Infections of the novel coronavirus via unknown channels have begun to increase.
The fourth such patient was confirmed in Seoul on Wednesday, three days after the first case emerged.
On the same day, 18 new cases were confirmed in Daegu and North Gyeongsang Province. Fifteen of them are believed to have contracted COVID-19 from the third patient with an unknown transmission route who was reported a day earlier in Daegu.
The fifth patient is said to have been infected through unknown channels in Yeongcheon, North Gyeongsang Province.
According to the government, the country is entering a “new phase” in its fight against the virus. Doctors say there is growing evidence of transmission in the wider community.
Before infections with unknown transmission routes emerged, those infected with COVID-19 here had either traveled abroad -- mainly to China -- or come into contact with other infected patients.
But the latest five cases (the 29th, 30th, 31st, 32nd and 37th patients) did not fall into either of the two categories. They could have contracted the virus from people who do not know they are infected and are not being monitored by authorities.
Epidemiological investigations have not been completed. However, the five cases -- albeit still a small number -- suggest that community transmission is occurring.
As shown in Daegu, it is worrying that patients with unknown transmission routes had been exposed to their community for a long time before their infections were confirmed.
Geographically, Korea cannot afford to feel at ease. In Japan, more than 70 confirmed cases, including those infected through unclear channels, have been reported. Korea is sandwiched between China, the epicenter of the virus, and Japan, where community spread is suspected. Human and material exchanges are brisk among the three countries.
Community-based transmission is difficult to stop. The authorities must recognize the possibility of community spread and concentrate on the early detection of infections, efforts for symptom relief and the prevention of further infections.
The government is reviewing measures to test all hospitalized pneumonia patients for COVID-19. It is also looking into expanding the testing of suspected cases who are not being monitored and quarantining suspected cases proactively.
It plans to increase the capacity of COVID-19 diagnostic checks from the current level of about 5,000 people a day to 10,000 by the end of this month.
If the number of test subjects increases, small and midsized hospitals may have difficulties conducting more virus tests.
The government needs to work out supplementary measures, such as setting up an organization tasked with making rounds at local medical institutions to secure specimens.
Furthermore, those with suspicious symptoms must report to the public health authorities or visit hospitals with masks on, even if they have never been to China or been in contact with other infected patients. The point is to find hidden cases quickly and stop the virus from spreading.
Attention should also be paid to medically vulnerable people, including the aged, the chronically ill and pregnant women. There have been no deaths from COVID-19 in Korea so far, but like other contagious diseases, those with medical conditions face higher risks. Therefore, the authorities ought to protect nursing hospitals from the virus.
With heightened risk of community transmission, one of the most pressing issues is the return of about 70,000 Chinese students to universities in Korea. They are expected to begin entering Korea as early as this week, as universities postponed the beginning of classes by about two weeks to mid-March.
The Chinese students will be required to quarantine themselves for 14 days after entering Korea, but it is almost impossible for universities to monitor them all. Universities alone should not be held responsible for managing the Chinese students. The government must work with universities to find effective solutions.
Now is the time to carry out a two-track strategy -- strengthening quarantine for arrivals and contacts and preparing thoroughly for community spread.