Oral Presentation 15th Lorne Infection and Immunity 2025

Levels and functionality of Pacific Islanders’ hybrid humoral immune response to BNT162b2 vaccination and delta/omicron infection: a cohort study in New Caledonia (#46)

Catherine Inizan 1 , Adrien Courtot 2 , Chloé Sturmach 3 , Anne-Fleur Griffon 1 , Antoine Biron 4 , Timothée Bruel 5 , Vincent Enouf 3 , Thibaut Demaneuf 6 , Sandie Munier 7 , Olivier Schwartz 8 , Ann-Claire Gourinat 4 , Georges Médevielle 2 , Marc Jouan 1 , Sylvie van der Werf 7 , Yoann Madec 9 , Valérie Albert-Dunais 10 , Myrielle Dupont-Rouzeyrol 1
  1. Institut Pasteur De Nouvelle Calédonie Pasteur Network, Noumea, New Caledonia
  2. Provincial Office for Health and Social Action of the South Province (Direction Provinciale de l’Action Sanitaire et Sociale en Province Sud), Nouméa, New Caledonia
  3. National Reference Center for Respiratory Viruses, Institut Pasteur, Paris, France
  4. New Caledonia Territorial Hospital, Dumbéa-sur-Mer, New Caledonia
  5. Antiviral Activities of Antibodies Group, Institut Pasteur, Paris, France
  6. Social and Sanitary Agency of New Caledonia , Nouméa, New Caledonia
  7. Molecular Genetics of RNA Viruses Unit, Institut Pasteur, Paris, France
  8. Virus and Immunity Unit, Institut Pasteur, Paris, France
  9. Epidemiology of Emerging Diseases, Institut Pasteur, Paris, France
  10. New Caledonia Specialized Hospital, Nouméa, New Caledonia

Background

Pacific Islanders are underrepresented in vaccine efficacy trials. Few studies describe their immune response to COVID-19 vaccination. Yet, this characterization is crucial to re-enforce vaccination strategies adapted to Pacific Islanders singularities.

Methods and Findings

We evaluated the humoral immune response of 585 adults, self-declaring as Melanesians, Europeans, Polynesians or belonging to other communities, to the Pfizer BNT162b2 vaccine. Anti-spike and anti-nucleoprotein IgG levels, and their capacity to neutralize SARS-CoV-2 variants and to mediate Antibody-Dependent Cellular Cytotoxicity (ADCC) were assessed across communities at one and three months post-second dose or one and six months post-third dose. All sera tested contained anti-spike antibodies and 61.3% contained anti-nucleoprotein antibodies, evidencing mostly a hybrid immunity resulting from vaccination and SARS-CoV-2 infection. At one-month post-immunization, the four ethnic communities exhibited no significant differences in their anti-spike IgG levels (p value=0.17, in an univariate linear regression model), in their capacity to mediate omicron neutralization (p value=0.59 and 0.60, in an univariate logistic regression model at one-month after the second and third dose, respectively) and in their capacity to mediate ADCC (p value = 0.069 in a multivariate linear regression model), regardless of the infection status. Anti-spike IgG levels and functionalities of the hybrid humoral immune response remained equivalent across the four ethnic communities during follow-up and at six months post-third dose.

Conclusions

Our study evidenced Pacific Islander’s robust humoral immune response to Pfizer BNT162b2 vaccine, which is pivotal to re-enforce vaccination deployment in a population at risk for severe COVID-19 (clinicaltrials.gov: NCT05135585).