Cohort Study of Arbovirus and Other Emerging Virus Infections in Fiji: AEVI-Fiji Cohort.

NCT07229677 | Recruiting

• 2 other identifiers: FNUHHREC 017.25FNHRERC 08/25
• Study Type: observational
• Target: 910
• Locations: 1 country
• Sites: 1

Brief Summary

Background: Fiji, an archipelago in the South Pacific comprising 332 islands distributed among 4 health administrative divisions (Central, Western, Eastern, Northern), is particularly vulnerable to the (re-)emergence of arboviruses and respiratory viruses due to its sub-tropical climate, the presence of several mosquito vector species, and connections with many countries in the Pacific, Asia and North America. Over the past decades, the epidemiological landscape of arboviruses has shifted from the sequential circulation of each of the four dengue virus (DENV) serotypes to the emergence of Zika virus (ZIKV) and chikungunya virus (CHIKV), concomitantly to the concurrent circulation of multiple DENV serotypes. The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2020 significantly challenged Fiji's healthcare system, with the Delta variant alone accounting for approximately 700 deaths, while other respiratory viruses, such as influenza A and B, cause seasonal outbreaks. Despite these threats, comprehensive and up-to-date seroprevalence data remain scarce, limiting the capacity to inform and adapt public health policies. Methods: The cohort study of Arbovirus and other Emerging Virus Infections in Fiji (AEVI-Fiji cohort study) aims to estimate the prevalence of several arboviruses and respiratory viruses, track the evolution of individual immunity, and analyse transmission dynamics of these viruses within the Fijian population. This longitudinal study will span 38 months and will include about 900 willing participants aged six years and older, recruited from at least 210 households randomly selected across the Central Division. Four visits will be conducted 12 months apart in each household. During each visit, participants will complete a questionnaire capturing their demographic characteristics and history of infections with major arboviruses and respiratory viruses and will provide a blood sample for serological analysis. During the whole study period, participants with a suspected acute infection by an arbovirus or respiratory virus will be screened. Discussion: For the first time in Fiji, the AEVI-Fiji cohort study will generate longitudinal data to explore the determinants of both arbovirus and respiratory virus infections. The findings are expected to guide targeted public health strategies and enhance preparedness for future infectious disease threats in Fiji and the broader Oceania region.

Conditions

Arbovirus Infections; Respiratory Infection Virus

Keywords

Seroprevalence; Longitudinal cohort; Respiratory viruses; Arboviruses; Fiji Islands

Outcome Measures

Primary Outcomes (1)

• Level of herd immunity for arboviruses and respiratory viruses by conducting a seroprevalence survey among households including both children and adults In Central division of Fiji

  Proportion of participants with Immunoglobulin type G (IgG) antibodies, detected in blood samples : IgG antibodies specific to a panel of arboviruses (including the four DENV serotypes, ZIKV, CHIKV, Ross River virus \[RRV\], yellow fever virus \[YFV\], Japanese encephalitis virus \[JEV\], West Nile virus \[WNV\]) and respiratory viruses (including influenza viruses A and B, SARS-CoV-2), as well as any major emerging pathogen (pathogen X) will be detected, using a multiplex microsphere immunoassay (MIA). Additionally, seroneutralisation tests will be performed to detect and quantify neutralising antibodies against the same panel of viruses. The IgG and neutralising antibody results for each virus will be combined to determine overall immune response (positive/negative) for the targeted viruses.

  From enrollment to the end of the first inclusion visit (V1) at month 12

Secondary Outcomes (2)

• Evolution of individual memory immunity for arboviruses and respiratory viruses by performing serological monitoring of the study participants over a period of 38 months

  From enrollment to the end of the last visit (V4) at month 38

• Systematic screening and sequencing of acute infections of the study participants over a period of 38 months

  From enrollment to the end of the last visit (V4) at month 38

Study Arms (1)

Households members representative of the Fijian population (6 years and older)

The study sample comprises randomly selected households from 30 Enumeration Areas (EAs) within the Central Division, selected in proportion to population size to ensure representativeness of the Fijian population. Both urban and rural settings are included. All individuals aged 6 years and above residing for more than 6 months in the selected households are invited to participate in the study.

Eligibility Criteria

• Age: 6 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

The study will specifically target residents of the Central Division of Fiji, which accounts for approximately 42.7% of Fiji's total population. Most inhabitants are located within the Nausori-Lami corridor, a region characterized by a mix of urban, peri-urban, and rural areas. The Central Division is also notable for its ethnic diversity, comprising Indigenous iTaukei, Indo-Fijians, and other minority groups, making it representative of Fiji's broader demographic composition.

You may qualify if:

• Individuals aged 6 years and older who reside in the Central Division of Fiji
• Have lived in the selected household for at least six months at the time of enrollment

You may not qualify if:

• Pregnant women;
• Women in labor, or breastfeeding mothers;
• Individuals deprived of liberty by judicial or administrative decision;
• Individuals under psychiatric care or admitted to a health or social care facility for purposes other than participation in the study;
• Adults under legal protection or unable to provide informed consent;
• Homeless individuals;
• Individuals with severe disabilities preventing mobility;
• Individuals unable to understand or complete the study questionnaire

Sponsors & Collaborators

• Fiji National University: lead
• Institut Louis Malardé: collaborator
• Institut Pasteur: collaborator
• Institut Hospitalo-Universitaire Méditerranée Infection: collaborator
• Ministry of Health, Fiji: collaborator
• London School of Hygiene and Tropical Medicine: collaborator

Study Sites (1)

Fiji National University

Suva, Central, Fiji

RECRUITING

Biospecimen

Retention: SAMPLES WITH DNA

Blood samples will be collected by trained phlebotomists at each scheduled visit (V1 to V4) as follows: * Participants aged 12 years and older: whole blood will be collected; serum will be extracted and stored at -80°C. * Participants aged 6-11 years: capillary blood will be collected on filter paper, dried, and stored at -4°C. Each participant will be assigned a unique Participant ID to ensure pseudonymization. The ID consists of a 4-digit participant number combined with a 7-character visit code (e.g., AEVI-FV1 to AEVI-FV4) to differentiate study visits.

MeSH Terms

Conditions

Arbovirus Infections

Condition Hierarchy (Ancestors)

Vector Borne Diseases; Infections; Virus Diseases

Study Officials

• Donald Wilson, MBBS, PhD-Epidemiology

  Fiji National University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Isireli Koroituku, Masters Infectious Diseases

CONTACT

+679 9090729; isireli.koroituku@fnu.ac.fj

Ahmed Abdouni, PhD, MPH

CONTACT

+689 89527294; aabdouni@ilm.pf

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 13, 2025
• First Posted: November 17, 2025
• Study Start: October 23, 2025
• Primary Completion: December 31, 2025
• Study Completion (Estimated): December 31, 2028
• Last Updated: December 1, 2025

Record last verified: 2025-11

Locations

FI (1)