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Tinggaard M, Slotved HC, Jørgensen CS, Kronborg G, Benfield T. Predictors of serological non-response to the 13-valent pneumococcal conjugate vaccine followed by the 23-valent polysaccharide vaccine among adults living with HIV. Vaccine 2023; 41:4414-4421. [PMID: 37316406 DOI: 10.1016/j.vaccine.2023.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/16/2023] [Accepted: 06/04/2023] [Indexed: 06/16/2023]
Abstract
BACKGROUND People living with HIV (PLWH) have higher incidence of pneumococcal disease compared to people without HIV. Immunization with pneumococcal vaccines is recommended, but serological non-response to pneumococcal vaccination is common for largely unknown reasons. METHODS PLWH on antiretroviral treatment and no prior pneumococcal vaccination received the 13-valent pneumococcal conjugate vaccine (PCV13) followed 60 days later by the 23-valent polysaccharide vaccine (PPV23). Serological response was evaluated 30 days post-PPV23 by antibodies against 12 serotypes covered by both PCV13 and PPV23. Seroprotection was defined as a ≥2-fold rise to a level above 1.3 µg/ml in geometric mean concentration (GMC) across all serotypes. Associations with non-responsiveness were evaluated by logistic regression. RESULTS Fifty-two virologically suppressed PLWH (median age of 50 years (IQR 44-55) and median CD4 count of 634 cells/mm3 (IQR 507-792)) were included. Forty-six percent (95 % CI 32-61, n = 24) achieved seroprotection. Serotypes 14, 18C and 19F had the highest, and serotypes 3, 4 and 6B the lowest GMCs. Pre-vaccination GMC levels less than 100 ng/ml were associated with increased odds of non-responsiveness compared to levels above 100 ng/ml (adjusted OR 8.7, 95 % CI 1.2-63.6, p = 0.0438). CONCLUSION Less than half of our study population achieved anti-pneumococcal seroprotective levels following PCV13 and PPV23 immunization. Low pre-vaccination GMC levels were associated with non-response. Further research is required to optimize vaccination strategies that achieve higher seroprotection in this high-risk group.
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Affiliation(s)
- Michaela Tinggaard
- Department of Infectious Diseases, Copenhagen University Hospital - Amager and Hvidovre, Hvidovre, Denmark.
| | - Hans-Christian Slotved
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | | | - Gitte Kronborg
- Department of Infectious Diseases, Copenhagen University Hospital - Amager and Hvidovre, Hvidovre, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Benfield
- Department of Infectious Diseases, Copenhagen University Hospital - Amager and Hvidovre, Hvidovre, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Garrido HMG, Schnyder JL, Haydari B, Vollaard AM, Tanck MWT, de Bree GJ, Meek B, Grobusch MP, Goorhuis A. Immunogenicity of the 13-valent pneumococcal conjugate vaccine followed by the 23-valent pneumococcal polysaccharide in people living with HIV on combination antiretroviral therapy. Int J Antimicrob Agents 2022; 60:106629. [PMID: 35760223 DOI: 10.1016/j.ijantimicag.2022.106629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 06/07/2022] [Accepted: 06/19/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND People living with HIV (PLWH) are at increased risk of pneumococcal infections compared with the general population. The objective of this study was to investigate the immunogenicity of the combined pneumococcal vaccination schedule in PLWH. METHODS In this prospective cohort study, adult PLWH on antiretroviral therapy and HIV negative controls received the 13-valent pneumococcal conjugate vaccine (PCV13) at baseline followed by the 23-valent polysaccharide vaccine (PPSV23) at month 2. Serotype-specific IgG levels of 24 vaccine serotypes were measured (months 0, 2, 4, 6, 12). The primary outcome was seroprotection at month 4, defined as the proportion of patients with a post-immunization IgG concentration of ≥1.3 µg/mL for ≥70% (17/24) of vaccine serotypes. FINDINGS Samples of 120 patients were analysed. Seroprotection at month 4 was 49% (39/80) for PLWH and 82% (28/34) in controls. At month 12, seroprotection had decreased to 23% (18/79) and 63% (22/35), respectively. Nadir CD4 counts ≥ 200 cells/mm3, preserved kidney function and co-administration of the diphtheria-tetanus-polio (DTP) vaccine were associated with better seroprotection among PLWH. IgG levels of both PLWH and controls (all 24 vaccine serotypes) were significantly higher compared with baseline at all timepoints. INTERPRETATION Although IgG levels of all 24 vaccine serotypes increased significantly in both PLWH and controls, only a minority of PLWH achieved seroprotection after PCV13 followed by PPSV23. In addition, protective immunity waned rapidly. Further research into alternative vaccinations strategies for PLWH is needed, such as vaccination schedules with higher-valent pneumococcal vaccines. The DTP vaccine may augment pneumococcal vaccination responses.
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Affiliation(s)
- Hannah M Garcia Garrido
- Amsterdam UMC, Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands.
| | - Jenny L Schnyder
- Amsterdam UMC, Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
| | - Beheshta Haydari
- Amsterdam UMC, Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
| | - Albert M Vollaard
- Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Michael W T Tanck
- Amsterdam UMC, Department of Epidemiology and Data Science, University of Amsterdam, Amsterdam, The Netherlands
| | - Godelieve J de Bree
- Amsterdam UMC, Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
| | - Bob Meek
- St. Antonius Hospital, Department of Medical Microbiology and Immunology, Nieuwegein, the Netherlands
| | - Martin P Grobusch
- Amsterdam UMC, Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
| | - Abraham Goorhuis
- Amsterdam UMC, Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
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Garrido HM, Schnyder JL, Tanck MW, Vollaard A, Spijker R, Grobusch MP, Goorhuis A. Immunogenicity of pneumococcal vaccination in HIV infected individuals: A systematic review and meta-analysis. EClinicalMedicine 2020; 29-30:100576. [PMID: 33294820 PMCID: PMC7695973 DOI: 10.1016/j.eclinm.2020.100576] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The objective of this systematic review and meta-analysis was to summarise the literature regarding the immunogenicity of pneumococcal conjugate vaccines (PCV) and pneumococcal polysaccharide vaccines (PPSV) in adult people living with HIV (PLWH) in the era of advanced combination antiretroviral therapy (cART). METHODS The systematic review protocol was published online (PROSPERO ID: CRD 42020153137). We searched Medline (Ovid), EMBASE (Ovid), and the Global Health Library for publications from 2000 to June 11, 2020. We included all studies in adult PLWH that reported vaccine immunogenicity outcomes. The primary outcome was seroconversion rate (SCR) after PCV, PPSV and PCV/PPSV combined. For random-effects meta-analysis, we included studies defining SCR as a ≥ 2-fold increase in IgG from baseline, and reporting SCR for serotypes 6B, 14, or overall SCR, 1-3 months after vaccination. FINDINGS Our search identified 1597 unique studies, of which 115 were eligible for full-text assessment. Of these, 39 met the inclusion criteria (11 RCTs; 28 cohort studies). A high degree of heterogeneity was observed. Nineteen studies were included in the meta-analysis. Pooled overall SCRs were 42% (95% CI 30-56%), 44% (95% CI 33-55%) and 57% (95% CI 50-63%) for PLWH who received PPSV, PCV or a combination of PCV/PPSV, respectively. Compared to PPSV alone, a combination of PCV/PPSV yielded higher SCRs (OR 2.24 95% CI 1.41- 3.58), whereas we did not observe a significant difference in SCR between PCV and PPSV23 alone. There were no statistically significant differences in geometric mean post-vaccination antibody concentrations between vaccination schedules. Vaccination at higher CD4 cell counts improved immunogenicity in 8/21 studies, especially when PCV was administered. No studies assessed the long-term immunogenicity of PCV followed by PPSV23. Quality of evidence ranged from poor (n = 19) to good quality (n = 7). A limited number of pneumococcal serotypes was assessed in the majority of studies. INTERPRETATION We show that the recommended immunisation schedule consisting of a combination of PCV13/PPSV23, is immunogenic in PLWH in the era of advanced cART. However, the durability of this vaccination schedule remains unknown and must be addressed in future research. Vaccination with PCV should be delayed until immunological recovery (CD4>200) in recently diagnosed PLWH for optimal immunogenicity. The evidence gathered here supports wide implementation of the combination of PCV/PPSV23 for all PLWH. We recommend reassessment of this strategy once higher-valent PCVs become available. FUNDING HMGG is funded by a public research grant of ZonMw (project number 522004005).
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Affiliation(s)
- Hannah M.Garcia Garrido
- Centre of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam Infection & Immunity, Amsterdam Public Health, Amsterdam University Medical Centres (AUMC), Meibergdreef 9, Amsterdam, AZ 1105, The Netherlands
| | - Jenny L. Schnyder
- Centre of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam Infection & Immunity, Amsterdam Public Health, Amsterdam University Medical Centres (AUMC), Meibergdreef 9, Amsterdam, AZ 1105, The Netherlands
| | - Michael W.T. Tanck
- Amsterdam UMC, University of Amsterdam, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands
| | - Albert Vollaard
- Center for Infectious Disease Control Netherlands, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, Bilthoven, The Netherlands
| | - René Spijker
- Academic Medical Centre, University of Amsterdam, Medical Library, Amsterdam Public Health, Amsterdam, The Netherlands
- Cochrane Netherlands, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, The Netherlands
| | - Martin P. Grobusch
- Centre of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam Infection & Immunity, Amsterdam Public Health, Amsterdam University Medical Centres (AUMC), Meibergdreef 9, Amsterdam, AZ 1105, The Netherlands
| | - Abraham Goorhuis
- Centre of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam Infection & Immunity, Amsterdam Public Health, Amsterdam University Medical Centres (AUMC), Meibergdreef 9, Amsterdam, AZ 1105, The Netherlands
- Corresponding author.
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Chilson E, Scott DA, Schmoele-Thoma B, Watson W, Moran MM, Isturiz R. Immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine in patients with immunocompromising conditions: a review of available evidence. Hum Vaccin Immunother 2020; 16:2758-2772. [PMID: 32530360 PMCID: PMC7746253 DOI: 10.1080/21645515.2020.1735224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Immunocompromising conditions increase the risk of invasive pneumococcal disease (IPD). Vaccine uptake in patients with these conditions may be low in part because of concerns about decreased immunogenicity and safety in these high-risk groups. We conducted a literature search to identify publications describing antibody responses to 13-valent pneumococcal conjugate vaccine (PCV13) in immunocompromised individuals recommended for PCV13 vaccination by the US Advisory Committee on Immunization Practices (ACIP). This review summarizes immunogenicity data from 30 publications regarding the use of PCV13 comprising 2406 individuals considered at high risk for IPD by the ACIP. Although antibody responses to PCV13 in individuals with immunocompromising and high-risk conditions were variable and generally lower compared with healthy controls, the vaccine was immunogenic and was largely well tolerated. Based on these findings, concerns regarding immunogenicity and safety of PCV13 are not supported and should not be barriers to vaccination in high-risk populations.
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Affiliation(s)
- Erica Chilson
- Vaccine Medical Development & Scientific/Clinical Affairs, Pfizer Inc , Collegeville, PA, USA
| | - Daniel A Scott
- Vaccine Clinical Research and Development, Pfizer Inc , Collegeville, PA, USA
| | | | - Wendy Watson
- Vaccine Clinical Research and Development, Pfizer Inc , Collegeville, PA, USA
| | - Mary M Moran
- Vaccine Medical Development & Scientific/Clinical Affairs, Pfizer Inc , Collegeville, PA, USA
| | - Raul Isturiz
- Vaccine Medical Development & Scientific/Clinical Affairs, Pfizer Inc , Collegeville, PA, USA
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Happe M, Samuvel DJ, Ohtola JA, Korte JE, Westerink MAJ. Race-related differences in functional antibody response to pneumococcal vaccination in HIV-infected individuals. Vaccine 2019; 37:1622-1629. [PMID: 30797636 PMCID: PMC6428581 DOI: 10.1016/j.vaccine.2019.01.084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 01/11/2019] [Accepted: 01/28/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Both HIV positivity and African American (AA) ethnicity are associated with increased incidence of invasive pneumococcal disease (IPD). Poor immune response to pneumococcal polysaccharide-based vaccines may contribute to the race related increased frequency of IPD in African American HIV positive individuals. METHODS Caucasian and AA HIV-infected (HIV+) individuals 40-65 years old with CD4+ T cells/µl (CD4) >200 on antiretroviral therapy (ART) received either the 13-valent pneumococcal conjugate vaccine (PCV) followed by the 23-valent pneumococcal polysaccharide vaccine (PPV) or PPV only. Serum IgG, IgM and opsonophagocytic antibody responses to serotypes 14 and 23F as well as serum IgG and opsonophagocytic antibody responses to serotype 19A were measured pre- and post-vaccination. We measured serum markers of inflammation in all participants and performed single cell gene expression profiling at the baseline by HD Biomark in Caucasians and African Americans. RESULTS There were no significant differences in pre-immunization inflammatory markers or post-vaccination IgG and IgM concentrations between Caucasian and African American participants. However, we found significantly lower opsonophagocytic activity in response to serotypes 14 and 19A in the AA group compared to the Caucasian group. There was no association between inflammatory markers and immune response to vaccination, however we found extensive biomodal variation in gene expression levels in single IgM+ memory B cells. Differentially expressed genes may be related to differences in the immune response between ethnic groups. CONCLUSIONS Distinct racial differences were found in the functional immune response following either PPV and/or PCV/PPV immunization in HIV-positive adults, although these differences were serotype dependent. Decreased ability to respond to vaccination may in part explain racial disparities in pneumococcal disease epidemiology. ClinicalTrials.gov ID: NCT03039491.
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Affiliation(s)
- Myroslawa Happe
- Department of Immunology and Microbiology, Medical University of South Carolina, 96 Jonathan Lucas St, CSB 927, Charleston, SC 29425, United States.
| | - Devadoss J Samuvel
- Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina, 96 Jonathan Lucas St, CSB 927, Charleston, SC 29425, United States.
| | - Jennifer A Ohtola
- Department of Medicine, University of Toledo College of Medicine & Life Sciences, 3000 Arlington Ave, Toledo, OH 43614, United States.
| | - Jeff E Korte
- Department of Public Health Sciences, 135 Cannon St, Charleston, SC 29425, United States.
| | - M A Julie Westerink
- Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina, 96 Jonathan Lucas St, CSB 927, Charleston, SC 29425, United States; Department of Medicine, Ralhp H. Johnson Veterans Administration Medical Center, 109 Bee Street, Charleston, SC 29401, United States.
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6
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Licciardi PV, Tan EL, Li P, Ng OT. Pneumococcal vaccination for HIV-infected individuals in Singapore. PROCEEDINGS OF SINGAPORE HEALTHCARE 2019. [DOI: 10.1177/2010105818773773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Susceptibility to infections with pneumococcal bacteria ( Streptococcus pneumoniae) is substantially higher among human immunodeficiency virus (HIV)-infected individuals, and accounts for a significant burden of morbidity and healthcare costs. Pneumococcal vaccination is recommended in most countries for HIV-infected adults. Current policy in Singapore and Australia recommends the use of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) as a booster dose following the use of 13-valent pneumococcal conjugate vaccine (PCV13). Despite this, adherence to this policy has been suboptimal in Singapore. This may be related to the fact that PPSV23 has not been shown to have any impact on pneumococcal carriage (the necessary prerequisite for disease development). PPSV23 has also been associated with immune hyporesponsiveness, raising concerns over the use of this vaccine globally and, in particular, in high-risk populations. The lack of data from studies comparing PCV13 and PPSV23 has also contributed to the suboptimal uptake of pneumococcal vaccines by healthcare professionals for HIV-infected individuals. This review article discusses the key issues and importance of rigorous pneumococcal vaccination programmes for HIV-infected individuals. Current recommendations for pneumococcal vaccination of HIV-infected individuals in Singapore should be adopted more readily to reduce the burden of pneumococcal disease in this high-risk group.
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Affiliation(s)
- Paul V Licciardi
- Pneumococcal Research Group, Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Australia
| | - Eng Lee Tan
- Centre for Biomedical & Life Sciences, Singapore Polytechnic, Singapore
- Department of Paediatrics, University Children’s Medical Institute, National University Hospital, Singapore
| | - Peng Li
- Centre for Biomedical & Life Sciences, Singapore Polytechnic, Singapore
| | - Oon Tek Ng
- Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore
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Papadatou I, Tzovara I, Licciardi PV. The Role of Serotype-Specific Immunological Memory in Pneumococcal Vaccination: Current Knowledge and Future Prospects. Vaccines (Basel) 2019; 7:E13. [PMID: 30700048 PMCID: PMC6466264 DOI: 10.3390/vaccines7010013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/30/2018] [Accepted: 01/28/2019] [Indexed: 12/19/2022] Open
Abstract
Streptococcus pneumoniae (S. pneumoniae, pneumococcus) is a major cause of morbidity and mortality worldwide. Achieving long-term immunity against S. pneumoniae through immunization is an important public health priority. Long-term protection after immunization is thought to rely both on protective serum antibody levels and immunological memory in the form of antigen-specific memory B cells (MBCs). Although the ability to achieve protective antibody levels shortly after pneumococcal vaccination has been well documented for the various infant immunization schedules currently in use worldwide, the examination of immunological memory in the form of antigen-specific MBCs has been much more limited. Such responses are critical for long-term protection against pneumococcal colonization and disease. This review summarizes the published literature on the MBC response to primary or booster immunization with either pneumococcal polysaccharide vaccine (PPV23) or pneumococcal conjugate vaccines (PCVs), aiming to elucidate the immunological mechanisms that determine the magnitude and longevity of vaccine protection against pneumococcus. There is evidence that PCVs induce the production of antigen-specific MBCs, whereas immunization with PPV23 does not result in the formation of MBCs. Increased understanding of the immunological factors that facilitate the induction, maintenance and recall of MBCs in response to pneumococcal vaccination could enable the use of MBC enumeration as novel correlates of protection against S. pneumoniae. Ongoing studies that examine MBC response to pneumococcal vaccination in high burden settings will be extremely important in our understanding of long-term protection induced by pneumococcal conjugate vaccines.
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Affiliation(s)
- Ioanna Papadatou
- Immunobiology and Vaccinology Research Laboratory, First Department of Paediatrics, Aghia Sofia Children's Hospital, National and Kapodistrian University of Athens, 111527 Athens, Greece.
| | - Irene Tzovara
- Immunobiology and Vaccinology Research Laboratory, First Department of Paediatrics, Aghia Sofia Children's Hospital, National and Kapodistrian University of Athens, 111527 Athens, Greece.
| | - Paul V Licciardi
- Murdoch Children's Research Institute, Melbourne, VIC 3052, Australia.
- Department of Paediatrics, University of Melbourne, Parkville, Melbourne, VIC 3010, Australia.
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Liang Q, Li GF, Zhu FC. Vaccine profile of PPV23: Beijing Minhai Biotech 23-valent pneumococcal vaccine. Expert Rev Vaccines 2016; 15:1351-1359. [PMID: 27686267 DOI: 10.1080/14760584.2016.1239536] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Introduction: Diseases caused by Streptococcus pneumoniae are a major public health problem worldwide, which can be effectively prevented by the 23-valent pneumococcal polysaccharide vaccines (PPV23).Areas covered: The Beijing Minhai PPV23 showed good safety and immunogenicity profiles in clinical trials. The immunogenicity of Beijing Minhai PPV23 was non-inferior to other licensed PPVs. Although PPV23 has been proved to be highly efficient and cost-effective, and was recommended for vaccination in high-risk populations in industrialized countries, the coverage of PPV23 vaccination was relatively low in developing countries.Expert commentary: The low vaccination proportions of PPV23 in China have not been improved in recent decades. Most of the populations with indications for receiving PPV23 were not aware of the possible benefits of PPV23. Moreover, PPV23 had some limitations, which called for the development of a new generation of vaccines against pneumococcal infection.
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Affiliation(s)
- Qi Liang
- Jiangsu Provincial Center for Disease Control and Prevention, Vaccine Clinical Evaluation Department, Nanjing, PR China
| | - Gui-Fan Li
- Beijing Minhai Biotechnology Co. Ltd, Beijing, PR China
| | - Feng-Cai Zhu
- Jiangsu Provincial Center for Disease Control and Prevention, Vaccine Clinical Evaluation Department, Nanjing, PR China
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