The University of Indonesia’s School of Public Health, the Eijkman Institute for Molecular Biology and the Jakarta administration conducted antibody tests on 4,919 people above the age of 1 from around 100 subdistricts of the capital’s five municipalities and the Thousand Islands regency from March 15 to 31.
The study found that 44.5 percent of participants had developed coronavirus antibodies. Some 81 percent of participants with antibodies had never been tested for Covid-19 and 63 percent had never experienced symptoms.
Jakarta, with a population of about 10.6 million people, had a cumulative confirmed case tally of 382,055 as of March 31.
Covid-19 cases are confirmed through PCR testing. If this pattern has held, it is possible that 4.7 million Jakarta residents have had the virus, with only 8.1 percent of cases having been recorded, the survey suggested.
“This is the most important bit, that most of the infected people that later formed the antibodies neither experienced symptoms nor were detected by the official tally,” University of Indonesia epidemiologist Pandu Riono, who was involved in the study, told The Jakarta Post on Tuesday.
“(From the survey) we can estimate how many Jakartans have had the coronavirus, but the testing conducted was not enough to detect them,” he added.
Jakarta has the highest rate of Covid-19 testing in Indonesia, higher than the World Health Organization standard of one test per 1,000 people per week.
Jakarta now conducts 20 tests per 1,000 people per week, up from 7 tests per 1,000 people per week in March.