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Purpose: Previous studies have demonstrated the immunogenicity and safety of the co-administration of the trivalent inactivated influenza vaccine (IIV3) with the polysaccharide pneumococcal vaccine (PPV) or pneumococcal conjugate vaccine (PCV). However, there is no direct comparison study that evaluates the immunogenicity and safety of IIV3 given concomitantly with PCV13 or PPV23 in the elderly. Materials and Methods: During the 2012-2013 influenza vaccination period, 224 healthy elderly volunteers aged 65 years and older randomly received IIV3 given concomitantly with either PCV13 (PCV13+IIV3) or PPV23 (PPV23+IIV3) in a 1:1 ratio. Serum hemagglutination-inhibiting antibodies for IIV3 were measured at the time of vaccination and 1 month after vaccination. Adverse events were recorded prospectively in a clinical diary during a 7-day period. Results: A total of 220 participants blood samples for analysis of immunogenicity and kept a clinical diary for safety analysis (PCV13+IIV3, n=110; PPV23+IIV3, n=110). One month after vaccination, both groups satisfied the Committee for Medical Products for Human Use criteria for A/H1N1, A/H3N2 and B strains, showing comparable seroprotection rates, seroconversion rates and geometric mean titer fold. The assessments of immunogenicity were similar in both groups. The most common local and systemic reactions were pain at the injection site and generalized myalgia. They were generally mild or moderate in intensity. The adverse events were not statistically different between the two groups. Conclusion: PCV13+IIV3 and PPV23+IIV3 demonstrated similar immunogenicity and safety in the elderly. [ABSTRACT FROM AUTHOR]

• The effectiveness of repeated influenza vaccination was investigated. • Repeated vaccination was not effective during consecutive flu A/H3N2 epidemics. • About 80% of Korean elderly people receive influenza vaccination annually. • Poor influenza vaccine effectiveness was pronounced among the elderly population. Annually, about 80% of the Korean elderly aged ≥65 years receive influenza vaccination. Repeated annual vaccination has been suggested as an important factor of poor influenza vaccine effectiveness (VE), though reported conflicting results. During the consecutive A/H3N2-dominant influenza seasons between 2012 and 2015, we comparatively evaluated the VE (repeated vs. current season only) against laboratory-confirmed influenza, pneumonia and hospitalization in the elderly aged ≥65 years with influenza-like illness (ILI). Clinical and demographic data were collected prospectively, and vaccination status of prior and current seasons was verified using the immunization registry data of Korean Centers for Disease Control and Prevention. During the first A/H3N2-dominant season in 2012–2013, influenza vaccine showed statistically significant effectiveness against influenza A infection only and when vaccinated in the current season only (VE 53%, 95% CI 15–77). In the latter two seasons (2013–2015 years), the adjusted VE for influenza A was indistinguishable between repeated vaccination and vaccination in the current season only. During consecutive influenza A/H3N2 epidemics, poor influenza vaccine effectiveness may be more pronounced among the elderly population with a high annual vaccine uptake rate. [ABSTRACT FROM AUTHOR]

In the 2016–2017 season, the A(H3N2) influenza epidemic presented an unusual early peak pattern compared with past seasons in South Korea. The interim vaccine effectiveness (VE) of influenza vaccination in preventing laboratory-confirmed influenza was estimated using test-negative design through the tertiary hospital-based influenza surveillance system in South Korea. From 1 September, 2016 to 7 January, 2017, adjusted VE of influenza vaccination in preventing laboratory-confirmed A(H3N2) was -52.1% (95% confidence interval [CI], -147.2 to 6.4); -70.0% (95% CI, -212.0 to 7.4) in 19–64 years and 4.3% (95% CI, -137.8 to 61.5) in the elderly. Circulating A(H3N2) viruses belonged to the three phylogenetic subclades of 3C.2a, differently to A/Hong Kong/4801/2014, the current vaccine strain. Amino acid substitutions in hemagglutinin of circulating viruses seem to contribute to low VE. In conclusion, interim VE analysis presented that the protection of laboratory-confirmed influenza by seasonal influenza vaccination did not show the statistical significance in South Korea in the 2016–2017 influenza season. [ABSTRACT FROM AUTHOR]

Purpose: Women who are pregnant, planning to become pregnant in the influenza season or caring for infant 6-59 months of age are identified as priority groups for influenza vaccination. Vaccination rate is presumed to be low in those women. The purpose of this study was to investigate perceptions of childbearing age women about influenza vaccination. Materials and Methods: Childbearing age women visiting the department of Obstetrics and Gynecology in 3 University hospitals in Seoul and Gyeonggi-do province were surveyed. Individual interviews were performed to them with questionnaire for 2 months from April to May 2012. Demographic data, Immunization history, general understanding and factors associated with vaccination were asked. Results: Three hundred fifty-five (71.0%) of total 500 reproductive age women had the experience of influenza vaccination. Among 343 women who has been pregnant at least once, 48 women (16.4%) had vaccination during pregnancy, and 46 of them got vaccination since 2009. One hundred ninety women of total 500 women responded that they would get vaccination if pregnant in the next influenza season (38.0%). In multivariate analysis, statistically significant factors associated with plans of influenza vaccination in pregnancy were as follows: experience of childbirth (odds ratio [OR], 1.97; 95% CI, 1.32 to 2.93), high level of education (OR, 1.96; 95% CI, 1.22 to 3.15), previous influenza vaccination (OR, 1.88; 95% CI, 1.17 to 3.01). Conclusion: Influenza vaccine coverage on childbearing age women including pregnant women is low because of misperception of vaccination during pregnancy. It is necessary for healthcare provider to correct misunderstanding and to recommend vaccination actively. [ABSTRACT FROM AUTHOR]

Abstract: The 2009 influenza pandemic was caused by a novel triple-reassortant influenza A/H1N1 virus that was further recombined with a Eurasian pig flu virus. Vaccination is a key countermeasure for disease; however, little data assessing vaccine effectiveness (VE) against the pandemic H1N1 virus are available. We conducted a matched case–control study to assess effectiveness of the 2009 influenza A/H1N1 monovalent vaccine against laboratory-confirmed, medically attended influenza patients. Subjects included in the study were ≥10 years of age and were treated at five university hospitals in the Republic of Korea (ROK) from December 2009 through March 2010. For subjects visiting outpatient clinics with influenza-like illness (ILI), real time reverse transcription polymerase chain reaction (rRT-PCR) was used to diagnose 2009 H1N1 influenza virus infection. Subjects with positive rRT-PCR were classified as cases, while those testing negative were controls. A valid vaccination corresponded to ≥14 days between receiving a dose of vaccine and symptom onset. Overall, 416 ILI subjects were analyzed, and 60 (14.4%) were vaccinated with the 2009 influenza A/H1N1 monovalent vaccine. The overall VE against pandemic 2009 A/H1N1 virus illness after adjustment for age group and presence of chronic medical conditions was 73.4% (95% confidence interval [CI]=49.1–86.1%). Both vaccine formulations (unadjuvanted and MF-59 adjuvanted) showed a statistically significant VE. In conclusion, the 2009 influenza A/H1N1 monovalent vaccine was substantially protective against pandemic influenza in the ROK during the 2009–2010 season. [Copyright &y& Elsevier]

Abstract: In a pandemic, the development of an effective influenza vaccine is the most important subject from the view of public health. This study was performed to evaluate the immunogenicity and safety of inactivated, monovalent H1N1 2009 vaccine (Green Cross Corporation, Yongin, Korea) among healthy adults aged 19–64 years (Group 1) and the elderly aged ≥65 years (Group 2) in a two-dose regimen, 21 days apart. At baseline, 28 of 454 participants (6.1%) had hemagglutination-inhibition titers of ≥1:40 with no significant difference between age groups (p =0.27). There was an apparent dose-dependent antibody response; participants receiving the dose of 30μg hemagglutinin (HA) showed higher geometric mean titers (GMTs) than the 15μg HA group in both age groups. Despite the rates of seroprotection and seroconversion were significantly higher with 30μg HA formulation than 15μg HA formula in Group 2, there was no definite difference in Group 1 irrespective of vaccine formula. Significant GMT elevation after the second dose was not noted in either age group, regardless vaccine formulations. No deaths, vaccine-related serious adverse events, or immediate unsolicited adverse reactions occurred during the study periods. [Copyright &y& Elsevier]

Abstract: The elderly have been considered as the priority group for influenza vaccination, but their influenza vaccine-induced antibody was believed to decline more rapidly. Long-term immunogenicity of the influenza vaccine among the elderly was evaluated as compared to young adults. Serum hemagglutinin inhibition (HI) titers were determined at pre- and post-vaccination periods (at 1, 6, and 12 months after vaccination). Of the 1018 subjects, 716 (70.3%) were followed up during a 12-month period. Seroprotection rates at 1 month post-vaccination ranged from 70.1% to 90.3% depending on the age group and influenza vaccine virus strain. At 6 months post-vaccination, seroprotection rates for all three strains had declined significantly in adults ≥65 years (P <0.01), but still met the EMEA criteria. Low pre-vaccination HI titer (<1:40) and advanced age were associated with early decline of HI titers, falling below seroprotective levels around 6 months after vaccination. [Copyright &y& Elsevier]