TAIPEI (Taiwan News) — Taiwan's Epidemic Command Center (CECC) on Thursday (Sept. 16) announced that six out of 10 imported COVID-19 cases that day were classified as breakthrough infections, but emphasized the effectiveness of vaccines in reducing the risk of severe illness and death.

A breakthrough infection is defined as a person who has tested positive for COVID-19 at least 14 days after they have completed the full vaccine schedule. Philip Lo (羅一鈞), deputy head of the CECC’s medical response division, on Thursday announced that six out of the 10 imported cases reported that day were considered breakthrough infections.

The 10 imported cases reported on Thursday included five men and five women between the ages of 20 and 30. Between Aug. 31 and Sept. 14, they entered Taiwan from South Africa (case No. 16,215), the U.S. (case Nos. 16,216, 16,218, 16,219, and 16,223), Japan (case Nos. 16,217 and 16,222), the United Arab Emirates (case No. 16,220), Indonesia (case No. 16,224), and India (case No. 16,225).

Lo stated that five of the breakthrough cases had received two doses of the Pfizer-BioNTech vaccine, while one had been given two doses of the AstraZeneca jab. When asked by a reporter if this was the largest number of breakthrough cases reported in a single day in Taiwan, Lo said he would have to review the center's records to provide a definitive answer.

However, Lo stressed that the Ct values of nine of the cases were all over 30, while the results of one are still pending. Lo said this high Ct value indicates the cases had been infected for a relatively longer period of time.

These cases include Taiwanese citizens who were confirmed with COVID-19 and recovered while in the U.S. and the UAE in July and August. He suggested the continued severity of the global pandemic could have resulted in trace amounts of the virus detected in these individuals.

Because of the continuing reports of breakthrough infections, Lo said vaccinated individuals who arrive in Taiwan from overseas must still undergo quarantine. Lo added that vaccines can significantly reduce the risk of severe illness and death, so everyone should get vaccinated.