Seroprevalence of severe acute respiratory syndrome coronavirus 2 antibodies during the third wave of coronavirus disease in the Seoul metropolitan area of Korea.

Objectives: After the third wave of coronavirus disease (COVID-19), by mid-February 2021, approximately 0.16% of the population was confirmed positive, which appeared to be one of the lowest rates worldwide at that time. However, asymptomatic transmission poses a challenge for COVID-19 surveillance. Therefore, a community-based serosurvey of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was conducted to understand the effectiveness of Korea's strong containment strategy. Methods: We collected 5,002 residual sera samples from January 30 to March 3, 2021 from 265 medical facilities in Seoul, 346 in Kyunggi-do' and 57 in Incheon. Among them, 60 samples from tertiary institutions were excluded. We defined the sub-regions according to the addresses of the medical facilities where the specimens were collected. Elecsys Anti-SARS-CoV-2 was used for the screening test, and positivity was confirmed using the SARS-CoV-2 sVNT Kit. Prevalence was estimated using sampling weight and the Wilson score interval for a binomial proportion with a 95% confidence interval. Results: Among the 4,942 specimens, 32 and 25 tested positive for COVID-19 in the screening and confirmatory tests, respectively. The overall crude prevalence of SARS-CoV-2 antibody was 0.51%. The population-adjusted overall prevalence was 0.55% in women and 0.38% in men. The region-specific estimation was 0.67% and 0.30% in Gyeonggi-do and Seoul, respectively. No positive cases were detected in Incheon. Conclusion: The proportion of undetected cases in South Korea remains low. Therefore, an infection control strategy with exhaustive tracing and widespread pre-emptive testing appears to be effective in containing the spread of the virus in the community.

How Does COVID19 Affect Blood Transfusion and Blood Management?

The scientific interest in transfusion medicine as related to COVID19 can be summarized in three important points. 1) How can we identify asymptomatic COVID19 infected potential blood donors from healthy donors, and if the asymptomatic COVID19 infected person has donated blood and it has been transfused, how will it affect the transfused patient? 2) What affect will COVID19 have on blood establishments and medical institutions that use blood? 3) How will convalescent plasma from recovered COVID-19 patients be collected and then be used for patients in need of it? Since COVID19 has a negative effect on blood transfusion and blood management, well developed lines of communication and cooperation from blood establishments, medical institutions, government agencies, and people are urgently needed to overcome the impact of this negative effect.