While re-infection is rare, the ministry, in consultation with an expert panel, has assessed that the clinical and laboratory evidence “suggests that this is a likely case of re-infection”.
In addition to his positive polymerase chain reaction (PCR) test results, the ministry said there was a corresponding marked increase in antibody titres compared to the period prior to the likely re-infection, “suggesting that he was exposed to a new infection which boosted his antibody levels”.
“The virus detected in his samples taken in January 2021 is also genetically distinct from that associated with the dormitories outbreak in 2020, suggesting that this is likely a different and new infection,” said the ministry in a statement late Saturday.
The expert panel comprises infectious diseases and microbiology experts from the National Centre for Infectious Diseases (NCID), Singapore General Hospital and the National Public Health Laboratory.
MOH noted that it will continue to closely monitor recovered Covid-19 cases to determine their post-infection immunity.
“So far, there is no indication that recovered workers in the dormitories have significant loss of post-infection immunity,” it said.
The ministry said, the worker, previously labelled as Case 2513, was identified from rostered monitoring testing conducted as part of its surveillance of recovered workers to monitor their post-infection immunity.
MOH said the case is a 28-year-old male Bangladesh national holding a Work Permit who resides in a dormitory located at 43 Tech Park Crescent.
He had been confirmed to have Covid-19 infection on April 12, 2020 and subsequently recovered, and consistently tested negative for Covid-19 infection from June 2020 onwards.
On Jan 25, 2021 however, his test result came back positive for Covid-19 infection, and he was isolated.
“Numerous repeat tests conducted subsequently were also positive for the virus,” said the ministry.
MOH said the worker who is currently warded at NCID, reported that he felt unwell on Jan 22 and 23, but is otherwise asymptomatic.
It added that all the identified close contacts of the case of whom all have tested negative for Covid-19 so far, have been isolated and placed on quarantine.