{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T05:02:44Z","timestamp":1784869364144,"version":"3.55.0"},"reference-count":50,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T00:00:00Z","timestamp":1784678400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: 23-valent pneumococcal polysaccharide vaccine (PPV23) effectiveness against community-acquired pneumonia (CAP) remains controversial, with critical gaps in low-coverage settings and beyond 5 years post-vaccination. We estimated real-world PPV23 effectiveness against CAP hospitalization and characterized its duration among elderly adults in a low-coverage region. Methods: A multicenter matched case\u2013control study was conducted across 14 hospitals in Eastern China (2018\u20132022). Cases were patients aged \u226560 years hospitalized with clinically diagnosed CAP. Up to three controls per case were matched on sex, age (\u00b13 years), admission date (\u00b15 days), hospital, and residential community. Conditional logistic regression estimated vaccine effectiveness (VE), adjusting for chronic comorbidities and healthcare utilization. Results: Among 6645 cases and 15,806 controls, 5-year PPV23 coverage was 2.14% (cases) and 2.76% (controls). PPV23 was associated with a 22.5% reduction in CAP hospitalization (adjusted VE = 22.5%, 95% CI: 4.1% to 37.3%). Protection was concentrated in non-severe CAP (adjusted VE = 25.7%, 95% CI: 7.0% to 40.7%), with no significant effect in severe CAP (adjusted VE = \u221211.7%, 95% CI: \u2212115.1% to 42.0%). Extending the exposure window to 6 years yielded no significant VE (adjusted VE = 17.3%, 95% CI: \u22121.8% to 32.8%). Conclusions: PPV23 provides meaningful protection against CAP hospitalization in elderly adults in low-coverage settings, only for non-severe disease. Waning efficacy beyond 5 years supports revaccination at that interval.<\/jats:p>","DOI":"10.3390\/vaccines14070646","type":"journal-article","created":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T01:01:28Z","timestamp":1784768488000},"page":"646","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Protection and Duration of 23-Valent Pneumococcal Polysaccharide Vaccine Against Hospitalization for Community-Acquired Pneumonia in Older Adults with Low Vaccination Coverage: A Multicenter Matched Case\u2013Control Study in China"],"prefix":"10.3390","volume":"14","author":[{"given":"Tianchi","family":"Yang","sequence":"first","affiliation":[{"name":"Department of Human Resources & Medical Education, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xingqiu","family":"Ying","sequence":"additional","affiliation":[{"name":"General Office, Xiaoshan District Center for Disease Control and Prevention (Xiaoshan District Health Supervision Institute), Hangzhou 311203, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoqing","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Public Health, Ningbo University, Ningbo 315211, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junzhe","family":"Shao","sequence":"additional","affiliation":[{"name":"Department of Human Resources & Medical Education, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lixia","family":"Ye","sequence":"additional","affiliation":[{"name":"Department of STD and HIV\/AIDS Control and Prevention, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yumin","family":"Tao","sequence":"additional","affiliation":[{"name":"Ningbo Kangning Hospital, Ningbo 315010, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2429235","DOI":"10.1080\/21645515.2024.2429235","article-title":"Pneumococcal Disease Burden in High-Risk Older Adults: Exploring Impact of Comorbidities, Long-Term Care Facilities, Antibiotic Resistance, and Immunization Policies through a Narrative Literature Review","volume":"20","author":"Cheong","year":"2024","journal-title":"Hum. 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