Defining the COVID-19 Immunity Denominator in the Mekong: a Cross-Sectional Seroprevalence Study of SARS-CoV-2 in HealthyVolunteers

Defining the COVID-19 Immunity Denominator in the Mekong: a Cross-Sectional Seroprevalence Study of SARS-CoV-2 in Healthy Volunteers

Background:

In early 2020, many people thought Cambodia would have a serious COVID-19 outbreak due to the high number of Chinese travelers going to Cambodia. But as of June 14, 2020, only 128 cases of COVID-19 have been identified in the country. Many of these cases have been from people who had traveled in Europe. Researchers want to do antibody tests on blood from a sampling of people in Phnom Penh to learn the infection risks for people in the greater Phnom Penh area.

Objective:

To estimate the level of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the blood of people living in Phnom Penh, Cambodia.

Eligibility:

Healthy males and females age 18-65 living in Phnom Penh since January 2020.

Design:

A mobile unit will travel to schools, shopping areas, parks, and pagodas around Phnom Penh.

Participants will be screened with questions about their age and where they live. They will have blood taken via fingerstick. About 80 uL of blood will be taken. It will be tested for SARS-CoV-2. This visit will take about 30 minutes.

If the test result is positive, participants will be contacted by phone. They will be asked to have a second blood draw. This time, 20 mL of blood will be taken. They can have this visit at their home or in a clinic. This visit will take about 30 minutes.

If a participant has an adverse event, the mobile units and at-home units will have the tools needed to aid the participant. If needed, the participant will be sent to a nearby clinic.

Study Overview

• Status: Withdrawn
• Conditions: Healthy Volunteers

Detailed Description

This is a cross-sectional study performed annually over 3 years to procure blood samples by fingerstick from healthy individuals living in the Phnom Penh area to evaluate seroprevalence to SARS-CoV-2. A mobile unit will move between various markets, schools, hospitals, clinics, parks, and other public places with local authority permissions. Participants with a positive result on the screening SARS-CoV-2 ELISA will be contacted via telephone (since there is not reliable mail in Cambodia) and invited to undergo an additional blood draw via venipuncture during a home visit by the mobile team within 180 days of the initial sample collection. This visit may also be conducted by CCDC/CNM/MOH study staff at a local clinic. Up to 10 of their adult household contacts will be invited to enroll and screen at this time via fingerstick for SARS-CoV-2 ELISA as part of an enriched sampling scheme to boost the probability of identifying SARSCoV- 2 immune individuals; those with positive results will be invited to undergo follow-up venipuncture as described above. Venipuncture samples will be used to study the immune responses of Cambodians to the novel coronavirus.

• Study Type: Observational

Contacts and Locations

Study Locations

• Cambodia
  • Phnom Penh, Cambodia
    • Cambodian Center for Communicable Disease (CCDC), Ministry of Health (MOH)
  • Phnom Penh, Cambodia
    • National Malaria Center (CNM), Ministry of Health (MOH)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Advertising and recruitment in this province will mainly be via word of mouth using health staff and the local village chiefs to communicate to the general public when and where the mobile unit will be sampling. Large signs and banners will be made to hang wherever the mobile unit set up in the designated area. We anticipate having to screen no more than 2,500 individuals per year to enroll our target of 2,000 participants per year over the next 3 years. We have no pre-set male:female ratios or age structures. We do plan to sample many different small clusters from the majority of Phnom Penh s administrative districts. Up to 200 household contacts may also be enrolled each year, bringing the overall total to 2,200 individuals enrolled per year. To account for screen failures, our total accrual ceiling over 3 years is 8,100.

Description

• INCLUSION CRITERIA:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

1. Stated willingness to comply with all study procedures and availability for the duration of the study.
2. Male or female, aged 18 - 65 years of age.
3. Residing in Phnom Penh since January 1, 2020.
4. Ability to provide consent.

EXCLUSION CRITERIA:

An individual who meets any of the following criteria will be excluded from participation in this study:

1. Any acute illness requiring a visit to a clinic or hospital on the same day as study enrollment.
2. Any underlying, chronic, or current medical condition that, in the opinion of the investigator, would interfere with participation in the study (e.g., inability or great difficulty in drawing blood).

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Healthy volunteers; Any adult aged 18 to 65 years of age living in Phnom Penh that is sufficiently healthy and willing to undergo fingerstick by the mobile unit for SARS-CoV-2 ELISA assays.
Household contacts; Adult relatives of the healthy volunteers.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Presence or absence of SARSCoV-2 immunoglobulin in participant sera by ELISA optical density change.	Using convenience sampling at randomized points across Phnom Penh, ELISAs to the SARS-CoV-2 full-length spike and ribonucleocapsid protein (RNP) antigens will be used as these are the most sensitive and specific to be interpreted in the setting of any background noise introduced by Cambodian sera, and because they are less expensive and amenable to high-throughput processing.	Enrollment Day 1 (and Study Visit 2 if applicable)

Collaborators and Investigators

• Sponsor: National Institute of Allergy and Infectious Diseases (NIAID)

Publications and helpful links

General Publications

• Lang Z, Reiczigel J. Confidence limits for prevalence of disease adjusted for estimated sensitivity and specificity. Prev Vet Med. 2014 Jan 1;113(1):13-22. doi: 10.1016/j.prevetmed.2013.09.015.

Study record dates

Study Major Dates

• Study Start (ACTUAL): September 24, 2021
• Primary Completion (ACTUAL): September 24, 2021
• Study Completion (ACTUAL): September 30, 2021

Study Registration Dates

• First Submitted: October 17, 2020
• First Submitted That Met QC Criteria: October 17, 2020
• First Posted (ACTUAL): October 20, 2020

Study Record Updates

• Last Update Posted (ACTUAL): October 4, 2021
• Last Update Submitted That Met QC Criteria: October 1, 2021
• Last Verified: October 1, 2021

More Information

Terms related to this study

• Keywords: ELISA; Mobile Units; SARS-CoV-2 Immunoglobulin-Positive; Antibody-Based Tests; Phnom Penh
• Other Study ID Numbers: 10000083; 000083-I