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Background: Influenza and pneumonia are leading causes of morbidity and mortality among the elderly. Although vaccination is a main strategy to prevent these infectious diseases, concerns remain with respect to vaccine effectiveness., Methods: During three influenza seasons (2014-2015, 2015-2016 and 2016-2017), we evaluated the effectiveness of the influenza and pneumococcal vaccines against pneumonia and acute exacerbation of cardiopulmonary diseases among the elderly aged ≥65 years with influenza-like illness (ILI). Demographic and clinical data were collected prospectively., Results: Among 2,119 enrolled cases, 1,302 (61.4%) and 871 (41.1%) received the influenza vaccine and 23-valent pneumococcal polysaccharide vaccine (PPV23), respectively. During an A/H3N2-dominant season with poor influenza vaccine effectiveness (2014-2015 season), neither the influenza vaccine nor PPV23 showed significant effectiveness against pneumonia or acute exacerbation of cardiopulmonary diseases. During seasons with good influenza vaccine effectiveness (2015-2016 and 2016-2017 seasons), the influenza vaccine was effective in preventing pneumonia, but PPV23 was not. In particular, the influenza vaccine was effective in preventing acute exacerbation of heart diseases (75.0%) during the A/H1N1-dominant 2015-2016 season., Conclusion: The influenza vaccine was effective in preventing pneumonia only during vaccine-matched seasons with good effectiveness against circulating influenza viruses. In addition, the influenza vaccine was cardio-protective during a vaccine-matched A/H1N1-dominant season., Competing Interests: The authors have declared that no competing interests exist.

Korea exhibits the highest rates of multidrug resistance among Streptococcus pneumoniae. The increasing use of levofloxacin has raised concern about the dissemination of levofloxacin resistance in dominant multidrug-resistant (MDR) clones of our pneumococcal population. A total of 50 levofloxacin-nonsusceptible S. pneumoniae (MIC, ≥4 μg/mL) collected from a multihospital network from 1996 to 2006 were analyzed for serotype, antibiotic resistance profile, quinolone resistance-determining region mutation, and multilocus sequence type. Most levofloxacin-nonsusceptible S. pneumoniae (94.0%) exhibited an MDR phenotype. This phenotype was closely associated with a limited number of epidemic MDR clones that are well-known key agents of the global spread of antimicrobial resistance in S. pneumoniae. However, the clonal dissemination of levofloxacin-nonsusceptible S. pneumoniae was rare. Levofloxacin-nonsusceptible clones with nonvaccine serotypes increased during the post-vaccine era in this study. This result suggests that Korean clinicians must be aware of the levofloxacin resistance trend and need to be more prudent for the first choice of fluoroquinolone for empiric treatment of respiratory tract infections in clinical setting. Moreover, the emergence of new clones and their variations may be more frequently associated with resistance under this selective pressure, such as the introduction of a 7-valent pneumococcal conjugate vaccine into our community., (Copyright © 2013 Elsevier Inc. All rights reserved.)

We investigated changes of serotypes in Streptococcus pneumoniae and the characteristics of serotypes 6A and 6B in Korean hospitals after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). PCV7 serotypes decreased significantly from 66.8% in 1996-2001 to 41.3% in 2008-2009 (P<0.001). However, serotype 6B did not decrease during these 2 periods (5.7% to 6.4%). Non-PCV7 serotypes that increased significantly were 3 (3.6% to 9.1%), 6A (3.1% to 8.5%), 13/28 (0 to 3.7%), 15 (2.2% to 6.7%), 16.36.37 (0 to 1.2%), 19A (1.2% to 9.7%), and 23A (0 to 1.5%). Multilocus sequence typing indicated that 9 STs were identified among 36 isolates of serotype 6A and 19 among 35 isolates of serotype 6B. No STs were found both in the 2 serotypes. The increase in serotype 6A was associated mainly with ST81, a Spain-23F clone genotype. The association of serotype 6A and ST81 is unique to Korea. Clones of serotype 6B isolates changed between the 2 periods. ST282, the main clone of serotype 6B in the PCV7 period, was found only in Korea. Our study demonstrates changing characteristics of pneumococcal serotypes 6A and 6B isolates in Korea and suggests selective evolution of certain clones in the era of PCV7 vaccination., (Copyright © 2011 Elsevier Inc. All rights reserved.)