SINGAPORE — An imported case who arrived from India earlier this month was "probably re-infected" when he was in his home country and had been infectious when he came back here, said the Ministry of Health (MOH) on Tuesday (21 April).
The 43-year-old Indian national then went on to infect his sister-in-law and her husband, both permanent residents here. The work pass holder and his two household contacts form a new cluster named after the woman's case number "62045".
The ministry did not mention whether they are infected with the new "double mutant" COVID-19 strain first discovered in India named B.1.617, which appears to be the main driving force behind a surge in new cases in the country.
The man had arrived from India on 2 April and was asymptomatic, said the MOH. His on-arrival swab was positive for COVID-19 and he was conveyed to a hospital.
"He was subsequently assessed to be a recovered case based on his high Ct value which indicated a low viral load, positive serology test result on 4 April, as well as negative pre-departure test taken on 31 March," said the MOH.
It added that the man was discharged from the hospital on 6 April, without the need for further isolation as he was deemed to have been shedding minute fragments of the virus RNA, which were no longer transmissible and infective to others.
However, on 17 April, as he had been identified as a close contact of his sister-in-law, he was again tested for COVID-19 and his test result came back positive.
"His serology test result is also positive. The Ct value of his polymerase chain reaction (PCR) test taken on 17 April was lower than his test done on 2 April, indicating a higher viral load this time," said the MOH.
"His antibody titres are also currently very high, suggesting that he was exposed to a new infection which boosted his antibody levels."
The MOH said that, in consultation with an expert panel which comprises infectious diseases and microbiology experts, it has assessed that he was likely to have been re-infected with COVID-19 recently.
"Similar imported cases suspected of re- infection will be isolated and undergo repeat COVID-19 PCR tests to monitor the trend of their viral loads, to ensure that such cases are detected promptly," it added.
This comes as the ministry announced earlier on Tuesday a slew of revised border measures, including stricter ones for travellers arriving from India, to take effect from 11.59pm on Thursday.
The US on the same day warned against travel to India, where authorities there had imposed tighter restrictions.
The MOH confirmed 14 new COVID-19 cases in Singapore on the same day, including one new case of locally transmitted infection who is a dormitory resident, taking the country's total case count to 60,865.
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