Asymptomatic Cases and False Negatives Surge... "Hidden Confirmed Cases Feared to be 2 to 10 Times Higher"

PCR Testing Only for High-Risk Groups
90,000 Confirmed Cases Number Distorted
Result Notification Delayed Amid Infection Surge
Concerns Over Testing Capacity Limits

[Asia Economy Reporter Ki Ha-young] #. Won (35), an office worker living in Gwangjin-gu, Seoul, recently experienced a sore throat and tested himself with a self-test kit, but the result was negative. Although there were media reports of positive results on the 4th or 5th attempt, he considered testing a few more times but decided to just take throat medicine. Won said, "I don't trust the test results, but self-test kits are hard to find, so I gave up," adding, "The government is requesting individuals to voluntarily comply with quarantine rules, but in this situation, even if someone is confirmed with COVID-19, they might not know and just pass it by."

Hidden Confirmed Cases "Possibility Up to 10 Times"

The number of new COVID-19 confirmed cases is approaching 100,000 for two consecutive days, breaking record highs daily. Experts estimate that the number of uncounted hidden confirmed cases could be at least twice and up to ten times higher. The rapid spread of the Omicron variant and the failure to detect hidden infections have led to a vicious cycle of explosive increases in confirmed cases.

Professor Kim Woo-joo of the Department of Infectious Diseases at Korea University Guro Hospital said, "Currently, PCR testing is limited to high-risk groups such as those aged 60 and over, so the figure of 90,000 is distorted," adding, "Including hidden infections, the number of confirmed cases is likely at least twice the official count." Professor Chun Eun-mi of the Department of Respiratory Medicine at Ewha Mokdong Hospital also expressed concern, saying, "The current official confirmed cases represent only 1 out of 10, and the other 9 are unknown," and "If diagnosis is delayed, treatment will be delayed, inevitably leading to more critically ill patients and a continuing vicious cycle."

Concerns about false negatives persist. No one knows how many false negatives occur when a person is actually positive but tests negative on a rapid antigen test using a self-test kit. Because false negatives do not undergo additional PCR testing, asymptomatic or mild infections can become new sources of infection. False positives, where a rapid antigen test is positive but PCR test is negative, occur at about 24%.

On this day, the COVID-19 test positivity rate was 15.5%, meaning 1 out of 6 PCR test takers was infected with COVID-19. The positivity rates over the past week were 11.1% → 9.6% → 10.3% → 16.8% → 20.3% → 13.2%.

[Image source=Yonhap News]

Testing Capacity Limits as Positivity Rate Rises

As confirmed cases surge, the time taken to receive PCR test results is also delayed. Normally, results were notified within a day, but some cases now take more than two days. Despite limiting PCR testing to high-risk groups such as those aged 60 and over and close contacts in preparation for the Omicron variant, testing capacity cannot keep up. When PCR testing capacity decreases, the number of PCR tests that can be conducted drops, delaying diagnosis and increasing the number of hidden confirmed cases that cannot be detected.

According to the Central Disease Control Headquarters, the total number of tests conducted over the past week were 483,257 → 570,902 → 546,608 → 324,696 → 280,440 → 650,812 → 600,770, averaging 493,800 tests per day.

The daily testing capacity announced by health authorities is 800,000 to 850,000 tests. Although there appears to be some leeway, testing capacity is expected to face limits soon. As the positivity rate?the proportion of confirmed cases among those tested?increases, it becomes difficult to maintain existing testing methods. Until now, health authorities have used a pooled testing method called "pooling" for 80% of PCR tests. This method mixes samples from multiple test subjects and if the pooled test is negative, all are considered negative. If positive, individual tests are then conducted. This has been applied to groups undergoing preventive screening except for close contacts.

However, with the Omicron variant causing higher positivity rates, the proportion of individual tests instead of pooling is increasing. When samples are collected in groups of five but then tested individually, the daily testing capacity decreases. A health official said, "If the positivity rate continues to rise, PCR testing capacity could decrease by 30%," adding, "Although testing capacity has been continuously expanded, facilities, personnel, and equipment at testing institutions must be prepared, so rapid large-scale expansion is difficult in the short term."

This content was produced with the assistance of AI translation services.