Taiwan reports 1st local Omicron cases

台灣傳出第一例Omicron本土病例

Taipei hotel cluster infection caused by Omicron


TAIPEI (Taiwan News) — Two COVID infections that had been considered imported have been reclassified as local and determined to be caused by the Omicron variant, marking Taiwan's first reported local cases of the highly transmissible strain.

During a press conference on Monday (Jan. 3), Central Epidemic Command Center (CECC) head Chen Shih-chung (陳時中) said a cluster infection in a Taipei epidemic prevention hotel was found to have been caused by the Omicron variant. Two imported cases at the hotel that were announced on Dec. 28 and Dec. 30, Nos. 17,058 and 17,099, have been re-diagnosed as local cases after an epidemiological investigation.

1. Omicron overseas case numbers

CECC officials believe the two were infected by case No. 17,085 while in the same epidemic prevention hotel. Their rationale is that case No. 17,058 arrived from Shenzhen, China, where no Omicron cases had been reported at the time of the person's departure.

Case No. 17,099 entered from Japan, where only 32 Omicron cases had been reported by Dec. 15, and were all detected at the airport. However, case No. 17,085 arrived from the U.S. at a time when there were already thousands of cases in the country.

2. Mutation pattern

A second reason they believe case No. 17,085 to be the source is the pattern in mutations as the virus travels from one patient to another. CECC advisor Chang Shan-chwen (張上淳) said that the S protein gene sequence of all three cases was exactly the same.

After carrying out whole genome sequencing, there were two sites where mutation had occurred between case Nos. 17, 085; 17,058; and 17,099. In addition, there were four points of mutation between case Nos. 17,085 and 17,099.

Chang said that small changes in the genetic makeup of the virus occur after transmission. Based on the evolution of the mutations, officials believe case 17,085 first transmitted the virus to 17,058 before later passing it on to 17,099.

3. Ct values

In addition, case No. 17,085's Ct value rose from 16 to 27, indicating that the infection is nearing its end. However, No. 17,058's Ct value dropped from 26 to 20, while 17,099's Ct value fell from 21 to 17, indicating that both are at an earlier stage of infection.

When asked how the transmission might have occurred, Chang said it is possible there had been "environmental pollution" of viral particles. Although a total of 14 samples taken from inside the hotel came back negative, Chang said it is still possible the guests had been exposed to the virus indoors.

Chang said another concern is that the virus had been transported via the air-conditioning system. He pointed out that there were several rooms in which air-conditioning and ventilation experts had recommended improvements.

Background

Case No. 17,085 arrived from the U.S. on Dec. 22, while case No. 17,099 returned from Japan on Dec. 16. Both had opted to spend all 14 days of their quarantine in the hotel and both stayed on the fifth floor.

Case No. 17,085 began experiencing symptoms and tested positive for COVID while undergoing quarantine. Case No. 17,099 also tested positive while still in quarantine.

After returning from China on Dec. 14, Case No. 17,058, who had opted for the "10+4" quarantine option for the Lunar New Year holiday, stayed on the sixth floor of the hotel. The individual tested positive during the last four days of their quarantine period while staying in their basement at home.

Omicron case count

Philip Lo (羅一鈞), deputy head of the CECC’s medical response division, announced that Taiwan has now confirmed 89 imported cases of Omicron in addition to the two local infections.