Osong Public Health and Research Perspectives

Original Articles

mRNA vaccine effectiveness against SARS-CoV-2 B.1.617.2 (Delta) and B.1.1.529 (Omicron) variant transmission from home care cases to household contacts in South Korea: Hanul Park, Young Joon Park, Sang Eun Lee, Min Jei Lee, Hyungtae Ahn; Osong Public Health Res Perspect. 2022;13(6):435-442. Published online November 28, 2022; DOI: https://doi.org/10.24171/j.phrp.2022.0243

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Objectives
Household contacts of confirmed cases of coronavirus disease 2019 (COVID-19) areexposed to a high risk of viral transmission, and secondary incidence is an important indicatorof community transmission. This study analyzed the secondary attack rate and mRNA vaccineeffectiveness against transmission (VET) for index cases (patients treated at home) confirmedto be infected with the Delta and Omicron variants.Methods: The subjects of the study were 4,450 index cases and 10,382 household contacts.Logistic regression analysis was performed to compare the secondary attack rate byvaccination status, and adjusted relative risk and 95% confidence intervals were identified.Results: The secondary attack rate of the Delta variant was 27.3%, while the secondary attackrate of the Omicron variant was 29.8%. For the Delta variant, groups with less than 90 daysand more than 90 days after 2 doses of mRNA vaccination both showed a VET of 37%. For theOmicron variant, a 64% VET was found among those with less than 90 days after 2 doses ofmRNA vaccination.Conclusion: This study provides useful data on the secondary attack rate and VET of mRNAvaccines for household contacts of COVID-19 cases in South Korea.

Citations

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Household secondary attack rates and risk factors during periods of SARS-CoV-2 Delta and Omicron variant predominance in the Republic of Korea
Jin Lee, Mijeong Ko, Seontae Kim, Dosang Lim, Gemma Park, Sang-Eun Lee
Osong Public Health and Research Perspectives.2023; 14(4): 263. CrossRef

Investigation of SARS-CoV-2 lineages and mutations circulating in a university-affiliated hospital in South Korea analyzed using Oxford Nanopore MinION sequencing: Hyaekang Kim, Sung Hee Chung, Hyun Soo Kim, Han-Sung Kim, Wonkeun Song, Ki Ho Hong, Jae-Seok Kim; Osong Public Health Res Perspect. 2022;13(5):360-369. Published online October 11, 2022; DOI: https://doi.org/10.24171/j.phrp.2022.0183

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Abstract PDF Supplementary Material: Objectives
Despite the introduction of vaccines, treatments, and massive diagnostic testing, the evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to overcome barriers that had slowed its previous spread. As the virus evolves towards increasing fitness, it is critical to continue monitoring the occurrence of new mutations that could evade human efforts to control them. Methods: We performed whole-genome sequencing using Oxford Nanopore MinION sequencing on 58 SARS-CoV-2 isolates collected during the ongoing coronavirus disease 2019 pandemic at a tertiary hospital in South Korea and tracked the emergence of mutations responsible for massive spikes in South Korea. Results: The differences among lineages were more pronounced in the spike gene, especially in the receptor-binding domain (RBD), than in other genes. Those RBD mutations could compromise neutralization by antibodies elicited by vaccination or previous infections. We also reported multiple incidences of Omicron variants carrying mutations that could impair the diagnostic sensitivity of reverse transcription-polymerase chain reaction-based testing. Conclusion: These results provide an understanding of the temporal changes of variants and mutations that have been circulating in South Korea and their potential impacts on antigenicity, therapeutics, and diagnostic escape of the virus. We also showed that the utilization of the nanopore sequencing platform and the ARTIC workf low can provide convenient and accurate SARS-CoV-2 genomic surveillance even at a single hospital.

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