The Difference between Linked cases and cases under quarantined explained.

Recent reports by MOH has raised some eyebrows.

A typical report is as follow

Singapore reported 22 locally transmitted COVID-19 cases as of noon on Sunday (May 23), including 21 in the community and one who resides in a dormitory. 

Nineteen infections are linked to previous cases, while two community cases are currently unlinked. Among them, 12 cases had been placed on quarantine earlier.

This implied that out of the 19 linked cases, 7 have not been on quarantine. The understanding is that linked cases are usually picked out during quarantine, thus a mismatch in the numbers puzzle.

Using the same example ( May 23 report), we understand that the linked cases that were not quarantined were detected through surveillance. The link in these cases are PLACES and not PEOPLE. It is rather odd to link to places like a mall since it is a rather large location instead of a specific store. Nonetheless, the mystery is solved.

The linked cases without quarantine for May 23 as follows : 

JEM/ Westgate cluster

Detected through surveillance:

Case 63597 is a 39 year-old female Malaysia national who is employed by Eng Leng Contractors Pte Ltd as a cleaner at Westgate shopping mall. She is asymptomatic, and was detected when she was tested for COVID-19 on 21 May as part of our testing operations for those who worked in or visited JEM and Westgate. Her test result came back positive for COVID-19 infection on 22 May. She has tested preliminarily positive for the B.1.617 variant, and is pending further confirmatory tests. Her serology test result is pending.

Case 63600 is a 59 year-old male Singaporean who works as a music teacher at Yamaha Music School. He developed a fever on 16 May but did not seek medical treatment until 21 May when he went to a GP clinic, and was tested for COVID-19. His antigen rapid test (ART) came back positive on the same day, and he was immediately isolated. A polymerase chain reaction (PCR) test administered on the same day came back positive for COVID-19 infection. His serology test result is negative.

Case 63606 is a 31 year-old male India national who works as a delivery truck driver at YHI Corporation Pte Ltd. He is asymptomatic, and was detected when he was tested for COVID-19 on 21 May as part of our testing operations for those who worked in or visited JEM and Westgate. His test result came back positive for COVID-19 infection on 22 May. His serology test result is pending.

Case 63607 is a 44 year-old male India national who works at BlackRock Advisors Singapore Pte Ltd. He is asymptomatic, and was detected when he was tested for COVID-19 on 21 May as part of our testing operations for those who worked in or visited JEM and Westgate. His test result came back positive for COVID-19 infection on 22 May. He has tested preliminarily positive for the B.1.617 variant, and is pending further confirmatory tests. His serology test result is pending.

Marina Bay Sands Casino dealer cluster

Detected through surveillance:

Case 63610 is a 32 year-old female Singapore Permanent Resident who works as a hairdresser at 98 Hair House Pte Ltd, and was last at work on 17 May. She developed a fever, cough and sore throat on 19 May, and sought medical treatment at a GP clinic on the same day, where she was tested for COVID-19. Her test result came back positive for COVID-19 infection on 22 May. Her serology test result is pending.

McDonald’s delivery riders cluster

Detected through surveillance:

Case 63603 is a 31 year-old male China national who works as a delivery rider for McDonald’s (Pasir Ris Elias Community Club). He is a workplace contact of Cases 63535[6] and 63569[7], and was placed on Leave of Absence by his employer on 20 May. He was tested for COVID-19 on 21 May, and was placed on quarantine on the same day. He developed chills that night but did not report his symptom. On 22 May, he developed a cough and fatigue. His test result came back positive for COVID-19 infection on 22 May. His serology test result is negative.

Case 63624 is a 27 year-old male Malaysia national who works as a delivery rider for McDonald’s (Pasir Ris Elias Community Club). He is a workplace contact of Cases 63535 and 63569. He developed a headache and fatigue on 18 May. He was placed on Leave of Absence by his employer on 21 May and tested for COVID-19 on the same day. He was placed on quarantine on 21 May, but did not report his symptoms. He developed a cough on 22 May, and his test result came back positive for COVID-19 infection ton the same day. His serology test result is pending.