title: Efficacy of 23-valent pneumococcal polysaccharide vaccine in preventing community-acquired pneumonia among immunocompetent adults: A systematic review and meta-analysis of randomized trials.
abstract: BACKGROUND
  Data on the efficacy of the 23-valent pneumococcal polysaccharide vaccine (PPV-23) in preventing adult community-acquired pneumonia (CAP) among the target population of individuals aged over 65 years and high-risk individuals aged 19-64 years are conflicting. As the Advisory Committee on Immunization Practices (ACIP) has recently demonstrated PPV-23 is likely beneficial to immunocompromised adults by the Grading, Assessment, Development, and Evaluation (GRADE) framework, we conducted meta-analysis to examine its efficacy in an immunocompetent population.
  
  
  METHODS
  We searched the PUBMED, EMBASE, and Cochrane Library databases for randomized trials. Overall relative risks (RRs) with 95% confidential intervals (CIs) were calculated, and the Cochrane Q test (p, I(2)) was performed. Outcomes were assessed by the GRADE framework.
  
  
  RESULTS
  Seven randomized trials involving 156,010 participants were included in this meta-analysis. High-quality evidence revealed that PPV-23 was weakly associated with the prevention of all-cause pneumonia ([RR] 0.87, [95%CI] 0.76-0.98, p=0.11, I(2)=43%), especially among the target population ([RR] 0.72, [95%CI] 0.69-0.94, p=0.58 I(2)=0%), the elderly group aged over 40 years ([RR] 0.80, [95%CI] 0.69-0.94) and the Japanese population ([RR] 0.72, [95%CI] 0.59-0.88, p=0.24, I(2)=30%). The target population included adults aged over 65 years and patients at high risk of pneumonia due to chronic lung disease, chronic obstructive pulmonary disease or living in a nursing home. Protective trends of PPV-23 in the outcomes of pneumococcal pneumonia ([RR] 0.54, [95%CI] 0.18-1.65, p=0.01, I(2)=77%) and mortality due to pneumonia ([RR] 0.67, [95%CI] 0.43-1.04, p=0.67, I(2)=0%) were observed, although the results were statistically insignificant, possibly due to the small number of trials included. PPV-23 did not prevent all-cause mortality ([RR] 1.04, [95%CI] 0.87-1.24, p=0.95, I(2)=0%).
  
  
  CONCLUSIONS
  PPV-23 provided weak protection against all-cause pneumonia in an immunocompetent population, especially among the target population. The additional benefit of PPV-23 in preventing CAP further supports its application in the target population.
authors.affiliation: Department of Respiratory Medicine, Peking University Third Hospital, Beijing, China. Electronic address: 424259600@qq.com.
authors.forename: Wen-Qi
authors.initials: WQ
authors.lastname: Diao
authors.affiliation: Department of Respiratory Medicine, Peking University Third Hospital, Beijing, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Shen
authors.affiliation: Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Pan-Xi
authors.initials: PX
authors.lastname: Yu
authors.affiliation: Department of Respiratory Medicine, Peking University Third Hospital, Beijing, China.
authors.forename: Bei-Bei
authors.initials: BB
authors.lastname: Liu
authors.affiliation: Department of Respiratory Medicine, Peking University Third Hospital, Beijing, China. Electronic address: puh3_hb@bjmu.edu.cn.
authors.forename: Bei
authors.initials: B
authors.lastname: He
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017714:Community-Acquired Infections / Q000517:prevention & control*; D006301:Health Services Needs and Demand; D006801:Humans; D008875:Middle Aged; D022242:Pneumococcal Vaccines / Q000627:therapeutic use*; D011018:Pneumonia, Pneumococcal / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D055815:Young Adult
chemical_list: C414006:23-valent pneumococcal capsular polysaccharide vaccine; D022242:Pneumococcal Vaccines
keywords: 23-Valent pneumococcal polysaccharide vaccine; Community-acquired pneumonia; Efficacy; Immunocompetent; Meta-analysis