Evidence map›Paper›PMID 41968603›Full record

ArticleJournal of immunology research2026

C3d Complement Activation and Antibody Immunity in Convalescent COVID-19: Insights From Adults and Children.

Ratna Wijaya, Jordan Stoddart, Anurag Adhikari, Arunasingam Abayasingam, Adam W Bartlett, William Rawlinson, Michael M Mina, Jeffrey J Post, Bernard Hudson, Nicky Gilroy and 7 more

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Journal of immunology research, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

17 authors.

Ratna WijayaThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0002-1445-8341
Jordan StoddartThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.
Anurag AdhikariDepartment of Infection and Immunology, Kathmandu Research Institute for Biological Sciences, Lalitpur, Nepal, kribs.org.np.ORCID https://orcid.org/0000-0003-3168-0558
Arunasingam AbayasingamThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0002-9406-3058
Adam W BartlettThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0002-7532-9316
William RawlinsonSchool of Biomedical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0003-0988-7827
Michael M MinaNorthern Beaches Hospital, Sydney, New South Wales, Australia, northernbeacheshospital.com.au.ORCID https://orcid.org/0000-0001-8644-5702
Jeffrey J PostDepartment of Infectious Diseases, Prince of Wales Hospital, Sydney, New South Wales, Australia, princeofwalesprivatehospital.com.au.ORCID https://orcid.org/0000-0003-1475-9272
Bernard HudsonRoyal North Shore Hospital, Sydney, New South Wales, Australia, nsw.gov.au.ORCID https://orcid.org/0000-0002-8582-058X
Nicky GilroyWestmead Hospital, Sydney, New South Wales, Australia, nsw.gov.au.
Pam KonecnySchool of Clinical Medicine, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0003-0166-2287
Golo AhlenstielBlacktown Clinical School, School of Medicine, Western Sydney University, Blacktown, New South Wales, Australia, westernsydney.edu.au.ORCID https://orcid.org/0000-0003-0026-1457
Marianne MartinelloThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0001-9444-0186
Andrew R LloydThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0001-6277-8887
Nicodemus TedlaSchool of Biomedical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0002-8226-8064
Rowena A BullThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0002-9844-3744
Melanie R WalkerThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, unsw.edu.au.ORCID https://orcid.org/0000-0002-9731-9880

Funding

APEC-Australia Women in Research FellowshipCouncil of Australasian University LibrariansSnow Medical FoundationUniversity of New South Wales
6 · The paper itself

Abstract

Following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the complement pathway becomes activated, generating the stable split product C3d. Although C3d can modulate B cell responses through complement receptor 2 (CR2) in experimental systems, it remains unclear how circulating C3d relates to antibody responses after SARS-CoV-2 infection in humans. Here, we examined plasma C3d levels and their associations with SARS-CoV-2-specific antibody responses and clinical characteristics in convalescent adults and children. In adults, older age, male sex, and a history of severe COVID-19 were independently associated with higher C3d levels. C3d concentrations positively correlated with receptor-binding domain (RBD)-specific antibody-dependent cellular phagocytosis (ADCP), neutralizing antibody (nAb) titer, and anti-spike IgM, IgG, IgG1, and IgG3 levels. In children, C3d levels were significantly lower than in adults and correlated with anti-spike and anti-RBD IgG titers. These findings demonstrate that systemic complement activation, reflected by circulating C3d, is positively associated with SARS-CoV-2 antibody responses in both age groups. As this cross-sectional study cannot determine causality, further mechanistic and longitudinal studies are needed to define the role, if any, of C3d in shaping adaptive immunity to SARS-CoV-2.

Indexed as

Antibodies, ViralComplement ActivationComplement C3dCOVID-19SARS-CoV-2AdolescentAdultAgedAge FactorsAntibodies, NeutralizingChildChild, PreschoolConvalescenceCross-Sectional StudiesFemaleHumansAntibodies, NeutralizingAntibodies, ViralComplement C3dImmunoglobulin GImmunoglobulin MSpike Glycoprotein, Coronavirusspike protein, SARS-CoV-2

Identifiers

PMID41968603
PMCPMC13581050

What OpenQuestion holds

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.