Evidence map›Paper›PMID 42032159›Full record

ArticleScientific reports2026

Long-term kinetics of anti-RBD IgG antibodies 16 months after COVID-19 vaccination in Morocco: a longitudinal cohort study.

Islam Abbadi, M'hammed Sarih, Hind Majidi, Soad Redwane, Serge Batcho, Karima Abounouh, Safaa Aqillouch, Oumaima Bouddahab, Soufiane Hilmi, Abdelhakim Ainahi and 5 more

Abstract read
In one paragraph

Article in Scientific reports, 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

15 authors.

Islam AbbadiVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco.
M'hammed SarihService de Parasitologie et des Maladies Vectorielles, Institut Pasteur du Maroc, Casablanca, Morocco.
Hind MajidiMinistry of Health and Social Protection, Rabat, Morocco.
Soad RedwaneDirection Régionale de la santé Casablanca-Settat, Observatoire régional de santé, Casablanca, Morocco.
Serge BatchoAfrica Centres for Disease Control and Prevention (Africa CDC), African Union, Addis Ababa, Ethiopia.
Karima AbounouhVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco.
Safaa AqillouchVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco.
Oumaima BouddahabVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco.
Soufiane HilmiVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco.
Abdelhakim AinahiHormonology and Tumor Markers Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco.
Raji TajudeenAfrica Centres for Disease Control and Prevention (Africa CDC), African Union, Addis Ababa, Ethiopia.
Mosoka Papa FallahAfrica Centres for Disease Control and Prevention (Africa CDC), African Union, Addis Ababa, Ethiopia.
Jean KaseyaAfrica Centres for Disease Control and Prevention (Africa CDC), African Union, Addis Ababa, Ethiopia.
Abderrahmane MaaroufiVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco.
Sayeh EzzikouriVirology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco. sayeh.ezzikouri@pasteur.ma.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Understanding the long-term durability of vaccine-induced immunity is crucial for shaping public health strategy. This study aimed to evaluate the 16-month kinetics of anti-receptor-binding domain (RBD) IgG antibodies following COVID-19 vaccination in Morocco. In this longitudinal cohort study, 2,546 blood samples were collected from 1,273 participants across the Casablanca-Settat region at six and sixteen months after the last vaccine dose. Participants had received homologous or heterologous regimens with the BNT162b2, ChAdOx1‑S, or BBIBP‑CorV vaccines. Anti‑RBD IgG levels were quantified using a chemiluminescent microparticle immunoassay. Multivariable linear mixed‑effects modeling was used to evaluate associations with age, sex, vaccine platform, number of doses, prior infection, and comorbidity status. Antibody levels declined significantly between six and sixteen months among participants who received only two doses (β = -0.072, 95% CI - 0.088 to - 0.056; p < 0.001). Receipt of a third dose was independently associated with higher antibody levels (β = 0.180, 95% CI 0.070-0.290; p = 0.001), with no significant interaction between dose number and time (p = 0.717). Prior SARS‑CoV‑2 infection was associated with higher antibody levels in unadjusted analyses but was not independently associated with antibody magnitude after multivariable adjustment. Increasing age was associated with higher antibody levels (β = 0.008 per year; p < 0.001), and no significant interaction between age and time was observed (p = 0.338), indicating comparable antibody decay across age groups. A trend toward higher antibody levels in females compared with males was observed but did not reach conventional statistical significance (p = 0.052). Anti‑RBD IgG antibodies decline over time following primary vaccination but remain detectable at 16 months. Booster vaccination is independently associated with higher antibody levels. Antibody decay kinetics appear broadly comparable across subgroups based on age, sex, and dose number. These findings support continued booster vaccination strategies to sustain humoral immunity.

Indexed as

Antibodies, ViralCOVID-19COVID-19 VaccinesImmunoglobulin GSARS-CoV-2Spike Glycoprotein, CoronavirusAdultAgedBNT162 VaccineFemaleHumansKineticsLongitudinal StudiesMaleMiddle AgedMoroccoAntibodies, ViralBNT162 VaccineCOVID-19 VaccinesImmunoglobulin GSpike Glycoprotein, CoronavirusAntibody kineticsAnti-RBD IgGBooster dosesMoroccoSARS-CoV-2

Identifiers

PMID42032159
PMCPMC13275918

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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.