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Background: Age-dependent immune responses to coronavirus disease 2019 (COVID-19) vaccinations and breakthrough infections (BIs) in young and middle-aged individuals are unclear. Methods: This nationwide multicenter prospective cohort study analyzed immune responses in participants of the ChAdOx1 (ChAd)-ChAd-mRNA vaccine group using cytometry by time-of-flight, anti-spike protein antibody (Sab) and anti-nucleocapsid antibody (Nab) titers, plaque reduction neutralization tests (PRNTs), and interferon-gamma (IFN-γ) release assays at various time points. Results: We evaluated 347 participants with an average age of 38.9 ± 9.4 years (range: 21–63). There was a significant inverse correlation between age and Sab levels after the second dose (slope − 14.96, P = 0.032), and this was more pronounced after the third dose (slope − 208.9, P < 0.001). After BIs, older participants showed significantly higher Sab titers (slope 398.8, P = 0.001), reversing the age-related decline observed post-vaccination. This reversal was also observed in PRNTs against wild-type SARS-CoV-2 and the BA.1 and BA.5 variants. IFN-γ responses increased markedly after the third dose and Bis, but showed a weak positive correlation with age, without statistical significance. Immune cell profiling revealed an age-dependent decrease in the proportions of B-cell lineage cells. The proportions of naive CD4+ and CD8+ T cells were inversely correlated with age, whereas the proportions of mature T cell subsets with memory function, including memory CD4+ T, CD8+ TEM, CD8+ TEMRA, and TFH cells, increased with age. Conclusions: Age-dependent waning of the serologic response to COVID-19 vaccines occurred even in middle-aged individuals, but was reversed after BIs. IFN-γ responses were preserved, compensating for the decrease in naive T cell populations, with an increase in memory T cell populations. [ABSTRACT FROM AUTHOR]

The Korean Society of Infectious Diseases has been regularly developing guidelines for adult immunization since 2007. In 2023, the guidelines for the following seven vaccines were revised: influenza, herpes zoster, pneumococcal, tetanus-diphtheria-pertussis (Tdap), human papillomavirus (HPV), meningococcal, and rabies vaccines. For the influenza vaccine, a recommendation for enhanced vaccines for the elderly was added. For the herpes zoster vaccine, a recommendation for the recombinant zoster vaccine was added. For the pneumococcal vaccine, the current status of the 15-valent pneumococcal conjugate vaccine and 20-valent PCV was described. For the Tdap vaccine, the possibility of using Tdap instead of tetanus-diphtheria vaccine was described. For the HPV vaccine, the expansion of the eligible age for vaccination was described. For the meningococcal vaccine, a recommendation for the meningococcal B vaccine was added. For the rabies vaccine, the number of pre-exposure prophylaxis doses was changed. This manuscript documents the summary and rationale of the revisions for the seven vaccines. For the vaccines not mentioned in this manuscript, the recommendations in the 3rd edition of the Vaccinations for Adults textbook shall remain in effect., Competing Interests: HJC, JYS, JYC, HJC are editorial board, WBP is associate editor, DGL is editor-in-chief of Infect Chemother; however, they did not involve in the peer reviewer selection, evaluation, and decision process of this article. Otherwise, no potential conflicts of interest relevant to this article was reported., (© 2024 by The Korean Society of Infectious Diseases, Korean Society for Antimicrobial Therapy, The Korean Society for AIDS, and Korean Society of Pediatric Infectious Diseases.)

This review addresses the escalating challenge posed by antibiotic resistance, highlighting its profound impact on global public health, including increased mortality rates and healthcare expenditures. The review focuses on the need to adopt the One Health approach to effectively manage antibiotic usage across human, animal, and environmental domains. Antimicrobial stewardship programs (ASPs) are considered as comprehensive strategies that encompass both core and supplementary initiatives aimed at enhancing prudent antibiotic use. The 2021 "Guidelines on Implementing ASP in Korea" introduced such strategies, with a strong emphasis on fostering multidisciplinary and collaborative efforts. Furthermore, the "Core Elements for Implementing ASPs in Korean General Hospitals," established in 2022, provide a structured framework for ASPs, delineating leadership responsibilities, the composition of interdisciplinary ASP teams, a range of interventions, and continuous monitoring and reporting mechanisms. In addition, this review examines patient-centric campaigns such as "Speak Up, Get Smart" and emphasizes the pivotal role of a multidisciplinary approach and international cooperation in addressing the multifaceted challenges associated with antibiotic resistance.