Taipei, June 19 (CNA) The highly infectious Delta variant of COVID-19, which has been spreading rapidly across the globe, has been confirmed in only five cases in Taiwan, all of which were imported, the Central Epidemic Command Center (CECC) said Saturday.

First detected in India, the Delta variant is likely to become the world's dominant strain of COVID-19, because of its "significantly enhanced transmissibility," according to the World Health Organization (WHO).

In Taiwan, however, genetic sequencing carried out by the CECC in a sample of 278 COVID-19 cases since last October has found only five infections caused by the Delta variant, all of which were imported, CECC official Lo Yi-chun (羅一鈞) said at a press briefing.

The most prevalent strain was the Alpha variant, which was first detected in the United Kingdom, and accounted for 199 out of the 278 cases the CECC examined, according to Lo.

Another six of the cases were of the Beta variant, which was initially reported in South Africa, while four of the cases were of the Gamma variant that was first identified in Brazil, Lo said.

He said the Delta variant now accounts for 90 percent of the new cases in the U.K., mainly among people who are unvaccinated or have received only their first shot.

With the Delta variant, the risk of household transmission is 64 percent higher than with the Alpha variant, and it is also believed to raise the risk of hospitalization, Lo said.

He said, however, there is no need to extend Taiwan's mandatory 14-day quarantine period for incoming travelers, as some experts have suggested, because there is no evidence that the Delta variant has a longer incubation period than the others.

The CECC, therefore, will maintain its policy of vaccination and tight border controls as the best defense against the various COVID-19 strains currently in circulation, Lo said.