Objectives
The main Brucella species causing human infections in the Republic of Korea is Brucella abortus, which uses cattle as its host. However, since 2014, Brucella melitensis, which uses sheep and goats as hosts, has also been identified. This study investigated whether a shift has occurred in the predominant species of Brucella pathogens.
Methods
Brucellosis is a class 3 infectious disease requiring mandatory reporting and registration in the Korea Disease Control and Prevention Agency’s infectious disease surveillance system (http://is.kdca.go.kr). Cases from 2014 to 2023 were studied, and whole-genome sequencing analysis was conducted using BruMLSA21.
Results
Out of 51 patients, males (45 patients, 88.2%) were predominantly affected. Twenty-five patients (49%) came from the livestock industry, and within the livestock sector group, the route of infection occurred exclusively through contact (25/25, 100%), whereas in other occupations, it was split between contact (9/26 patients, 34.6%) and ingestion (8/26 patients, 30.8%). Among the 31 patients who underwent Brucella culture tests, B. melitensis was found to be more prevalent than B. abortus (14 patients, 45.2% vs. 11 patients, 35.5%). In all cases where B. melitensis was isolated, the infections were of foreign origin, consistent with the results of BruMLSA21.
Conclusion
Regular monitoring of the causative agent of brucellosis is necessary due to its varying host preferences and antibiotic resistance. Furthermore, given the increasing prevalence of B. melitensis worldwide, changes in dietary habits (e.g., increased lamb consumption), and the increase in foreign workers and Chinese immigrants, a multi-ministerial One Health response will be required.

Objectives
In 2021, the effectiveness of the COVID-19 vaccine was analyzed among people living in the Honam region (Gwangju, Jeollanam-do, Jeollabuk-do, and Jeju) of the Republic of Korea. And we investigated changes in the dominant virus strain.
Methods
This study used the data provided by the Korean Ministry of the Interior and Safety for individuals ≥12 years old in the Honam region, and the Integrated Disease and Health Management System of the Korea Centers for Disease Control and Prevention for COVID-19-vaccinated individuals as of December 31, 2021. Statistical analyzes were performed using IBM SPSS ver. 23.0. The occurrence of confirmed cases by vaccination status, the relative risk, and vaccine effectiveness by vaccine type were calculated.
Results
In 2021, the COVID-19 vaccination rate in Honam was 88.6%. The overall vaccine effectiveness (after 2 and 3 doses) was 98.7% (p<0.001). and the breakthrough infection rate was 0.16%. From week 21 to week 27 of 2021 (June 27 to July 3), the genome sequencing results were mostly alpha variants. The Delta variant emerged as the dominant variant after 27 weeks and the Omicron variant was found at 50 weeks (December 5–11).
Conclusion
Vaccine effectiveness changed with the outbreak of new variants of the virus as well as over time as antibody levels decreased. that the prevention effectiveness of vaccination in Honam was >98%, and the effect among persons who received 2 doses was >90% regardless of the vaccine type. Although vaccine effectiveness decreased because of reduced antibody levels over time (as observed in breakthrough infections), receiving a booster dose restored the neutralizing antibody levels.