Delta variant emerges as new threat to Korea

Fear grows that novel mutation may become dominant strain here

With the Delta variant of COVID-19 having been detected in around 80 countries worldwide, fear is rising that the highly infectious mutation of the coronavirus may become the dominant strain in Korea.

The Delta variant, which originated in India, is known to be three times more transmissible than the original virus and 50 percent more contagious than the Alpha variant first reported in the United Kingdom.

It has already become the dominant strain in some countries such as the U.K., where it accounted for more than 99 percent of new COVID-19 infections last week. During the same period, 90 percent of cases in Moscow were due to the variant.

In Korea, of the 2,225 infections due to variants, 1,886 cases were found to be the Alpha strain after genetic sequencing, followed by 190 of the Delta, according to the Korea Disease Control and Prevention Agency (KDCA).

After nine Delta cases from overseas were first identified here in mid-April, the number of infections from the fast-spreading variant surged to 190 in two months.

Adding to the concern is that the current vaccines are less effective against this variant. According to the KDCA, two doses of the Pfizer vaccine showed 87.9 percent effectiveness against the Delta strain, while the AstraZeneca vaccine was 59.8 percent effective — both are lower than the efficacy against the original Alpha at 91.3 percent and 81.5 percent, respectively.

Given the circumstances, it is highly possible that the Delta variant may become the dominant strain in Korea unless stronger measures are imposed to curb the spread, medical experts have warned.

“It is just a matter of time before it becomes the dominant strain,” said Jung Jae-hoon, a professor at Gachon University Gil Medical Center.

“Mutation is a means of survival for the virus, and the Delta strain is the fastest spreading mutated COVID-19 coronavirus yet. Quarantine measures should now be focused on slowing down the spread of this variant,” he said.

Kim Woo-joo, an infectious disease specialist at Korea University Guro Hospital, expressed concern that the forthcoming eased social distancing rules may create a more favorable environment for the spread of the Delta strain.

Starting next month, social distancing rules such as gathering bans and limits to operation hours on entertainment facilities will be significantly eased. Also, mask-wearing outdoors will no longer be required for vaccinated people.

“Lifting the mask wearing rule even for people who have only received one shot of the vaccine, as well as easing distancing measures will make it easier for the Delta variant to become the dominant strain,” Kim said.

The KDCA said it will closely monitor the overseas situation with the Delta variant.

“Although the overall rate of the Delta strain among the total infections due to variants is currently low in Korea, we will continue to monitor the situation and impose stronger quarantine measures if necessary,” KDCA Commissioner Jeong Eun-kyeong said at a briefing Thursday.

Meanwhile, the KDCA reported 610 new infections Wednesday, including 576 local transmissions, raising the total caseload to 153,155.