Actual COVID-19 Infections 6.6%p Higher Than Confirmed Case Counts... Overseas Up to Twice as Much

US CDC Test Results
Antibody Holders Through Infection
2.38 Times the Officially Reported Confirmed Cases

[Image source=Yonhap News]

[Asia Economy Reporter Kim Young-won] According to the COVID-19 antibody positivity rate survey conducted by the quarantine authorities, the antibody positivity rate from natural infection was 6.6 percentage points higher than the cumulative confirmed cases during the same period. In overseas countries, the antibody possession rate was up to twice the number of confirmed cases, showing a larger gap than the domestic survey.

The Korea Disease Control and Prevention Agency (KDCA) announced on the 14th the results of a COVID-19 antibody positivity rate survey conducted on 1,612 participants aged 10 and above from the Korea National Health and Nutrition Examination Survey. According to the survey, the overall antibody positivity rate was 94.9%, and the antibody positivity rate from natural infection as of April was 36.1%. The antibody positivity rate refers to the proportion of individuals possessing antibodies that bind to the S antigen and N antigen of the COVID-19 virus. S antibodies can be produced through both natural infection and vaccination, while N antibodies are formed only through natural infection.

The natural infection antibody positivity rate identified in the survey was 6.6 percentage points higher than the nationwide cumulative COVID-19 incidence rate of 29.5% for those aged 10 and above during the same period. The quarantine authorities interpret this gap as cases of infection that were not diagnosed with COVID-19. Kwon Jun-wook, director of the National Institute of Health, stated, "We believe that undiagnosed infections have also increased due to the Omicron wave."

In overseas countries, the gap between antibody survey results through serology and the number of confirmed cases was larger than in this domestic survey. According to blood test results conducted by the U.S. Centers for Disease Control and Prevention (CDC) from January 27 to February 26, 57.7% of Americans were found to have antibodies from infection. The actual COVID-19 infections identified through antibody testing were 2.38 times the confirmed case rate of 24.2% relative to the population reported by U.S. authorities.

Similarly, in the United Kingdom, the number of people with antibodies from infection was confirmed to be higher than the number of confirmed cases reported by authorities. The UK Health Security Agency (UKHSA) conducted a serological surveillance program on citizens aged 17 and above from January 31 to March 27. The antibody positivity rate from infection was 45.0%, approximately 14.6 percentage points higher than the confirmed case rate of 30.4% relative to the UK population during the same period.

The KDCA explained that the scale of this antibody positivity rate survey is small and that the survey regions vary monthly, limiting the ability to accurately determine the size of the natural infection population. In terms of survey scale, the U.S. surveyed 45,810 people and the UK surveyed 14,507 people for antibody possession, whereas the domestic survey only included 1,612 people, about one-tenth of the UK’s sample size.

Accordingly, the KDCA plans to conduct a large-scale antibody positivity rate survey to accurately determine the size of the natural infection population and analyze epidemic risk factors. The survey will target 10,000 people quarterly nationwide across 17 cities and provinces aged 5 and above, aiming for a total of 30,000 people this year. The survey is scheduled to begin on the 8th of next month. Previously, the government announced plans to start a large-scale survey in May and release the first results in July, but the schedule was delayed due to administrative procedures.

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