Health officials on alert against post-holiday resurge of Covid-19 cases

The health authorities predicted on Thursday that Covid-19 cases might resurge down the road as the impact of a massive population movement during the Chuseok holiday might appear from next week.

The Korea Disease Control and Prevention Agency (KDCA) confirmed 1,716 new virus cases, including 1,698 local infections, raising the total caseload to 292,699. The country saw eight more deaths from the virus, increasing total cases to 2,427 with a fatality rate of 0.83 percent.

"Although the number of confirmed cases is smaller than expected, the government believes that the number of confirmed cases will increase in the next few days," Ministry of Health and Welfare Spokesperson Son Young-rae said during a daily press briefing. "There are concerns about whether the epidemic will increase in the Seoul metro region and spread to the rest of the country due to the recent Chuseok holiday."

Son stressed that the government would have to keep watching the situation this and next week before judging the pattern of epidemics in the greater Seoul and non-capital areas and the impact of Chuseok (Sept. 19-22). "Afterward, we can discuss the adjustment of the social distancing level," Son said.

He added that people who have not completed the Covid-19 vaccination should receive the test promptly if symptoms occur.

Earlier this month, the government extended the social distancing rules of Level 4, the highest of its four-tier system, for Seoul and the surrounding Gyeonggi Province, and Level 3 for other regions until Oct. 3, limiting the number of private gatherings and restaurant business hours.

But the bans were eased during the Chuseok holiday that ended Wednesday, allowing family gatherings of up to eight people on the condition that four of them are fully vaccinated.

Health officials also expressed concerns about the increase in the share of new virus cases with unknown infection routes.

"The increase in the share of new virus cases with unknown infection routes means that it has become more difficult to find the source of the infection that the confirmed person came into contact with," said Park Hyang, who oversees antivirus measures at the Central Disaster Management Headquarters. "The reason for the declining share of manageable cases within the quarantine network is either because the number of absolute confirmed cases has increased or epidemiological investigation slowed down."

Also, the Delta variant, which has many asymptomatic infections, is spreading locally, Park added.

"It is time to introduce an information and communication technology (ICT) tracing method that can self-check the route of infection, rather than the current method of finding confirmed cases and following contacts," Park said.

The quarantine authorities said that the number of breakthrough infection cases has increased in Korea, with people who received Janssen's vaccine accounting for most cases.

The Central Disaster and Safety Countermeasures Headquarters have confirmed 5,880 cases of breakthrough infection as of Sep. 12. The figure accounts for 0.040 percent of the 14,611,702 people who completed vaccination, or 40.2 cases per 100,000 vaccinated people.

By vaccine type, the breakthrough rate of the Janssen vaccine was the highest with 0.161 percent (161.2 cases per 100,000 people), followed by Pfizer (0.034 percent), AstraZeneca (0.028 percent), and Moderna (0.024 percent).

The government pointed out that Janssen accounted for the most breakthrough infections as the age group that mainly received the vaccine consists of those in their 30s and 40s, who lead most active social lives, which makes the possibility of exposure to the virus after completing the vaccination is higher than that of other vaccine recipients.

Commenting on the suspicion that the Janssen vaccine, which ends with a single dose, might be less effective than a vaccine that requires two doses, Hong Jung-ik, a member of the government's Covid-19 Vaccination Response Promotion Team, said that the limitations of a single dose vaccine still requires more monitoring.

"Depending on the results, the government will review providing booster shots," he said.

Korea has vaccinated 36,570,105 people – 11,086,426 with the AstraZeneca vaccine, 19,767,475 with Pfizer's vaccine, 1,415,538 with Janssen's vaccine, and 4,300,666 with Moderna's vaccine – with the first shot of the vaccine up 27,400 from the previous day. The figure accounts for 71.2 percent of the total population.