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The flight information display system at Incheon International Airport shows flights arriving from London on Sunday after the South Korean government lifted a ban on direct flights from the UK. (Yonhap News)

The rate for estimating the spread of major COVID-19 variants (UK, South African, Brazilian) within South Korea has risen to nearly 25%, nearly double that of last week's 12.8%.

The UK variant has been spreading rapidly and accounts for much of this change. Also, the South African variant, known to be vaccine-resistant, spread from a nursing home to an elementary school in Gyeonggi Province. Seven secondary cases of transmission of the Indian variant have been confirmed, which is worrisome as the World Health Organization (WHO) has recently reclassified this variant as being of major concern for its high transmissibility.

South Korean health authorities have recently joined local governments in a new task force to block the spread, but critics worry they may be behind in their response.

The Central Disease Control Headquarters (CDCH) announced Tuesday the results of local transmission tests conducted on May 2 and Saturday. According to an analysis of 567 confirmed cases, 141 people – 129 South Korean nationals and 12 foreigners – were infected with a major variant.

The UK variant accounted for 123 cases, and the South African for 18. This means the local detection rate of major variant cases has risen to 24.9%.

The rate shows a sharp incline, going from 5% in mid-April to 11% in late April to the numbers now. And if the number of cases of overseas transmission is included in the totals (35 of 74 people who contracted the disease abroad), then last week's variant detection rate rose to 27.5%.

Each week, the CDCH takes samples from 15% of all confirmed cases and runs genetic tests to estimate the total number of variant cases.

The CDCH announced the same day, "The UK variant has been spreading throughout Ulsan since it first appeared in a cluster outbreak [including cases at a funeral home and a golf driving range] there in early February. The South African variant broke out in a nursing home in Bucheon, [Gyeonggi Province.] From there, it spread to a school and elsewhere."

The South African variant comprises 159 cases to date, and 93 – 60% – of these cases were identified in Gyeonggi Province.

Lee Sang-won, director of the epidemiological analysis team at the CDCH, said, "We believe that transmissions of the UK variant in Ulsan and the South African variant in Bucheon are in decline after reaching their peak."

"Sporadic outbreaks can occur for the time being, and we must be on guard to block them," he added.

This means that the government is expanding the scope of contact tracing in areas where variants have spread, evaluating the situation daily, and conducting preemptive inspections of facilities and groups that may be exposed to viruses. However, it is still unclear how the South African variant first broke out at the Bucheon nursing home.

The Indian variant has also spread to the local community from overseas arrivals, causing alarm, as the WHO has warned of its high transmissibility.

A total of 58 cases of the variant have been detected in Korea as of this morning. There were only two such cases until March, but 54 were added in April.

Park Young-joon, head of the epidemiological research team at the CDCH, said, "Out of 58 cases, 51 were contracted abroad. Most of the remaining seven were family contacts of overseas travelers, and these are judged to be cases of local transmission."

The government, on May 4, tightened some relevant restrictions, requiring that all new arrivals from India be required to quarantine for seven days at government facilities and home for another seven. However, secondary transmission is already underway, likely from arrivals who were quarantining at home before the implementation of this rule.

It has also been confirmed that the CDCH lagged in announcing that the California virus variant was detected in 47.9% of North Gyeongsang Province cases last month.

Lee Min-ja, head of the infectious diseases control department in North Gyeongsang Province, said, "The central government does not provide information on variants for local governments unless they are classified as 'major' variants, so it was only through the latest news report that we obtained precise data and learned that the California variant was so prevalent here."

CDCH meeting discussions are strictly focused on major variants, she added, noting that whereas cases of major variants are specially quarantined in single rooms, cases of other variants are quarantined as usual.

With a speed of transmission up to 20% higher than usual, the California variant has been classified as a major variant in the US. If the transmission speed and seriousness of this variant are later confirmed, the WHO may change its classification in line with that of the Indian variant.

Acknowledging criticism that the CDCH was late to notify local governments, Park said, "There are several stages of information sharing, so there seems to have been a delay."

By Choi Ha-yan, staff reporter

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