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A disease control staffer directs arriving international travelers at Incheon International Airport’s Terminal 1 on the morning of Feb. 4, amid reports of South Korea’s first domestic cluster infection involving a virus variant originating in the UK. (Yonhap News)

The possibility of a fourth COVID-19 wave erupting in South Korea in March and April cannot be ruled out when risk factors such as the spread of variants are factored in, the South Korean government says.

Amid the news that a variant was spread domestically due to violations of disease control guidelines during a patient’s quarantine period, experts are calling for more stringent quarantining and other measures.

A total of 451 new COVID-19 cases were confirmed by the end of the day on Feb. 3. The government’s first reference to the possibility of a fourth wave comes as the new caseload remains stubbornly high and more cases of variants being spread domestically have been discovered.

“There are concerns that we could see another wave in March or April,” said Yoon Tae-ho, head of the disease control team for the Central Disaster Management Headquarters (CDMH), in a briefing that day.

“We need to prepare for that possibility, which neither the experts nor the disease control authorities are completely ruling out,” he said.

In addition to risk factors such as the spread of virus variants and a rise in the reproduction number (R0, pronounced “R-naught”), the predictions also reflect fears that disease control guidelines may not be fully observed when March and April arrive as the public grows increasingly exhausted with social distancing.

The reproduction number, which represents the average number of other people infected by a single patient, had averaged 0.92 for the week as of Feb. 4, up from 0.82 the week before.

As concerns about virus variants grow, disease control authorities belatedly announced that they were exploring additional measures.

The day before, authorities said a virus variant originating in the UK had been detected in four patients from a cluster infection in South Gyeongsang and South Jeolla provinces, where 38 people to date have tested positive after a chain of transmission from the index patient (first confirmed case) to family members, more distant relatives and the relatives’ acquaintances. Violations of quarantine guidelines were found to have taken place, including visits by relatives to the index patient’s home.

“Outside visitors must obtain permission from disease control authorities [from the presiding local government or public health center] before visiting [a patient’s home],” stressed Kwon Jun-wook, deputy director of the Korea Disease Control and Prevention Agency (KDCA).

On Feb. 4, Prime Minister Chung Sye-kyun called for a “renewed search for potential holes in the self-quarantine process for arriving international travelers” and the “development of supplementary measures.”

In connection with this, Yoon explained, “There have been discussions about the need to actively assume a high probability of variant strains in epidemiologically related cases and to manage them accordingly.”

“We need to expand preemptive testing at patients’ workplaces and schools and increase our virus analysis efforts for travelers arriving from the Middle East,” he said.

Kim Woo-joo, a professor of infectious disease at Korea University Guro Hospital, said, “The vaccines that have currently been developed are known to be less effective against the variants.”

“If we want to prevent the variants from gaining a foothold before full-scale vaccination begins, we ought to consider facility-based quarantine [for arriving travelers] to absolutely ensure no transmission among family members,” he said.

But the current 11 temporary community centers are not capable of accommodating all travelers arriving from overseas.

Commenting on the facility-based quarantine idea, Kwon said, “Some things are less than perfect due to overall resource limitations.” With around 4,000 international passengers arriving each day on average, a 14-day quarantine would require facilities capable of accommodating 56,000 people.

“We will consider all possibilities and announce stronger measures in the near future,” Kwon said.

The same day, disease control authorities announced findings from a sweep of COVID-19 antibodies in samples taken from 5,284 participants in a national health and nutrition survey between Apr. 21 and Dec. 12 last year.

Five participants were found to possess antibodies, three of whom had previously tested positive for COVID-19. The other two participants had not been reported to disease control authorities, suggesting that silent spreading may have taken place within local communities.

By Seo Hye-mi, staff reporter

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