at 450 nm, measured in optical density; \(\bar{\text{OD}}:\) the average of OD; \(\bar{\text{OD}}:\) the average drop of OD. b, for Delta wave subgroup, the distribution of the peak D614G spike bAb up to BD5, stratified by individuals who were infected during the Delta wave (solid bar) vs those who were not infected (dashed bar). Independent samples t-test (two-sided) is used to determine the statistical significance (anti reported on the legend) of difference between the \(\bar{\text{OD}}\) of the two groups. c, same as b but for D614G spike bAb level at BD5. d, same as b but for \(\Delta {bA}{b}^{W}\). e, for Omicron wave subgroup, the distribution of the peak bAb level to BD8 (light red dots) and the D614G spike bAb level at BD8 (dark red dots), among individuals who had one prior SARS-CoV-2 infection before BD8. Each dot represents one individual, with two measurements of the same individual connected through a gray line. f, for the Omicron wave subgroup, the distribution of the D614G spike bAb level at BD8, stratified by individuals who were infected during the Omicron wave (solid bar) vs those who were not infected (dashed bar). Independent samples t-test (two-sided) is used to determine the statistical significance (p-value reported on the legend) of difference between the \(\bar{\text{OD}}\) s of the two groups. g, same as f but for D614G spike bAb level at BD8. h, same as f but for \(\Delta {bA}{b}^{W}\).
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Sun, K., Bhiman, J.N., Tempia, S. et al. SARS-CoV-2 correlates of protection from infection against variants of concern. Nat Med 30, 2805–2812 (2024). https://doi.org/10.1038/s41591-024-03131-2
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DOI: https://doi.org/10.1038/s41591-024-03131-2
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