Subscribe to RSS
Please copy the URL and add it into your RSS Feed Reader.
https://www.thieme-connect.de/rss/thieme/en/10.1055-s-00000075.xml
Download PDF
Semin Respir Crit Care Med 2025; 46(01): 020-030
DOI: 10.1055/a-2588-6965
DOI: 10.1055/a-2588-6965
Review Article
Next-Generation Pneumococcal Vaccines for Children and Adults
Authors
Funding None.
Abstract
Streptococcus pneumoniae remains one of the leading causes of mortality and morbidity in children and in the elderly worldwide. Pneumococcal conjugated vaccines (PCVs) have reduced invasive and noninvasive pneumococcal disease in children and adults. However, challenges persist due to serotype replacement, epidemiological diversity, and global inequalities in vaccine access. The future of PCVs is structured around three major areas of innovation: expanding antigenic coverage, developing serotype-independent formulations, and introducing advanced technological platforms such as the multiple antigen presenting system. The challenge is to better improve immunogenicity beyond serotypes and to extend the global impact of vaccines with more equitable and effective global rates of vaccination.
Keywords
conjugated vaccines - pneumococcal disease - serotype replacement - Streptococcus pneumoniae - next-generation vaccinesPublication History
Accepted Manuscript online:
16 April 2025
Article published online:
06 June 2025
© 2025. Thieme. All rights reserved.
Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA
-
References
- 1 Torres A, Blasi F, Dartois N, Akova M. Which individuals are at increased risk of pneumococcal disease and why? Impact of COPD, asthma, smoking, diabetes, and/or chronic heart disease on community-acquired pneumonia and invasive pneumococcal disease. Thorax 2015; 70 (10) 984-989
- 2 Rodgers GL, Whitney CG, Klugman KP. Triumph of pneumococcal conjugate vaccines: overcoming a common foe. J Infect Dis 2021; 224 (12, suppl 2): S352-S359
- 3 Pollard AJ, Perrett KP, Beverley PC. Maintaining protection against invasive bacteria with protein-polysaccharide conjugate vaccines. Nat Rev Immunol 2009; 9 (03) 213-220
- 4 Yu X, Wang H, Ma S, Chen W, Sun L, Zou Z. Estimating the global and regional burden of lower respiratory infections attributable to leading pathogens and the protective effectiveness of immunization programs. Int J Infect Dis 2024; 149: 107268
- 5 Balsells E, Guillot L, Nair H, Kyaw MH. Serotype distribution of Streptococcus pneumoniae causing invasive disease in children in the post-PCV era: a systematic review and meta-analysis. PLoS One 2017; 12 (05) e0177113
- 6 Pilishvili T, Lexau C, Farley MM. et al; Active Bacterial Core Surveillance/Emerging Infections Program Network. Sustained reductions in invasive pneumococcal disease in the era of conjugate vaccine. J Infect Dis 2010; 201 (01) 32-41
- 7 Bennett JC, Deloria Knoll M, Kagucia EW. et al. Global impact of ten-valent and 13-valent pneumococcal conjugate vaccines on invasive pneumococcal disease in all ages (the PSERENADE project): a global surveillance analysis. Lancet Infect Dis 2025; 25 (04) 457-470
- 8 Ciruela P, Izquierdo C, Broner S. et al; Catalan Working Group on Invasive Pneumococcal Disease. The changing epidemiology of invasive pneumococcal disease after PCV13 vaccination in a country with intermediate vaccination coverage. Vaccine 2018; 36 (50) 7744-7752
- 9 Yildirim I, Lapidot R, Shaik-Dasthagirisaheb YB. et al. Invasive pneumococcal disease after 2 decades of pneumococcal conjugate vaccine use. Pediatrics 2024; 153 (01) 153
- 10 Levy C, Varon E, Ouldali N, Béchet S, Bonacorsi S, Cohen R. Changes in invasive pneumococcal disease spectrum after 13-valent pneumococcal conjugate vaccine implementation. Clin Infect Dis 2020; 70 (03) 446-454
- 11 Sings HL, De Wals P, Gessner BD. et al. Effectiveness of 13-valent pneumococcal conjugate vaccine against invasive disease caused by serotype 3 in children: a systematic review and meta-analysis of observational studies. Clin Infect Dis 2019; 68 (12) 2135-2143
- 12 Garcia Quesada M, Peterson ME, Bennett JC. et al. Serotype distribution of remaining invasive pneumococcal disease after extensive use of ten-valent and 13-valent pneumococcal conjugate vaccines (the PSERENADE project): a global surveillance analysis. Lancet Infect Dis 2025; 25 (04) 445-456
- 13 van der Linden M, Imöhl M, Perniciaro S. Limited indirect effects of an infant pneumococcal vaccination program in an aging population. PLoS One 2019; 14 (08) e0220453
- 14 Nakashima K, Fukushima W. Strategies for pneumococcal vaccination in older adults in the coming era. Hum Vaccin Immunother 2024; 20 (01) 2328963
- 15 Menéndez R, Torres A, España PP. et al; CAPA Study Group. Pneumococcal serotypes associated with community-acquired pneumonia hospitalizations in adults in Spain, 2016-2020: the CAPA study. Microorganisms 2023; 11 (11) 11
- 16 Self WH, Johnson KD, Resser JJ. et al; PNEUMO Study Investigators. Prevalence, clinical severity, and serotype distribution of pneumococcal pneumonia among adults hospitalized with community-acquired pneumonia in Tennessee and Georgia, 2018-2022. Clin Infect Dis 2024; 79 (04) 838-847
- 17 Griffith A, Golden AR, Lefebvre B. et al. Invasive pneumococcal disease surveillance in Canada, 2021-2022. Can Commun Dis Rep 2024; 50 (05) 121-134
- 18 Dagan R, Patterson S, Juergens C. et al. Comparative immunogenicity and efficacy of 13-valent and 7-valent pneumococcal conjugate vaccines in reducing nasopharyngeal colonization: a randomized double-blind trial. Clin Infect Dis 2013; 57 (07) 952-962
- 19 Moberley S, Holden J, Tatham DP, Andrews RM. Vaccines for preventing pneumococcal infection in adults. Cochrane Database Syst Rev 2013; 2013 (01) CD000422
- 20 Farrar JL, Childs L, Ouattara M. et al. Systematic review and meta-analysis of the efficacy and effectiveness of pneumococcal vaccines in adults. Pathogens 2023; 12 (05) 12
- 21 Andrews NJ, Waight PA, George RC, Slack MPE, Miller E. Impact and effectiveness of 23-valent pneumococcal polysaccharide vaccine against invasive pneumococcal disease in the elderly in England and Wales. Vaccine 2012; 30 (48) 6802-6808
- 22 Yamana H, Ono S, Michihata N, Uemura K, Jo T, Yasunaga H. Effect of the 23-valent pneumococcal polysaccharide vaccine on the incidence of hospitalization with pneumonia in adults aged ≥65 years: retrospective cohort study using a population-based database in Japan. Clin Microbiol Infect 2023; 29 (07) 904-910
- 23 Hanquet G, Krizova P, Dalby T. et al; SpIDnet group1. Serotype replacement after introduction of 10-valent and 13-valent pneumococcal conjugate vaccines in 10 countries, Europe. Emerg Infect Dis 2022; 28 (01) 137-138
- 24 Durando P, Faust SN, Fletcher M, Krizova P, Torres A, Welte T. Experience with pneumococcal polysaccharide conjugate vaccine (conjugated to CRM197 carrier protein) in children and adults. Clin Microbiol Infect 2013; 19 (Suppl. 01) 1-9
- 25 Elemraid MA, Rushton SP, Shirley MDF. et al; North East of England Paediatric Respiratory Infection Study Group. Impact of the 7-valent pneumococcal conjugate vaccine on the incidence of childhood pneumonia. Epidemiol Infect 2013; 141 (08) 1697-1704
- 26 Koshy E, Murray J, Bottle A, Sharland M, Saxena S. Impact of the seven-valent pneumococcal conjugate vaccination (PCV7) programme on childhood hospital admissions for bacterial pneumonia and empyema in England: national time-trends study, 1997-2008. Thorax 2010; 65 (09) 770-774
- 27 Tocheva AS, Jefferies JMC, Rubery H. et al. Declining serotype coverage of new pneumococcal conjugate vaccines relating to the carriage of Streptococcus pneumoniae in young children. Vaccine 2011; 29 (26) 4400-4404
- 28 Miller E, Andrews NJ, Waight PA, Slack MPE, George RC. Herd immunity and serotype replacement 4 years after seven-valent pneumococcal conjugate vaccination in England and Wales: an observational cohort study. Lancet Infect Dis 2011; 11 (10) 760-768
- 29 Weinberger DM, Malley R, Lipsitch M. Serotype replacement in disease after pneumococcal vaccination. Lancet 2011; 378 (9807): 1962-1973
- 30 Mrkvan T, Pelton SI, Ruiz-Guiñazú J, Palmu AA, Borys D. Effectiveness and impact of the 10-valent pneumococcal conjugate vaccine, PHiD-CV: review of clinical trials and post-marketing experience. Expert Rev Vaccines 2018; 17 (09) 797-818
- 31 Esposito S, Principi N. Impacts of the 13-valent pneumococcal conjugate vaccine in children. J Immunol Res 2015; 2015: 591580
- 32 Grant LR, Begier E, Theilacker C. et al. Multicountry review of Streptococcus pneumoniae serotype distribution among adults with community-acquired pneumonia. J Infect Dis 2024; 229 (01) 282-293
- 33 Torres A, Menéndez R, España PP. et al; CAPA Study Group. The evolution and distribution of pneumococcal serotypes in adults hospitalized with community-acquired pneumonia in spain using a serotype-specific urinary antigen detection test: the CAPA study, 2011-2018. Clin Infect Dis 2021; 73 (06) 1075-1085
- 34 Bonten MJM, Huijts SM, Bolkenbaas M. et al. Polysaccharide conjugate vaccine against pneumococcal pneumonia in adults. N Engl J Med 2015; 372 (12) 1114-1125
- 35 van Deursen AMM, van Houten MA, Webber C. et al. Immunogenicity of the 13-valent pneumococcal conjugate vaccine in older adults with and without comorbidities in the community-acquired pneumonia immunization trial in adults (CAPiTA). Clin Infect Dis 2017; 65 (05) 787-795
- 36 Vadlamudi NK, Parhar K, Altre Malana KL, Kang A, Marra F. Immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine compared to 23-valent pneumococcal polysaccharide in immunocompetent adults: a systematic review and meta-analysis. Vaccine 2019; 37 (08) 1021-1029
- 37 Davies LRL, Cizmeci D, Guo W. et al. Polysaccharide and conjugate vaccines to Streptococcus pneumoniae generate distinct humoral responses. Sci Transl Med 2022; 14 (656) eabm4065
- 38 McLaughlin JM, Jiang Q, Isturiz RE. et al. Effectiveness of 13-Valent pneumococcal conjugate vaccine against hospitalization for community-acquired pneumonia in older US adults: a test-negative design. Clin Infect Dis 2018; 67 (10) 1498-1506
- 39 Hsiao A, Lewis N, Hansen J. et al. Effectiveness of 13-valent pneumococcal conjugate vaccine against vaccine-type invasive pneumococcal disease in older adults. Vaccine 2025; 44: 126543
- 40 Martinon-Torres F, Wysocki J, Szenborn L. et al; V114-025 PNEU-PED-EU-1 study group. A phase III, multicenter, randomized, double-blind, active comparator-controlled study to evaluate the safety, tolerability, and immunogenicity of V114 compared with PCV13 in healthy infants (PNEU-PED-EU-1). Vaccine 2023; 41 (21) 3387-3398
- 41 Benfield T, Rämet M, Valentini P. et al. Safety, tolerability, and immunogenicity of V114 pneumococcal vaccine compared with PCV13 in a 2+1 regimen in healthy infants: A phase III study (PNEU-PED-EU-2). Vaccine 2023; 41 (15) 2456-2465
- 42 Chapman TJ, Olarte L, Dbaibo G. et al. PCV15, a pneumococcal conjugate vaccine, for the prevention of invasive pneumococcal disease in infants and children. Expert Rev Vaccines 2024; 23 (01) 137-147
- 43 Lupinacci R, Rupp R, Wittawatmongkol O. et al; V114-029 PNEU-PED study group. A phase 3, multicenter, randomized, double-blind, active-comparator-controlled study to evaluate the safety, tolerability, and immunogenicity of a 4-dose regimen of V114, a 15-valent pneumococcal conjugate vaccine, in healthy infants (PNEU-PED). Vaccine 2023; 41 (05) 1142-1152
- 44 Platt HL, Greenberg D, Tapiero B. et al; V114-008 Study Group. A phase II trial of safety, tolerability and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, compared with 13-valent pneumococcal conjugate vaccine in healthy infants. Pediatr Infect Dis J 2020; 39 (08) 763-770
- 45 Banniettis N, Horn M, Sadarangani M. et al; V114-031 (PNEU-LINK) study group. Safety and tolerability of V114 pneumococcal vaccine in infants: a phase 3 study. Pediatrics 2023; 152 (01) 152
- 46 Stacey HL, Rosen J, Peterson JT. et al. Safety and immunogenicity of 15-valent pneumococcal conjugate vaccine (PCV-15) compared to PCV-13 in healthy older adults. Hum Vaccin Immunother 2019; 15 (03) 530-539
- 47 Platt HL, Cardona JF, Haranaka M. et al. A phase 3 trial of safety, tolerability, and immunogenicity of V114, 15-valent pneumococcal conjugate vaccine, compared with 13-valent pneumococcal conjugate vaccine in adults 50 years of age and older (PNEU-AGE). Vaccine 2022; 40 (01) 162-172
- 48 Song JY, Chang CJ, Andrews C. et al; V114-016 (PNEU-PATH) study group. Safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, followed by sequential PPSV23 vaccination in healthy adults aged ≥50 years: a randomized phase III trial (PNEU-PATH). Vaccine 2021; 39 (43) 6422-6436
- 49 Peterson JT, Stacey HL, MacNair JE. et al. Safety and immunogenicity of 15-valent pneumococcal conjugate vaccine compared to 13-valent pneumococcal conjugate vaccine in adults ≥65 years of age previously vaccinated with 23-valent pneumococcal polysaccharide vaccine. Hum Vaccin Immunother 2019; 15 (03) 540-548
- 50 Senders S, Klein NP, Tamimi N. et al. A phase three study of the safety and immunogenicity of a four-dose series of 20-valent pneumococcal conjugate vaccine in healthy infants. Pediatr Infect Dis J 2024; 43 (06) 596-603
- 51 Korbal P, Wysocki J, Jackowska T. et al. Phase 3 safety and immunogenicity study of a three-dose series of twenty-valent pneumococcal conjugate vaccine in healthy infants and toddlers. Pediatr Infect Dis J 2024; 43 (06) 587-595
- 52 Essink B, Sabharwal C, Cannon K. et al. Pivotal phase 3 randomized clinical trial of the safety, tolerability, and immunogenicity of 20-valent pneumococcal conjugate vaccine in adults aged ≥18 years. Clin Infect Dis 2022; 75 (03) 390-398
- 53 Hurley D, Griffin C, Young M. et al. Safety, tolerability, and immunogenicity of a 20-valent pneumococcal conjugate vaccine (PCV20) in adults 60 to 64 years of age. Clin Infect Dis 2021; 73 (07) e1489-e1497
- 54 Cannon K, Elder C, Young M. et al. A trial to evaluate the safety and immunogenicity of a 20-valent pneumococcal conjugate vaccine in populations of adults ≥65 years of age with different prior pneumococcal vaccination. Vaccine 2021; 39 (51) 7494-7502
- 55 Cho J-Y, Lee H, Wannaadisai W, Vietri J, Chaiyakunapruk N. Systematic literature review of cost-effectiveness analyses of adult 15- and 20-valent pneumococcal vaccines. Vaccine 2025; 46: 126656
- 56 Rosenthal M, Stoecker C, Leidner AJ, Cho B-H, Pilishvili T, Kobayashi M. Cost-effectiveness of 15-valent or 20-valent pneumococcal conjugate vaccine for U.S. adults aged 65 years and older and adults 19 years and older with underlying conditions. Vaccine 2025; 44: 126567
- 57 Mendes D, Averin A, Atwood M. et al. Cost-effectiveness of using a 20-valent pneumococcal conjugate vaccine to directly protect adults in England at elevated risk of pneumococcal disease. Expert Rev Pharmacoecon Outcomes Res 2022; 22 (08) 1285-1295
- 58 Danelian G, Burton L, Bayley T. et al. The impact and cost-effectiveness of pneumococcal immunisation strategies for the elderly in England. Vaccine 2024; 42 (18) 3838-3850
- 59 de Boer PT, van Werkhoven CH, van Hoek AJ. et al. Higher-valency pneumococcal conjugate vaccines in older adults, taking into account indirect effects from childhood vaccination: a cost-effectiveness study for the Netherlands. BMC Med 2024; 22 (01) 69
- 60 Cannon K, Cardona JF, Yacisin K. et al. Safety and immunogenicity of a 20-valent pneumococcal conjugate vaccine coadministered with quadrivalent influenza vaccine: a phase 3 randomized trial. Vaccine 2023; 41 (13) 2137-2146
- 61 Fitz-Patrick D, Young M, Yacisin K. et al. Randomized trial to evaluate the safety, tolerability, and immunogenicity of a booster (third dose) of BNT162b2 COVID-19 vaccine coadministered with 20-valent pneumococcal conjugate vaccine in adults ≥65 years old. Vaccine 2023; 41 (28) 4190-4198
- 62 Kobayashi M, Leidner AJ, Gierke R. et al. Use of 21-valent pneumococcal conjugate vaccine among u.s. adults: recommendations of the advisory committee on immunization practices - United States, 2024. MMWR Morb Mortal Wkly Rep 2024; 73 (36) 793-798
- 63 Platt HL, Bruno C, Buntinx E. et al; STRIDE-3 Study Group. Safety, tolerability, and immunogenicity of an adult pneumococcal conjugate vaccine, V116 (STRIDE-3): a randomised, double-blind, active comparator controlled, international phase 3 trial. Lancet Infect Dis 2024; 24 (10) 1141-1150
- 64 Scott P, Haranaka M, Choi JH. et al; STRIDE-6 Study Group. A phase 3 clinical study to evaluate the safety, tolerability, and immunogenicity of V116 in pneumococcal vaccine-experienced adults 50 years of age or older (STRIDE-6). Clin Infect Dis 2024; 79 (06) 1366-1374
- 65 King LM, Lewnard JA. Health-economic burden attributable to novel serotypes in candidate 24- and 31-valent pneumococcal conjugate vaccines. Vaccine 2024; 42 (26) 126310
- 66 Wassil J, Sisti M, Fairman J. et al. A phase 2, randomized, blinded, dose-finding, controlled clinical trial to evaluate the safety, tolerability, and immunogenicity of a 24-valent pneumococcal conjugate vaccine (VAX-24) in healthy adults 65 years and older. Vaccine 2024; 42 (25) 126124
- 67 Wassil J, Sisti M, Fairman J. et al. Evaluating the safety, tolerability, and immunogenicity of a 24-valent pneumococcal conjugate vaccine (VAX-24) in healthy adults aged 18 to 64 years: a phase 1/2, double-masked, dose-finding, active-controlled, randomised clinical trial. Lancet Infect Dis 2024; 24 (03) 308-318
- 68 Masomian M, Ahmad Z, Gew LT, Poh CL. Development of next generation Streptococcus pneumoniae vaccines conferring broad protection. Vaccines (Basel) 2020; 8 (01) 132
- 69 Musher DM, Anderson R, Feldman C. The remarkable history of pneumococcal vaccination: an ongoing challenge. Pneumonia 2022; 14 (01) 5
- 70 Oliveira GS, Oliveira MLS, Miyaji EN, Rodrigues TC. Pneumococcal vaccines: past findings, present work, and future strategies. Vaccines (Basel) 2021; 9 (11) 9
- 71 Afshar D, Rafiee F, Kheirandish M, Ohadian Moghadam S, Azarsa M. Autolysin (lytA) recombinant protein: a potential target for developing vaccines against pneumococcal infections. Clin Exp Vaccine Res 2020; 9 (02) 76-80
- 72 Wang Y, Shi G, Wang X. et al. Preliminary evaluation of the safety and immunogenicity of a novel protein-based pneumococcal vaccine in healthy adults aged 18-49: a phase ia randomized, double blind, placebo-controlled clinical study. Vaccines (Basel) 2024; 12 (08) 12
- 73 Vorobyev DS, Petukhova ES, Volokh YV, Semenova IB. Analysis of immunobiological properties of recombinant Streptococcus pneumoniae pneumolysin. Bull Exp Biol Med 2024; 177 (02) 248-251
- 74 Chichili GR, Smulders R, Santos V. et al. Phase 1/2 study of a novel 24-valent pneumococcal vaccine in healthy adults aged 18 to 64 years and in older adults aged 65 to 85 years. Vaccine 2022; 40 (31) 4190-4198
- 75 Mohammadzadeh M, Pourakbari B, Mahmoudi S, Keshtkar A, Habibi-Anbouhi M, Mamishi S. Efficacy of whole-cell pneumococcal vaccine in mice: a systematic review and meta-analysis. Microb Pathog 2018; 122: 122-129
- 76 Morais V, Texeira E, Suarez N. Next-generation whole-cell pneumococcal vaccine. Vaccines (Basel) 2019; 7 (04) 7
- 77 Zhang F, Lu YJ, Malley R. Multiple antigen-presenting system (MAPS) to induce comprehensive B- and T-cell immunity. Proc Natl Acad Sci U S A 2013; 110 (33) 13564-13569
- 78 Guo M, Guo X, Zhang C. et al. Novel pneumococcal protein-polysaccharide conjugate vaccine based on biotin-streptavidin. Infect Immun 2022; 90 (01) e0035221
- 79 Malley R, Lu Y-J, Sebastian S, Zhang F, Willer DO. Multiple antigen presenting system (MAPS): state of the art and potential applications. Expert Rev Vaccines 2024; 23 (01) 196-204
- 80 Borys D, Rupp R, Smulders R. et al. Safety, tolerability and immunogenicity of a novel 24-valent pneumococcal vaccine in toddlers: a phase 1 randomized controlled trial. Vaccine 2024; 42 (10) 2560-2571
- 81 Borys D, Smulders R, Haranaka M. et al. Safety, reactogenicity, and immunogenicity of a novel 24-valent pneumococcal vaccine candidate in healthy, pneumococcal vaccine-naïve Japanese adults: a phase 1 randomized dose-escalation trial. Vaccine 2025; 44: 126545
- 82 Updates ACIP. ACIP updates: recommendations for use of 20-valent pneumococcal conjugate vaccine in children - United States, 2023. MMWR Morb Mortal Wkly Rep 2023; 72 (39) 1072
- 83 Kobayashi M, Pilishvili T, Farrar JL. et al. Pneumococcal vaccine for adults aged ≥19 years: recommendations of the advisory committee on immunization practices, United States, 2023. MMWR Recomm Rep 2023; 72 (03) 1-39
- 84 Niyibitegeka F, Russell FM, Jit M, Carvalho N. Inequitable distribution of global economic benefits from pneumococcal conjugate vaccination. Vaccines (Basel) 2024; 12 (07) 12
- 85 Wahl B, O'Brien KL, Greenbaum A. et al. Burden of Streptococcus pneumoniae and Haemophilus influenzae type b disease in children in the era of conjugate vaccines: global, regional, and national estimates for 2000-15. Lancet Glob Health 2018; 6 (07) e744-e757
- 86 Ben-Shimol S, Givon-Lavi N, Greenberg D. et al; Israel Bacteremia and Meningitis Active Surveillance Group. Impact of pneumococcal conjugate vaccines introduction on antibiotic resistance of Streptococcus pneumoniae meningitis in children aged 5 years or younger, Israel, 2004 to 2016. Euro Surveill 2018; 23 (47) 23
- 87 Richter SS, Diekema DJ, Heilmann KP, Dohrn CL, Riahi F, Doern GV. Changes in pneumococcal serotypes and antimicrobial resistance after introduction of the 13-valent conjugate vaccine in the United States. Antimicrob Agents Chemother 2014; 58 (11) 6484-6489
- 88 Fenoll A, Granizo JJ, Aguilar L. et al. Temporal trends of invasive Streptococcus pneumoniae serotypes and antimicrobial resistance patterns in Spain from 1979 to 2007. J Clin Microbiol 2009; 47 (04) 1012-1020
- 89 Kobayashi M, Leidner AJ, Gierke R. et al. Expanded recommendations for use of pneumococcal conjugate vaccines among adults aged ≥50 years: recommendations of the advisory committee on immunization practices - United States, 2024. MMWR Morb Mortal Wkly Rep 2025; 74 (01) 1-8