While the sample size is small it is believed to be a reliable indicator of a low infection rate among the 51 million people of a country held up as a coronavirus mitigation success story.
"The results indicate that each citizen has taken an active participation in tough social distancing," Kwon Jun-wook, the deputy director of the Korea Centers for Disease and Prevention (KCDC), told a briefing.
South Korea at one time had the most serious outbreak of the coronavirus outside China. It has had 13,293 cases and 287 deaths and has won praise for handling the pandemic without a full lockdown of its economy.
It has credited its success to widespread testing and strict social distancing.
Antibody, or serology, tests show whether a person has been exposed to the virus.
Out of 1,555 people tested nationwide between April 21 and June 19, none showed antibodies. One person was found with neutralizing antibodies from another sample of 1,500 people tested in late May in the capital, Seoul, the KCDC said.
Similar testing has shown rates ranging from 0.1% in Tokyo to 17% in London and 5% in Spain, it said.
The KCDC plans to expand testing to 3,300 people every two months and include regions hard hit by the virus, such as Daegu city, which had South Korea's biggest outbreak.
It was hoped the survey would offer insight into the level of herd immunity and asymptomatic infections, the KCDC said.Despite its success, South Korea is battling small but persistent clusters of infections with 50 new cases reported on Wednesday.