SINGAPORE - Tan Tock Seng Hospital (TTSH) said on Tuesday (July 14) that its laboratory mislabelled testing samples which led to a student being wrongly diagnosed with Covid-19.

The Secondary 1 female student from Jurong West Secondary School was reported last Friday to have tested positive for coronavirus. She was swabbed because she had been in contact with a schoolmate, a 13-year-old boy, who was previously confirmed to be infected.

Labelling error

In a statement on Tuesday, the Ministry of Health (MOH) said the female student, known as Case 45655, was reported to be infected based on the erroneous test results submitted by the laboratory. The laboratory had mislabelled a swab sample from a Covid-19 positive individual as belonging to Case 45655 without properly verifying the patient identifiers on the specimen tubes.

"Consequently, Case 45655 was recorded as being positive for Covid-19, and was reported to MOH as such."

The error was discovered upon re-testing of the student and MOH was informed of the error on July 13.

The mislabelled positive sample belongs to a migrant worker who had been isolated since his swab, and had not been in contact with any other individuals. He is currently well.

The ministry said that it takes a serious view of this error.

"We are investigating this matter, and will take appropriate actions against the laboratory if it is found to be in breach of protocols. In the meantime, the laboratory has reviewed and tightened its processes to prevent a recurrence of the error," it added.

The MOH said the female student had been isolated and had not come into contact with any other Covid-19 patients and is, therefore, not at risk of infection from other patients in the hospital.

The girl had been serving a home quarantine order by MOH since July 6, as she was a close contact of her school mate who was infected earlier. She will continue to be in quarantine.

The MOH has informed MOE, and rescinded the quarantine orders of the close contacts who had previously been placed on quarantine.

It was reported previously that six students and four staff members were to be placed on quarantine due to the girl's case.

The latest findings mean there is no second confirmed case in Jurong West Secondary or student-to-student transmission in the school, said Ms Liew Wei Li, Ministry of Education's (MOE) director of schools.

In a Facebook post on Tuesday, Education Minister Ong Ye Kung said: "On 10 July, all of us at MOE were dismayed when we learnt that at Jurong West Secondary School, a student who caught the Covid-19 virus at home, has infected another classmate.

"This would have been our first recorded Covid-19 infection in school, despite all our precautionary measures."

He added: "To our relief, TTSH and MOH have clarified that it was a case of erroneous reporting by the testing laboratory."

TTSH apologises

In a separate statement, TTSH apologised for the mislabelling.

It said the student is well and has been discharged.

The other patient, who was in isolation, has been admitted to National Centre for Infectious Diseases (NCID) and remains stable.

TTSH said the original test was undertaken by its laboratory. Subsequently, the student was admitted to the National University Hospital and was tested twice, and found to be negative on both occasions.

The TTSH laboratory repeated a polymerase chain reaction test on the original sample and the result was negative.

Both patients have been informed of the mislabelling incident, said the hospital, adding that it has apologised for the anxiety caused.

"We are sorry for the mistake and sincerely regret the inconvenience caused to our patients and the school," it said.

"We have audited our laboratory testing for Covid-19 for that period and no other mislabelling was discovered. We have also put in place additional checks to prevent such an incident from occurring again."

Measures in school

Jurong West Secondary had placed all Secondary 1 students on home-based learning last Wednesday and Thursday.

"As there are a number of teachers from the school serving home quarantine order, the home-based learning period for Secondary 1 students will continue till July 17 so that students can continue to be taught by their own teachers. Classes for all other levels will continue in school as per normal," said MOE's Ms Liew.

She said that schools have implemented comprehensive safe management measures to ensure the safety of students and staff, and minimise the risk of transmission.

This includes spaced-out seating in classrooms to ensure safe distancing, the wearing of face masks, staggered arrival, dismissal and recess timings and minimising intermingling across classes and levels.

"Students should also head directly home after school," said Ms Liew. "It is also equally important that each of us exercises personal responsibility. We would like to remind all parents, staff and students that if a student or any adult family member is unwell, the student should not go to school."

Minister Ong said that school attendance rate at Jurong West Secondary has remained at more than 90 per cent.

"Students, parents and teachers have adapted well to all our precautionary measures - calmly and with resolve to minimise disruptions to learning," he said.