Korea’s health authorities have confirmed 13 additional cases of BA.2.12.1, an Omicron subvariant, raising the total BA.2.12.1 cases to 19.

According to the Central Disaster and Safety Countermeasures Headquarters (CDSCH) Tuesday, 11 of the 13 BA.2.12.1 cases came from overseas, and two were local infections. It was the first time health officials have confirmed a BA.2.12.1 case originating from Korea.

The BA.2.12.1 is a variant with more than 20 percent higher transmission power than BA.2, also known as stealth Omicron. The subvariant has recently increased in the U.S, which has seen a rise in the number of confirmed cases for seven weeks in a row. In addition, the number of deaths, which had decreased for five weeks in a row, also rose back in the past week.

Korean officials have also confirmed three new BA.4 and BA.5 cases, another Omicron subvariant originating from South Africa. They estimate that BA.4 and BA.5 show a faster detection rate than the BA.2 subvariant.

In South Africa, the BA.4 and BA.5 cases surged from 18 percent of the total infection cases in March to 64 percent in April.

However, Korean health officials stressed that there is no evidence that BA.4 and BA.5 increase the severity of the virus.

"We believe that BA.4 and BA.5 have mutations in the viral surface spike region, so there is a possibility that the variant can evade the immune system," said Park Young-joon, head of the epidemiological investigation team at Korea Disease Control and Prevention Agency (KDCA). "We have identified no particular anomalies in the transmission power of the virus in Korea."

As subvariant cases increase, health experts expressed concerns about the government's recent decision to accept rapid antigen test (RAT) for overseas entrants.

The government decided to recognize negative rapid antigen test results for travelers boarding flights to Korea, on top of polymerase chain reaction (PCR) test results currently allowed, from May 23.

From June, Korea will also increase the time required for international arrivals to undergo a PCR test from one day to three days upon their entry into South Korea.

A health expert feared that the change in quarantine regulations might cause loopholes in Korea's quarantine system, including monitoring the inflow of the Covid-19 variants.

"Since Korea has lifted all domestic quarantine measures except for the wearing of indoor masks, it seems that the government has lowered the requirements for travelers to match a similar level," Professor Kim Woo-joo was quoted as saying by Nocut News, a local news outlet. "There is always a trade-off in policymaking, but if we look at the side effects, there is a risk that the variants will come into Korea more easily and quickly."

Kim stressed that the most important quarantine policy discussed by global health organizations, such as the World Health Organization (WHO), is the strengthening variant monitoring system.

"This means that countries have to detect variants early and prevent the spread of such variants," Kim said. "BA.2.12.1, which is already spreading in the U.S., and the BA.4 and BA.5 subvariants originating from South Africa, is already flowing into Korea."

Kim also expressed concerns that the decreasing trend of Omicron infection cases has slowed down and may not decrease any further.

"There are concerns about a rebound in the number of confirmed cases around the end of May or early June," Kim said. "Even if eased distancing rules relieve people's inconvenience, it should not put more burdens on the quarantine authorities."

Rather than solving the inconvenience of the people, it is more important to prevent the re-emergence of Covid-19 and its variants from appearing in advance, Kim added.

Kim's comments resonate with foreign health experts who have warned that Covid-19 may continue to reinfect people in the future.

"The virus will keep evolving, and there will probably be many people getting many, many reinfections throughout their lives," said Juliet Pulliam, an epidemiologist at Stellenbosch University in South Africa, to the New York Times.

On Tuesday, the KDCA confirmed 35,117 new virus cases, raising the cumulative caseload to 17,830,429.

The death toll came to 23,771, up 27 from the previous day, with a fatality rate of 0.13 percent. However, critically ill patients came to 333, down 12 from a day earlier.

About 44.56 million people, or 86.8 percent of the 52-million population, have been fully vaccinated, according to the agency. In addition, about 33.23 million people had received their first booster shots, representing 64.8 percent, and 3.52 million people had their second booster shots.

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