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Background

Since March 2020, the number of COVID-19 cases in Indonesia has been growing exponentially. As of 28 June 2021, there have been 2,135,998 confirmed cases of COVID-19 in Indonesia, including 57,561 deaths. The cases are distributed unevenly in 34 provinces in Indonesia, with DKI Jakarta, West Java, Central Java, East Java, East Kalimantan, Riau, South Sulawesi, DI Yogyakarta, Banten, and West Sumatera being the top 10 provinces with the highest number of confirmed cases.
The true burden of COVID-19 in Indonesia remains unclear. Between 6-12 July 2021, the national number of COVID-19 molecular tests ranged from 123,317 – 145,294 tests per day, with a daily positivity rate ranging from 22.8 – 32%. Our country witnessed a record-breaking 56,757 new daily cases on July 15, 2021. The high positivity rate in Indonesia suggests that many infections remain undetected. Even though there is an increase in collective testing capacity among Indonesian laboratories throughout the pandemic, the use of molecular detection of SARS-CoV-2 in Indonesia is more targeted at moderately or severely ill patients, for contact tracing purposes, or one of the travel requirements. The PCR test is also costly to perform and there is a trend to move towards antigen rapid diagnostic tests (Ag RDT) for screening and rapid detection of SARS-CoV-2. Therefore, the number of cases based on molecular assays may not be representative of the actual burden of SARS-CoV-2 infection.

A population-based seroprevalence survey is useful in measuring the extent of SARS-CoV-2 infection as it can identify individuals who were infected but might not have received PCR testing due to mild or asymptomatic disease. Seroprevalence surveys are also useful in measuring overall population immunity, whether achieved naturally or via vaccination. This is the reason that through INSPIRASI (Improving Quality of Disease Preparedness, Surveillance & Response in Indonesia), we would like to conduct a COVID-19 serosurvey study in several provinces in Indonesia. Multiple serosurvey studies are being conducted in the country. This project, which targets populations in four provinces in Indonesia, would contribute to discovering the burden of COVID-19 in Indonesia. The serosurvey will be conducted in Banten, West Java, East Java, and Sulawesi Selatan, which are provinces with very high numbers of COVID-19 cases and have never been assessed with a population-based COVID-19 serosurvey.

Each province in Indonesia has a different laboratory testing capacity. A report by WHO on July 7, 2021, mentioned that there are only 5 provinces in Indonesia that meet the WHO standard of testing 1 person per 1,000 population size. Those provinces were DKI Jakarta, DI Yogyakarta, West Sumatra, West Papua, and Riau. By assessing seroprevalence in our targeted locations, we can provide an estimated number of laboratory-diagnosed infections to the total number of infections in each province. This way, we can also predict the extent of population-level antibody response to SARS-CoV2 in each province.

Data on demographic factors, including existing comorbidities and disease history would also be collected and would give us information on individual risk factors associated with seropositivity. Knowledge, attitudes, and practices on COVID-19 prevention measures, associated risks, and vaccine acceptance will also be evaluated. As of 12 March 2021, a total of 3,696,059 people has received the first dose of the COVID-19 vaccine in Indonesia. That number still falls far behind the targeted number of vaccinated people in Indonesia, which is 181,554,465 people (about 2% of the target). Among the 2%, only 1,295,615 people have also received the second dose of the Sinovac® COVID-19 vaccine. As the vaccination program is still ongoing, vaccine acceptance amongst the general population will be valuable information to collect.

This project would also strengthen technical and analytical capabilities of Indonesian government laboratories to perform immune response characterization by using multiplex, microsphere-based immunoassays through the provision of laboratory equipment and a series of training. This will be beneficial not only for COVID-19 diagnostics but also to diagnose and study many other diseases in the future.

Objectives

1. Primary Objective
   This project is intended to assess the prevalence of SARS-CoV-2 infection among targeted populations in Banten, West Java, East Java, and Sulawesi Selatan
2. Secondary Objectives
   
   1. To identify individual risk factors, especially comorbidities, that are associated with SARS-CoV-2 infection in the studied populations
   2. To estimate the ratio of laboratory diagnosed infections to the total number of infections in each province.
   3. To estimate the extent of population-level antibody response to SARS-CoV2 in each province.
   4. To increase laboratory diagnosis capacity in Indonesia (specifically BBTKLPP Yogyakarta) to perform serodiagnosis of COVID-19 using multiplex microsphere-based immunoassay.
   5. To measure the knowledge, attitudes, and practices (KAP) in the target population regarding knowledge regarding COVID-19 associated risks, preventive measures, and vaccine acceptance.[GG(1]

Study Locations

This serosurvey project targets populations in several provinces of Indonesia; Banten, West Java, East Java, and South Sulawesi (Figure 1). The province selection was done in consultation with the Ministry of Health of the Republic of Indonesia[ABH2] . No COVID-19 serosurveys have been done in the selected provinces. Those provinces are also among the top 10 provinces with the highest number of COVID-19 cases in Indonesia. Following a Laboratory analysis will be conducted at Balai Besar Teknik Kesehatan Lingkungan dan Pengendalian Penyakit (BBTKLPP) Yogyakarta, BTKLPP Makassar and the Integrated Research Laboratory, Faculty of Medicine, Public Health, and Nursing Universitas Gadjah Mada.
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[GG(1]Level 2- Suggest that the purpose of this objective be listed clarify if this data is for documenting historical reasons for vaccination/non-vaccination, or data to direct demand creation activities.
[ABH2]L3 - Please note that the survey will only be representative of these provinces.