Cost-effectiveness analysis of vaccination strategies against meningococcal disease for children under nine years of age in China

Meningococcal vaccination strategies in China are intricate, including multiple vaccines targeting different serogroups. The current National Immunization Program (NIP) includes two polysaccharide vaccines for serogroups A and C (MPV-A and MPV-AC), covering limited serogroups and requiring adaptation. This study aims to evaluate the cost-effectiveness of replacing the current strategy with alternative strategies utilizing non-NIP vaccines to inform policy decisions. From a societal perspective, a decision tree-Markov model was constructed to simulate the economic and health consequences of meningococcal disease in a 2019 birth cohort with four vaccination strategies. Epidemiology, vaccine efficacy, cost, and other parameters were derived from previous studies. We conducted sensitivity analyses to assess the robustness of the findings and explored prices for non-NIP vaccines that enable cost-effective strategies. Compared to the current strategy, alternative strategies using quadrivalent polysaccharide vaccine (MPV-4), bivalent conjugate vaccine (MCV-AC), and quadrivalent conjugate vaccine (MCV-4) could avoid 91, 286, and 455 more meningococcal cases. The ICERs were estimated at approximately $250 thousand/QALY, $450 thousand/QALY, and $1.5 million/QALY, all exceeding the threshold of three times GDP per capita. The alternative strategies were not cost-effective. However, if vaccine prices were reduced to $3.9 for MPV-4, $9.9 for MCV-AC, and $12 for MCV-4, the corresponding strategy would be cost-effective. The current meningococcal vaccination strategy in China could effectively prevent the disease at a low cost, but with limited serogroup coverage. Strategies using MPV-4, MCV-AC, or MCV-4 could increase health benefits at a substantial cost, and might become cost-effective if vaccine prices decrease.

Introduction of the pneumococcal conjugate vaccine in humanitarian and fragile contexts: Perspectives from stakeholders in four African countries

Childhood pneumonia causes a significant burden of preventable child morbidity and mortality in Chad, Guinea, Somalia/Somaliland, and South Sudan. Leaders from these countries have committed to reducing this burden and are preparing to introduce the pneumococcal conjugate vaccine (PCV) into their immunization programs. To support long-term sustainability for expected PCV introductions in settings afflicted by prolonged humanitarian crises this research explores national stakeholders' perspectives on contextual factors that may influence optimal vaccine implementation. This qualitative study used purposive sampling to identify and interview stakeholders involved in vaccine decision-making. Interview transcripts were analyzed through the framework method, an approach involving charting data into pre-populated matrices. Findings from interviews with 16 key informants from government, partner organizations, and international health agencies fit within the following four overarching themes: (1) population-level vulnerabilities to pneumonia, exacerbated by climatic risks and low levels of maternal education; (2) disease burden and the interest in enhancing surveillance to monitor vaccine impact and integrate disease control efforts; (3) policy processes, including formalizing vaccine decision-making; and (4) vaccine implementation preparation, including the conduct of robust communication campaigns, training, and cold chain upgrades. This research explores perspectives from leaders in these countries which are at pivotal moments in their journeys toward introducing PCV. Widespread commitment among leaders, in addition to financial support, will facilitate vaccine introduction. Further, fostering a shared understanding among partners about context-specific determinants of program success will help build tailored implementation strategies for each country.

A phase 3, single-arm, open-label study to evaluate the safety, tolerability, and immunogenicity of a 15-valent pneumococcal conjugate vaccine, V114, in a 3+1 regimen in healthy infants in South Korea (PNEU-PED-KOR)

There is an ongoing burden of pneumococcal disease in children despite the use of pneumococcal conjugate vaccines (PCVs). This phase 3, open-label, single-arm, multisite, descriptive study was designed to evaluate the safety and immunogenicity of a 3 + 1 regimen of V114 (VAXNEUVANCE™), a 15-valent PCV, in South Korean infants and toddlers. Adverse events (AEs) were reported for 14 d following any vaccination, and throughout the study period for serious AEs. Serotype-specific immunoglobulin G (IgG) response rates (proportion of participants meeting an IgG threshold value of ≥0.35 μg/mL) and geometric mean concentrations (GMCs) for the 15 serotypes at 30 d postdose 3 (PD3) and at 30 d postdose 4 (PD4) were evaluated as endpoints. Healthy infants enrolled at 42-90 d after birth were vaccinated with V114 (N = 57). The most commonly reported AEs were those solicited in the trial. The majority of reported AEs were transient and of mild or moderate intensity. Few serious AEs were reported; none were vaccine related. No participants died nor discontinued the study vaccine because of an AE. V114 was immunogenic for all 15 serotypes contained in the vaccine, as assessed by IgG response rates at 30 d PD3 and IgG GMCs at 30 d PD3 and at 30 d PD4. V114 was well tolerated and immunogenic when administered as a 3 + 1 regimen in healthy South Korean infants and toddlers.

COT-TT vaccine attenuates cocaine-seeking and cocaine-conditioned place preference in rats

Vaccination active, promising alternative immunological strategy to treat of CUD. Various models of cocaine vaccines have been evaluated in animals and humans with relative success. In this sense, it is necessary to improve or optimize the cocaine vaccines already evaluated. Our laboratory previously reported the efficacy of the tetanus toxoid-conjugated morphine vaccine (M6-TT). The M6-TT vaccine can generate high titers of antibodies and reduce heroin-induced behavioral effects in rodents. So, it would be plausible to assume that if we modify the M6-TT vaccine by changing the hapten and maintaining the rest of the structural elements of the vaccine, we will maintain the properties of the M6-TT vaccine (high antibody titers). The objective of this study was to determine whether the antibodies generated by a tetanus toxoid-conjugated cocaine vaccine (COC-TT) can recognize and capture cocaine and decrease the cocaine-induced reinforcing effects. Male Wistar rats were immunized with the COC-TT. A solid-phase antibody-capture ELISA was used to monitor antibody titer responses after each booster dose in vaccinated animals. The study used cocaine self-administration and place-preference testing to evaluate the cocaine-reinforcing effects. The COC-TT vaccine could generate high levels of anti-cocaine antibodies. The antibodies reduced the cocaine self-administration and cocaine place preference. In addition, they decreased the cocaine-induced Fos protein expression. These findings suggest that the COC-TT vaccine generates a robust immunogenic response capable of reducing the reinforcing effects of cocaine, which supports its possible future use in clinical trials in patients with CUD.

Strategies for pneumococcal vaccination in older adults in the coming era

Pneumonia, predominantly caused by Streptococcus pneumoniae, remains a leading cause of global mortality. The 23-valent Pneumococcal polysaccharide vaccine (PPSV23) and conjugate vaccines (PCVs) are vital measures to fight against it. This paper discussed the changes in pneumococcal vaccination strategies, particularly for older adults, as vaccine effectiveness and epidemiological patterns shift. While PPSV23 maintains effectiveness against invasive pneumococcal disease (IPD), its effectiveness against pneumococcal pneumonia is declining. Conversely, PCV13 consistently demonstrates effectiveness against both IPD and pneumonia. Consequently, the US Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recommends using PCVs, notably PCV20 and PCV15, over PPSV23. Japanese studies indicate a change in the efficacy/effectiveness of PPSV23 following PCV introduction in children, likely owing to serotype replacement and herd immunity. Additionally, recent data reveals a plateau in the reduction of PCV13 and PPSV23-covered serotypes, posing a challenge to current strategies. This paper indicates a paradigm shift in pneumonia management, acknowledging its chronic nature and potential to exacerbate other diseases. The future of pneumococcal vaccination lies in broader serotype coverage through PCVs, adapting to serotype changes driven by childhood vaccination programs. Furthermore, continuous research and vaccine development are crucial in this evolving field.

Using big data to analyze the vaccination status of children with congenital heart disease in Yinzhou District, China

Congenital heart disease (CHD) represents a significant population warranting particular attention concerning vaccination coverage. To comprehend the vaccination status of CHD within Yinzhou District, Ningbo City, China, and to facilitate the formulation of preventive, control, and immunization strategies against vaccine-preventable diseases in children with congenital heart conditions. Using the China Yinzhou Electronic Health Record Study (CHERRY) database, we analyzed the vaccination coverage of children with CHD born between January 1, 2016 and September 20, 2021, and analyzed the influencing factors associated with the level of vaccination coverage. This study involved 762 children diagnosed with CHD at the age of 12 months, revealing that 86.74% of these children had received at least one dose of the National Immunization Program (NIP) vaccines. The coverage for non-NIP vaccines, such as the rotavirus vaccine, influenza vaccine, Influenza Haemophilus influenzae Type b (Hib) Conjugate Vaccine, 13-valent pneumococcal conjugate vaccine (PCV13), and inactivated enterovirus type 71 vaccine (EV71), stood at 27.30%, 7.74%, 63.25%, 33.76%, and 34.51%, respectively. The completion coverage for the entire vaccination schedule were 27.30%, 5.51%, 55.77%, 34.25%, and 25.59%, respectively. There was a statistically significant correlation between vaccination coverage in classification of diagnostic medical institutions and the types of diagnosed diseases. Compared to their typically developing counterparts, 12-month-old children afflicted with CHD exhibit a slightly diminished vaccination coverage, alongside a discernible inclination toward delayed vaccination. Notably, the determination to undergo vaccinations seems predominantly influenced by the classification of diagnostic medical institutions. In practical terms, proactive measures involving early diagnosis, comprehensive health assessments, and timely interventions ought to be implemented to enhance vaccination rates while prioritizing safety.

Understanding healthcare providers' preferred attributes of pediatric pneumococcal conjugate vaccines in the United States

As higher-valent pneumococcal conjugate vaccines (PCVs) become available for pediatric populations in the US, it is important to understand healthcare provider (HCP) preferences for and acceptability of PCVs. US HCPs (pediatricians, family medicine physicians and advanced practitioners) completed an online, cross-sectional survey between March and April 2023. HCPs were eligible if they recommended or prescribed vaccines to children age <24 months, spent ≥25% of their time in direct patient care, and had ≥2 y of experience in their profession. The survey included a discrete choice experiment (DCE) in which HCPs selected preferred options from different hypothetical vaccine profiles with systematic variation in the levels of five attributes. Relative attribute importance was quantified. Among 548 HCP respondents, the median age was 43.2 y, and the majority were male (57.9%) and practiced in urban areas (69.7%). DCE results showed that attributes with the greatest impact on HCP decision-making were 1) immune response for the shared serotypes covered by PCV13 (31.4%), 2) percent of invasive pneumococcal disease (IPD) covered by vaccine serotypes (21.3%), 3) acute otitis media (AOM) label indication (20.3%), 4) effectiveness against serotype 3 (17.6%), and 5) number of serotypes in the vaccine (9.5%). Among US HCPs, the most important attribute of PCVs was comparability of immune response for PCV13 shared serotypes, while the number of serotypes was least important. Findings suggest new PCVs eliciting high immune responses for serotypes that contribute substantially to IPD burden and maintaining immunogenicity against serotypes in existing PCVs are preferred by HCPs.

State of pneumococcal vaccine immunity

Like the other invasive encapsulated bacteria, Streptococcus pneumoniae is also covered with a polysaccharide structure. Infants and elderly are most vulnerable to the invasive and noninvasive diseases caused by S. pneumoniae. Although antibodies against polysaccharide capsule are efficient in eliminating S. pneumoniae, the T cell independent nature of the immune response against polysaccharide vaccines renders them weakly antigenic. The introduction of protein conjugated capsular polysaccharide vaccines helped overcome the weak immunogenicity of pneumococcal polysaccharides and decreased the incidence of pneumococcal diseases, especially in pediatric population. Conjugate vaccines elicit T cell dependent response which involve the interaction of specialized CD4+ T cells, called follicular helper T cells (Tfh) with germinal center B cells in secondary lymphoid organs. Despite their improved immunogenicity, conjugate vaccines still need to be administered three to four times in infants during the first 15 month of their life because they mount poor Tfh response. Recent studies revealed fundamental differences in the generation of Tfh cells between neonates and adults. As the portfolio of pneumococcal conjugate vaccines continues to increase, better understanding of the mechanisms of antibody development in different age groups will help in the development of pneumococcal vaccines tailored for different ages.

Development and validation of a 6-plex Luminex-based assay for measuring human serum antibodies to group B streptococcus capsular polysaccharides

Six serotypes (Ia, Ib, II, III, IV, and V) cause nearly all group B streptococcal (GBS) disease globally. Capsular polysaccharide (CPS) conjugate vaccines aim to prevent GBS disease, however, licensure of a vaccine would depend on a standardized serological assay for measuring anti-CPS IgG responses. A multiplex direct Luminex-based immunoassay (dLIA) has been developed to simultaneously measure the concentration of serum IgG specific for the six prevalent GBS CPS serotypes. Assay validation was performed using serum samples obtained from human subjects vaccinated with an investigational 6-valent GBS CPS conjugate vaccine. Results for the assay are expressed as IgG concentrations (µg/mL) using a human serum reference standard composed of pooled sera from vaccinated subjects. The lower limits of quantitation (LLOQ) for all serotypes covered in the 6-plex GBS IgG dLIA fell within the range of 0.002-0.022 µg/mL IgG. Taken together, the 6-plex GBS IgG dLIA platform is specific for the six GBS serotypes included in Pfizer's investigational vaccine, has a wide dilution adjusted assay range, and is precise (<18.5% relative standard deviation) for all serotypes, and, therefore, is suitable for quantitatively measuring vaccine-induced or naturally acquired serotype-specific anti-CPS IgG responses against GBS.

Global, Regional, and National Burdens of Otitis Media From 1990 to 2019: A Population Based Study

OBJECTIVES

Otitis media is one of the most important causes of hearing loss at an early age. Effective vaccination with the routine 7-valent pneumococcal conjugate vaccine (PCV-7) was introduced in 2000. It has been gradually replaced by the pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine or the higher-valent 13-valent PCV (PCV-13) since 2010. Data on the change in otitis media burden in recent years are sparse at the global, regional, and national levels.

DESIGN

The Global Burden of Disease 2019 study was used to evaluate the prevalence, incidence, mortality, disability-adjusted life year (DALY) rates, and the average annual percentage changes (AAPCs) in otitis media in geographic populations worldwide from 1990 to 2019. These global trends were further analyzed by subgroup (age, sex, and sociodemographic index [SDI]).

RESULTS

Globally, the all-age rate of prevalence (AAPC = -0.7, 95% confidence interval [CI] = -0.7 to -0.8), DALYs (AAPC = -1.0, 95% CI = -1.1 to -1.0), and mortality (AAPC = -6.8, 95% CI = -7.3 to -6.4) from otitis media decreased constantly between 1990 and 2019. The all-age rate of incidence decreased sharply between 2000 and 2009 with an AAPC of -1.2 (95% CI = -1.4 to -0.9) and continued the downward trend between 2010 and 2019 (AAPC = -0.2, 95% CI = -0.3 to -0.1). In 2019, children aged 1 to 4 years old had the highest incidence at 29,127.3 per 100,000 population, while young adults under 30 years old accounted for 91.3% of the incident cases. Individuals living in middle-SDI countries had the largest increase in the incidence of otitis media, with an AAPC of 0.3 (95% CI = 0.3 to 0.3) between 1990 and 2019. The incidence and DALYs from otitis media decreased with increasing SDI. Regionally, the largest increase in incidence was observed in high-income Asia Pacific, Eastern Europe, and Western Sub-Saharan Africa between 1990 and 2019. Nationally, the largest increase in the incidence of otitis media was observed in the Republic of Korea, with an AAPC of 0.8 (95% CI = 0.6 to 1.1) in the same time period.

CONCLUSIONS

There have been successful previous endeavors to reduce DALYs and mortality attributed to otitis media on a global scale. The worldwide incidence of otitis media experienced a sharp decline following the introduction of PCV-7 in 2000, and this downward trend persisted in subsequent years with the adoption of PCV-13/pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine. Continual epidemiological surveillance of otitis media's global trends, pathogen distribution, and resistance patterns remains imperative.

Nurses' preferences regarding MenACWY conjugate vaccines attributes: a discrete choice experiment in Spain

OBJECTIVES

Immunisation against preventable diseases as meningitis is crucial from a public health perspective to face challenges posed by these infections. Nurses hold a great responsibility for these programs, which highlights the importance of understanding their preferences and needs to improve the success of campaigns. This study aimed to investigate nurses' preferences regarding Meningococcus A, C, W, and Y (MenACWY) conjugate vaccines commercialised in Spain.

STUDY DESIGN

A national-level discrete choice experiment (DCE) was conducted.

METHODS

A literature review and a focus group informed the DCE design. Six attributes were included: pharmaceutical form, coadministration evidence, shelf-life, package contents, single-doses per package, and package volume. Conditional logit models quantified preferences and relative importance (RI).

RESULTS

Thirty experienced primary care nurses participated in this study. Evidence of coadministration with other vaccines was the most important attribute (RI = 43.78%), followed by package size (RI = 22.17%), pharmaceutical form (RI = 19.07%), and package content (RI = 11.80%). There was a preference for evidence of coadministration with routine vaccines (odds ratio [OR] = 2.579, 95% confidence interval [95%CI] = 2.210-3.002), smaller volumes (OR = 1.494, 95%CI = 1.264-1.767), liquid formulations (OR = 1.283, 95%CI = 1.108-1.486) and package contents including only vial/s (OR = 1.283, 95%CI = 1.108-1.486). No statistical evidence was found for the remaining attributes.

CONCLUSIONS

Evidence of coadministration with routine vaccines, easy-to-store packages, and fully liquid formulations were drivers of nurses' preferences regarding MenACWY conjugate vaccines. These findings provide valuable insights for decision-makers to optimize current campaigns.

Protective effect of PCV13 against all-cause hospitalized pneumonia in children in Beijing, China: real-world evidence

BACKGROUND

The study evaluated the protective effect of 13-valent pneumococcal polysaccharide conjugate vaccine (PCV13) against all-cause hospitalized pneumonia in children in Beijing.

METHODS

Based on the vaccination record and inpatient medical record database of Beijing, children born in 2017 in Beijing, matched by age, gender, and district of the children with the ratio of 1:4, were selected as the vaccinated and unvaccinated groups according whether if vaccinated with PCV13. The incidence rate and 95 % confidence interval (95 %CI), vaccine effectiveness (VE) and direct medical costs of all-cause hospitalized pneumonia were calculated and compared within the same period of 12 months, 18 months, 24 months and 30 months after the birth of the child.

RESULTS

The decreased incidence rates of all-cause hospitalized pneumonia were observed at the four points in the PCV13 vaccinated group compared to the unvaccinated group, which were significant at the points of 12 months (0.42 % vs. 0.72 %, P = 0.001), 18 months (0.90 % vs. 1.26 %, P = 0.002) and 24 months (1.37 % vs. 1.65 %, P = 0.046). The VE of PCV13 against all-cause hospitalized pneumonia within 12 months was the highest as 41.9 % (95 % CI 19.6 %, 58.0 %), followed by 29.3 % (95 % CI 11.4 %, 43.5 %) within 18 months, 17.1 % (95 % CI 0.3 %, 31.1 %) within 24 months and it almost disappeared within 30 months. The VE of 4-dose vaccination within 18 months and 24 months were 39.9 % (95 % CI 20.3 %, 54.7 %) and 27.2 % (95 % CI 8.6 %, 42.0 %), respectively. The median hospitalization cost of the children in the vaccinated group was higher at the four points but without significance.

CONCLUSIONS

PCV13 had a certain protective effect on all-cause hospitalized pneumonia, and the booster immunization strategy had the best protective effect with great public health significance to enter the immunization program.

Immunogenicity and safety of adsorbed diphtheria-purified pertussis-tetanus-inactivated polio (Sabin strain)-Haemophilus type b conjugate combined vaccine (DPT-IPV-Hib) in healthy Japanese Infants ≥ 2 and < 43 months of Age: A phase III, multicenter, active controlled, assessor-blinded, randomized, parallel-group study

OBJECTIVE

This study investigated the immunogenicity and safety of a pentavalent vaccine Gobik (DPT-IPV-Haemophilus influenzae type b [Hib]) in healthy Japanese infants aged ≥ 2 and < 43 months using a concomitant vaccination with ActHIB® (Hib) and Tetrabik (DPT-IPV) as a comparator.

METHODS

This study was conducted as a phase 3, multicenter, active controlled, assessor-blinded, randomized, parallel-group study. Participants received a total of 4 subcutaneous doses (3 primary immunization doses and a booster dose) of either the experimental drug (DPT-IPV-Hib) or the active comparator (Hib + DPT-IPV). The primary endpoints were the anti-PRP antibody prevalence rate with ≥ 1 μg/mL, and the antibody prevalence rates against pertussis, diphtheria toxin, tetanus toxin, and attenuated poliovirus after the primary immunization.

RESULTS

In 267 randomized participants (133 in the DPT-IPV-Hib group and 134 in the Hib + DPT-IPV group), the antibody prevalence rates after the primary immunization in both groups were 100.0 % and 88.7 % for anti-PRP antibody with ≥ 1 μg/mL, 99.2 % and 98.5 % against diphtheria toxin, and 100.0 % and 99.2 % against tetanus toxin, respectively. The antibody prevalence rates against pertussis and attenuated poliovirus were 100.0 % in both groups. The non-inferiority of the DPT-IPV-Hib group to the Hib + DPT-IPV group was verified for all measured antibodies. In both groups, all the GMTs of antibodies after the primary immunization were higher than those before the first dose, and those after the booster dose were higher than those after the primary immunization. No safety issues were identified.

CONCLUSION

A single-agent Gobik, the first DPT-IPV-Hib pentavalent vaccine approved in Japan, was confirmed to simultaneously provide primary and booster immunizations against Hib infection, pertussis, diphtheria, tetanus, and poliomyelitis and to have a preventive effect and safety comparable to concomitant vaccination with Hib (ActHIB®) and DPT-IPV quadrivalent vaccine (Tetrabik).

Uptake of pneumococcal vaccines in older Australian adults before and after universal public funding of PCV13

BACKGROUND

In 2020 Australia changed the funded universal older adult pneumococcal vaccination program from use of the 23-valent pneumococcal polysaccharide vaccine (PPV23) at age 65 to the 13-valent pneumococcal conjugate vaccine (PCV13) at age 70 years. We investigated uptake of both PCV13 and PPV23 in older adults before and after the program change.

METHODS

We analysed a national dataset of records of patients attending general practices (GPs). We included regular attendees aged 65 or above in 2020. Cumulative uptake of PCV13 and monthly uptake of PPV23 was compared for the two periods before (January 2019 to June 2020) and after (July 2020 to May 2021) the program change on 1 July 2020, by age groups and presence of comorbid conditions.

RESULTS

Our study included data from 192,508 patients (mean age in 2020: 75.1 years, 54.2 % female, 46.1 % with at least one comorbidity). Before July 2020, for all adults regardless of underlying comorbidities, the cumulative uptake of PCV13 was < 1 % but by May 2021, eleven months after the program changes, cumulative uptake of PCV13 had increased among those aged 70-79 years (without comorbidity: 16.3 %; with comorbidity: 21.1 %) and 80 + years (without comorbidity: 13.5 %; with comorbidity: 17.7 %), but not among those aged 65-69 years (without comorbidity: 1.3 %; with comorbidity: 3 %). Monthly uptake of PPV23 dropped following the program change across all age groups.

CONCLUSIONS

Changes in uptake of PCV13 and PPV23 among those aged 70 + years were consistent with program changes. However, PCV13 uptake was still substantially lower in individuals aged 65-69 years overall and in those with comorbidities.

Poor association between 13-valent pneumococcal conjugate vaccine-induced serum and mucosal antibody responses with experimental Streptococcus pneumoniae serotype 6B colonisation

BACKGROUND

Pneumococcal carriage is the primary reservoir for transmissionand a prerequisite for invasive pneumococcal disease. Pneumococcal Conjugate Vaccine 13 (PCV13) showed a 62% efficacy in protection against experimental Streptococcus pneumoniae serotype 6B (Spn6B) carriage in a controlled human infection model (CHIM) of healthy Malawian adults. We, therefore, measured humoral responses to experimental challenge and PCV-13 vaccination and determined the association with protection against pneumococcal carriage.

METHODS

We vaccinated 204 young, healthy Malawian adults with PCV13 or placebo and nasally inoculated them with Spn6B at least four weeks post-vaccination to establish carriage. We collected peripheral blood and nasal lining fluid at baseline, 4 weeks post-vaccination (7 days pre-inoculation), 2, 7, 14 and > 1 year post-inoculation. We measured the concentration of anti-serotype 6B Capsular Polysaccharide (CPS) Immunoglobulin G (IgG) and IgA antibodies in serum and nasal lining fluid using the World Health Organization (WHO) standardised enzyme-linked immunosorbent assay (ELISA).

RESULTS

PCV13-vaccinated adults had higher serum IgG and nasal IgG/IgA anti-Spn6B CPS-specific binding antibodies than placebo recipients 4 to 6 weeks post-vaccination, which persisted for at least a year after vaccination. Nasal challenge with Spn6B did not significantly alter serum or nasal anti-CPS IgG binding antibody titers with or without experimental pneumococcal carriage. Pre-challenge titers of PCV13-induced serum IgG and nasal IgG/IgA anti-Spn6B CPS binding antibodies did not significantly differ between those that got experimentally colonised by Spn6B compared to those that did not.

CONCLUSION

This study demonstrates that despite high PCV13 efficacy against experimental Spn6B carriage in young, healthy Malawian adults, robust vaccine-induced systemic and mucosal anti-Spn6B CPS binding antibodies did not directly relate to protection.

The safety and immunogenicity of a bivalent conjugate vaccine against Salmonella enterica Typhi and Paratyphi A in healthy Indian adults: a phase 1, randomised, active-controlled, double-blind trial

BACKGROUND

Enteric fever caused by Salmonella enterica Typhi and Salmonella Paratyphi A is an important public health problem, especially in low-income and middle-income countries with limited access to safe water and sanitation. We present results from, to our knowledge, the first ever human study of a bivalent paratyphoid A-typhoid conjugate vaccine (Sii-PTCV).

METHODS

In this double-blind phase 1 study, 60 healthy Indian adults were randomly assigned (1:1) to receive a single intramuscular dose of either Sii-PTCV or typhoid conjugate vaccine (Typbar-TCV). Safety was assessed by observing solicited adverse events for 1 week, unsolicited events for 1 month, and serious adverse events (SAEs) over 6 months. Immunogenicity at 1 month and 6 months was assessed by measuring anti-capsular polysaccharide antigen Vi (anti-Vi) IgG and IgA against Salmonella Typhi and anti-lipopolysaccharide (LPS) IgG against Salmonella Paratyphi A by ELISA, and functional antibodies using serum bactericidal assay (SBA) against Salmonella Paratyphi A. This study is registered with Clinical Trial Registry-India (CTRI/2022/06/043608) and is completed.

FINDINGS

60 participants were enrolled. Of these 60 participants, 57 (95%) participants were male and three (5%) participants were female. Solicited adverse events were observed in 27 (90%) of 30 participants who received Sii-PTCV and 26 (87%) of 30 participants who received Typbar-TCV. The most common local solicited event was pain in 27 (90%) participants who received Sii-PTCV and in 23 (77%) participants who received Typbar-TCV. The most common solicited systemic event was myalgia in five (17%) participants who received Sii-PTCV, whereas four (13%) participants who received Typbar-TCV had myalgia and four (13%) had headache. No vaccine-related unsolicited adverse events or SAEs were reported. The seroconversion rates on day 29 were 96·7% (95% CI 82·8-99·9) with Sii-PTCV and 100·0% (88·4-100·0) with Typbar-TCV for anti-Vi IgG; 93·3% (77·9-99·2) with Sii-PTCV and 100·0% (88·4-100·0) with Typbar-TCV for anti-Vi IgA; 100·0% (88·4-100·0) with Sii-PTCV and 3·3% (0·1-17·2) with Typbar-TCV for anti-LPS (paratyphoid); and 93·3% (77·9-99·2) with Sii-PTCV and 0% (0·0-11·6) with Typbar-TCV for SBA titres (paratyphoid). Paratyphoid anti-LPS immune responses were sustained at day 181.

INTERPRETATION

Sii-PTCV was safe and immunogenic for both typhoid and paratyphoid antigens indicating its potential for providing comprehensive protection against enteric fever.

FUNDING

Serum Institute of India.

A randomized, blind, parallel controlled phase I clinical trial to evaluate the safety and preliminary immunogenicity of 23-valent pneumococcal polysaccharide vaccine in healthy people aged 2 years and older

BACKGROUND

Despite some progress in pneumococcal immunization, the global burden of pneumococcal infection remains high, and pneumococcal disease remains a public health concern. Studies in China and abroad have found that 23-valent pneumococcal polysaccharide vaccine (PPV23) vaccination can effectively prevent invasive pneumococcal disease. This phase Ⅰ clinical study assessed the safety and immunogenicity of a PPV23 vaccine candidate.

METHODS

All subjects were randomly assigned to receive one dose intramuscular injection of experimental vaccine or control vaccine at a ratio of 1:1. The incidence of any adverse events was observed within 30 min, 0-7 days and 8-28 days post vaccination and the incidence of abnormal blood biochemical and blood routine indicators were tested on the 4th day post vaccination, the incidence of serious adverse events (SAEs) at 6 months post vaccination was recorded. Blood samples were collected prior to vaccination and on the 28th day post vaccination, and serum antibodies were detected by enzyme linked immunosorbent assay (ELISA).

RESULTS

The most common adverse reaction was pain at the injection site, followed by erythema. There was no significant difference of the incidence of systemic adverse reactions between the two vaccine groups. The adverse reactions observed in the trial were all common vaccination-related reactions, and no serious adverse reactions were observed. Compared to pre-vaccination, the (geometric mean concentrations) GMCs of IgG (immunoglobulin G) specific antibody against each serotype were all increased in the experimental group and the control group, there were statistical differences in seroconversion rates of serotypes 4 and 20 between the two vaccine groups.

CONCLUSION

This clinical study showed good safety of the PPV23 vaccine candidate produced by Ab&b Biotechnology Co., Ltd.JS had good safety after vaccination in people aged 2 years and older. At the same time, good immunogenicity was also demonstrated.

Cost-effectiveness and public health impact of typhoid conjugate vaccine introduction strategies in Bangladesh

PURPOSE

Typhoid fever causes substantial morbidity and mortality in Bangladesh. The government of Bangladesh plans to introduce typhoid conjugate vaccines (TCV) in its expanded program on immunization (EPI) schedule. However, the optimal introduction strategy in addition to the costs and benefits of such a program are unclear.

METHODS

We extended an existing mathematical model of typhoid transmission to integrate cost data, clinical incidence data, and recently conducted serosurveys in urban, semi-urban, and rural areas. In our primary analysis, we evaluated the status quo (i.e., no vaccination) and eight vaccine introduction strategies including routine and 1-time campaign strategies, which differed by age groups targeted and geographic focus. Model outcomes included clinical incidence, seroincidence, deaths, costs, disability-adjusted life years (DALYs), and incremental cost-effectiveness ratios (ICERs) for each strategy. We adopted a societal perspective, 10-year model time horizon, and 3 % annual discount rate. We performed probabilistic, one-way, and scenario sensitivity analyses including adopting a healthcare perspective and alternate model time horizons.

RESULTS

We projected that all TCV strategies would be cost saving compared to the status quo. The preferred strategy was a nationwide introduction of TCV at 9-12 months of age with a single catch-up campaign for children ages 1-15, which was cost saving compared to all other strategies and the status quo. In the 10 years following implementation, we projected this strategy would avert 3.77 million cases (95 % CrI: 2.60 - 5.18), 11.31 thousand deaths (95 % CrI: 3.77 - 23.60), and save $172.35 million (95 % CrI: -14.29 - 460.59) compared to the status quo. Our findings were broadly robust to changes in parameter values and willingness-to-pay thresholds.

CONCLUSIONS

We projected that nationwide TCV introduction with a catch-up campaign would substantially reduce typhoid incidence and very likely be cost saving in Bangladesh.

Incidence of pneumococcal disease in children ≤48 months old in the United States: 1998-2019

BACKGROUND

Pneumococcal disease (PD) is a major cause of morbidity and mortality among children, particularly in the youngest age groups. This study aimed to assess the incidence of PD over time by age group in young children with commercial or Medicaid coverage in the US.

METHODS

Episodes of invasive pneumococcal disease (IPD), all-cause pneumonia (ACP), and acute otitis media (AOM) were identified in the MarketScan® Commercial and Medicaid claims databases using diagnosis codes among children aged ≤ 48 months with confirmed date of birth (DoB), at any time during the study period (1998-2019). DoB was assigned using diagnosis codes for birth or delivery using the child's or mother's medical claims to ensure accurate age determination. Annual incidence rates (IRs) were calculated as number of disease episodes/100,000 person-years (PY) for IPD and ACP and episodes/1,000 PY for AOM, for children aged 0-6, 7-12, 12-24, and 25-48 months.

RESULTS

Annual IPD IRs declined from 53 to 7 episodes/100,000 PY between 1998 and 2019 in commercially-insured and 58 to 9 episodes/100,000 PY between 2001 and 2019 in Medicaid-insured children. Annual ACP IRs declined from 5,600 to 3,952 episodes/100,000 PY, and from 6,706 to 4,521 episodes/100,000 PY, respectively, over these periods. In both populations, children aged 0-6 months had the highest incidence of IPD and inpatient ACP. Annual AOM IRs declined from 1,177 to 738 episodes/1,000 PY (commercially-insured) and 633 to 624 episodes/1,000 PY (Medicaid-insured), over these periods. IRs were higher in rural vs. urban areas for all disease manifestations.

CONCLUSIONS

Incidence rates of IPD, ACP, and AOM decreased in children with commercial insurance and Medicaid coverage from 1998 to 2019. However, burden of disease remained substantial, with higher annual IRs for IPD and ACP for Medicaid-insured vs. commercially-insured children. IPD and inpatient ACP were most common in the youngest children 0-6 months old, followed by the 7-12-month age group.

Humoral and cellular immune responses induced by serogroup W135 meningococcal conjugate and polysaccharide vaccines

Investigating the mechanisms by which W135 meningococcal conjugate (PSW135-TT) activates adaptive immune responses in mice can provide a comprehensive understanding of the immune mechanisms of bacterial polysaccharide conjugate vaccines. We compared B-cell and T-cell immune responses immunized with W135 meningococcal capsular polysaccharides (PSW135), tetanus toxoid (TT) and PSW135-TT in mice. The results showed that PSW135-TT could induce higher PSW135-specific and TT-specific IgG antibodies with a significant enhancement after two doses. All serum antibodies immunized with PSW135- TT had strong bactericidal activity, whereas none of the serum antibodies immunized with PSW135 had bactericidal activity. Besides, IgM and IgG antibodies immunized with PSW135-TT after two doses were positively correlated with the titer of bactericidal antibodies. We also found Th cells favored Th2 humoral immune responses in PSW135-TT, PSW135, and TT-immunized mice, especially peripheral blood lymphocytes. Furthermore, PSW135-TT and TT could effectively activate bone marrow derived dendritic cells (BMDCs) and promote BMDCs to highly express major histocompatibility complex Ⅱ (MHCⅡ), CD86 and CD40 molecules in mice, whereas PSW135 couldn't. These data verified the typical characteristics of PSW135-TT and TT as T cell dependent antigen (TD-Ag) and PSW135 as T cell independent antigen (TI-Ag), which will be very helpful for further exploration of the immune mechanism of polysaccharide-protein conjugate vaccines and improvement of the quality of bacterial polysaccharide conjugate vaccines in future.

Re-N-acetylation of group B Streptococcus type Ia capsular polysaccharide improves the immunogenicity of glycoconjugate vaccines

The capsular polysaccharides (CPS) of Group B Streptococcus play a crucial role as virulence determinants and are potential candidates for antigenic components in vaccine formulations. Alkaline treatments are commonly used to extract polysaccharides owing to their efficiency and cost-effectiveness; however, they may induce the removal of N-acetyl groups from CPS. This study involved re-N-acetylation of CPS Ia to improve its biological functionality. The structural modifications and enhanced antigenicity of CPS Ia were observed after re-N-acetylation. The tetanus toxoid (TT) was conjugated with either partially de-N-acetylated or fully re-N-acetylated CPS. As a result, the conjugate containing re-N-acetylated CPS (IaReN-TT) enhanced the induction of IgG antibody levels and functional antibodies in mice. Both passive and active protection assays substantiated the superior protective efficacy of IaReN-TT, suggesting that the re-N-acetylation of CPS Ia could be a critical step in refining the immunogenic profile of glycoconjugate vaccines.

Impact of pneumococcal conjugate vaccination on pneumococcal nasopharyngeal carriage in the Gambia: Population-based cross-sectional surveys

BACKGROUND

The introduction of pneumococcal conjugate vaccines (PCV) has reduced carriage of vaccine-type (VT) pneumococci in many settings. We determined the impact of The Gambia's national PCV programme on carriage of VT pneumococci in the population.

METHODS

Seven-valent PCV (PCV7) was introduced in August 2009 without catch-up and with doses scheduled at 2, 3, 4 months of age; it was replaced by PCV13 in May 2011. We did cross-sectional carriage surveys in 2009, 2015, and 2017 in age-stratified, population-based samples. Nasopharyngeal specimens were collected and processed according to WHO guidelines. We calculated observed and adjusted prevalence ratios (PR) of VT carriage before and after PCV introduction.

FINDINGS

We enrolled 2988, 3162, and 2709 participants in 2009, 2015, and 2017 respectively. The baseline (2009) prevalence of VT pneumococcal carriage among children aged 0-4 years was 42.6 %, which declined to 14.9 % and 17.5 % in 2015 and 2017 respectively (adjPR 0.32 [95 % CI 0.27, 0.38] and 0.38 [0.31, 0.46] respectively). VT prevalence among children aged 5-14 years was 16.6 %, 15.1 %, and 15.8 % in the three surveys (2017 vs 2009, adjPR 0.70 [0.58, 0.83]). VT prevalence among 15-44 year-olds was 6.4 %, 5.7 %, and 7.1 % in the three surveys (2017 vs 2009, adjPR 0.59 [0.46, 0.75]), while in those aged ≥ 45 years it was 4.5 %, 6.5 %, and 4.5 % respectively. Non-VT carriage increased in all age-groups. Prevalent residual serotypes were 34 and 15B (age 0-4 years), 3 and 34 (age 5-14 years), and 3 and 16F (age ≥ 15 years).

CONCLUSIONS

Introduction of PCV was associated with reduced VT pneumococcal carriage in young, and older children, although with substantial residual prevalence. Persisting VT, and non-VT, carriage indicate significant, persistent transmission of pneumococci in the population.

Safety, tolerability and immunogenicity of a novel 24-valent pneumococcal vaccine in toddlers: A phase 1 randomized controlled trial

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) significantly reduced pneumococcal disease burden. Nevertheless, alternative approaches for controlling more serotypes are needed. Here, the safety, tolerability, and immunogenicity of a 24-valent (1/2/3/4/5/6A/6B/7F/8/9N/9V/10A/11A/12F/14/15B/17F/18C/19A/19F/20B/22F/23F/33F) pneumococcal vaccine based on Multiple Antigen-Presenting System (MAPS) technology (Pn-MAPS24v) was assessed in toddlers.

METHODS

In this phase 1, blinded, dose-escalation, active-controlled multicenter study conducted in the United States (September/2020-April/2022), 12-15-month-old toddlers primed with three doses of 13-valent PCV (PCV13) were randomized 3:2 to receive a single dose of one of three Pn-MAPS24v dose levels (1 μg/2 μg/5 μg per polysaccharide) or PCV13 intramuscularly. Reactogenicity (within 7 days), treatment-emergent adverse events (TEAEs, within 180 days), serious/medically attended adverse events (SAEs/MAAEs, within 180 days), and immunogenicity (serotype-specific anti-capsular polysaccharide immunoglobulin G [IgG] and opsonophagocytic activity [OPA] responses at 30 days post-vaccination) were assessed.

RESULTS

Of 75 toddlers enrolled, 74 completed the study (Pn-MAPS24v 1 μg/2 μg/5 μg: 15/14/16, PCV13: 29). Frequencies of local (60 %/67 %/31 %) and systemic events (67 %/67 %/75 %) in the Pn-MAPS24v 1 μg/2 μg/5 μg and the PCV13 (55 %, 79 %) groups were in similar ranges. TEAEs were reported by 47 %/40 %/63 % of Pn-MAPS24v 1 μg/2 μg/5 μg recipients and 52 % of PCV13 recipients. No vaccine-related SAE was reported. At 30 days post-vaccination, for each of the 13 common serotypes, ≥93 % of participants in each group had IgG concentrations ≥0.35 μg/mL; >92 % had OPA titers ≥lower limit of quantitation (LLOQ), except for serotype 1 (79 %). For 7/11 unique serotypes (2/8/9N/11A/17F/22F/33F), at all dose levels, ≥78 % of Pn-MAPS24v recipients in each group had IgG concentrations ≥0.35 μg/mL and 80 %-100 % had OPA titers ≥LLOQ.

CONCLUSIONS

In 12-15-month-old toddlers, a single dose of Pn-MAPS24v showed an acceptable safety profile, regardless of dose level; AEs were reported at similar frequencies by Pn-MAPS24v and PCV13 recipients. Pn-MAPS24v elicited IgG and OPA responses to all common and most unique serotypes. These results support further clinical evaluation in infants.

Trends in Otitis Media Ambulatory Visits in American Indian and Alaska Native Children During the Pneumococcal Conjugate Vaccine Period and the COVID-19 Pandemic

Otitis media-associated outpatient visits among American Indians/Alaska Natives children <5 years old decreased by 52% (100 to 48 per 100 children per year) from 2003 to 2019. Otitis media visits decreased by another 50% from 2019 to 2020, but rebounded between 2020 and 2021 back to a rate similar to 2019.

Efficacy of typhoid vaccines against culture-confirmed Salmonella Typhi in typhoid endemic countries: a systematic review and meta-analysis

BACKGROUND

Typhoid is a serious public health threat in many low-income and middle-income countries. Several vaccines for typhoid have been recommended by WHO for typhoid prevention in endemic countries. This study aimed to review the efficacy of typhoid vaccines against culture-confirmed Salmonella enterica serovar Typhi.

METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase for studies published in English between Jan 1, 1986 and Nov 2, 2023. We included randomised controlled trials (RCTs) comparing typhoid vaccines with a placebo or another vaccine. This meta-analysis evaluated the efficacy and safety of several typhoid vaccines, including live attenuated oral Ty21a vaccine, Vi capsular polysaccharide (Vi-PS), Vi polysaccharide conjugated to recombinant Pseudomonas aeruginosa exotoxin A vaccine (Vi-rEPA), and Vi-tetanus toxoid conjugate vaccine (TCV). The certainty of evidence for key outcomes was evaluated using Grading of Recommendations, Assessment, Development, and Evaluations methodology. The outcome of interest was typhoid fever confirmed by the isolation of Salmonella enterica serovar Typhi in blood and adverse events following immunisation. This study is registered with PROSPERO (CRD42021241043).

FINDINGS

We included 14 RCTs assessing four different vaccines (Ty21a: four trials; Vi-PS: five trials; Vi-rEPA: one trial; TCV: four trials) involving 585 253 participants. All trials were conducted in typhoid endemic countries and the age of participants ranged from 6 months to 50 years. The pooled efficacy against typhoid fever was 45% (95% CI 33-55%; four trials; 247 649 participants; I2 59%; moderate certainty) for Ty21a and 58% (44-69%; five trials; 214 456 participants; I2 34%; moderate certainty) for polysaccharide Vi-PS. The cumulative efficacy of two doses of Vi-rEPA vaccine at 2 years was 91% (88-96%; one trial; 12 008 participants; moderate certainty). The pooled efficacy of a single shot of TCV at 2 years post-immunisation was 83% (77-87%; four trials; 111 130 participants; I2 0%; moderate certainty). All vaccines were safe, with no serious adverse effects reported in the trials.

INTERPRETATION

The existing data from included trials provide promising results regarding the efficacy and safety of the four recommended typhoid vaccines. TCV and Vi-rEPA were found to have the highest efficacy at 2 years post-immunisation. However, follow-up data for Vi-rEPA are scarce and only TCV is pre-qualified by WHO. Therefore, roll-out of TCV into routine immunisation programmes in typhoid endemic settings is highly recommended.

FUNDING

There was no funding source for this study.

The pneumococcal conjugate vaccine had a sustained effect on Swedish children 8 years after its introduction

AIM

The pneumococcal conjugate vaccine, which covered seven serotypes of Streptococcus pneumoniae (PCV7), was introduced in Stockholm, Sweden, in 2007. It was replaced by a 13-valent vaccine (PCV13) in 2011. We previously reported a decreased incidence of pneumonia and sinusitis among young children 4 years after the introduction of the PCV7. This study followed the incidence of pneumonia, sinusitis, mastoiditis and meningitis for four more years.

METHODS

We studied validated hospital registry data covering children up to 17 years of age, who were hospitalised in the Stockholm region from 2003 to 2016, when the child population peaked at 485 687. All 11 115 cases diagnosed with pneumonia, coded as bacterial pneumonia, sinusitis, mastoiditis, bacterial meningitis or empyema, were identified. The controls had viral pneumonia or pyelonephritis.

RESULTS

The incidence rates for children under 2 years of age hospitalised for sinusitis, mastoiditis and meningitis decreased significantly by 61%-79% during the eight-year post-vaccination period. Hospitalisations for bacterial pneumonia decreased by 19%-25% in the same age group. These changes were probably due to both the vaccines and changes in diagnosis routines.

CONCLUSION

The effect of vaccination on children under 2 years of age was sustained 8 years after the introduction of the pneumococcal conjugate vaccines.

Necrotizing pneumonia in children: Report of 25 cases between 2008 and 2018 at a French tertiary care center

BACKGROUND

Necrotizing pneumonia (NP) is a serious and rare disease in children. Pediatric data on NP are limited and the impact of the 13-valent pneumococcal conjugate vaccine has been very poorly evaluated.

PATIENTS AND METHODS

We conducted a retrospective study at Toulouse University Hospital between 2008 and 2018. Children who presented with thin-walled cavities in the areas of parenchymal consolidation on imaging were included in the study.

RESULTS

The incidence of NP did not decrease during this period. Bacterial identification occurred in 56% of cases (14/25) and included six cases of Streptococcus pneumoniae, five of Staphylococcus aureus, two of Streptococcus pyogenes, and one of Streptococcus viridans. Streptococcus pneumoniae NP are more frequently associated with empyema/parapneumonic effusion compared to S. aureus NP (p = 0.02). Patients with S. pyogenes NP more often required volume expansion than did S. pneumoniae cases (p = 0.03). When comparing children born before and after implementation of the 13-valent pneumococcal conjugate vaccine, we identified a relative modification of the bacterial epidemiology, with an increase in the proportion of S. pyogenes NP and S. aureus NP and a decrease in the proportion of NP caused by S. pneumoniae.

CONCLUSION

Future studies are needed to assess the epidemiology of NP in children. Continued surveillance of identified pneumococcal serotypes is essential to document epidemiological changes in the coming years.

A phase 3 randomized study to evaluate safety and immunogenicity of 20-valent pneumococcal conjugate vaccine in healthy Japanese infants

OBJECTIVES

Safety and immunogenicity evaluation of a 4-dose series with 20-valent pneumococcal conjugate vaccine (PCV20).

METHODS

This phase 3, double-blind study randomized healthy Japanese infants to receive 4 doses (3 infant doses, 1 toddler dose) of PCV20 by subcutaneous (SC) or intramuscular (IM) injection or 13-valent PCV (PCV13) SC. A primary immunogenicity objective was to demonstrate noninferiority of PCV20 SC to PCV13 SC for percentages of participants meeting predefined serotype-specific immunoglobulin G concentrations 1 month after Dose 3. The 7 additional PCV20 serotypes were compared with the lowest vaccine serotype result in the PCV13 group. Safety and tolerability were assessed as the primary safety objective.

RESULTS

Overall, 668 participants were randomized (PCV20 SC, n = 226; PCV13 SC, n = 224; PCV20 IM, n = 218). The primary noninferiority objective for PCV20 SC to PCV13 SC was met for 11/13 matched and 5/7 additional serotypes. Additional data showed PCV20 SC and IM elicited robust functional opsonophagocytic activity and boosting responses to all 20 vaccine serotypes. PCV20 had a similar safety/tolerability profile to PCV13, although local reactions were less frequent with PCV20 IM.

CONCLUSIONS

A 4-dose series of PCV20 SC or IM elicited immune responses expected to be protective against all 20 serotypes in Japanese infants. NCT04530838.

Pneumococcal conjugate vaccination schedules in infants-acquisition, immunogenicity, and pneumococcal conjugate and yellow fever vaccine co-administration study: statistical analysis plan

RATIONALE

The effectiveness of immunisation with pneumococcal conjugate vaccine (PCV) has been demonstrated in many countries. However, the global impact of PCV is limited by its cost, which has prevented its introduction in some countries. Reducing the cost of PCV programmes will facilitate further vaccine introductions and improve the sustainability of PCV in low-income countries when they transition from subsidised vaccine supply. We are conducting a large, population-level, cluster-randomised field trial (PVS) of an alternative reduced-dose schedule of PCV compared to the standard schedule. We are also conducting a nested sub-study at the individual level to investigate the immunogenicity of the two schedules and their effects on pneumococcal carriage acquisition (PVS-AcqImm).

METHODS AND DESIGN

PVS-AcqImm is a prospective, cluster-randomised trial of an alternative schedule of one dose of PCV scheduled at age 6 weeks with a booster dose at age 9 months compared to the standard of three primary doses scheduled at 6, 10, and 14 weeks of age. Sub-groups within the alternative schedule group receive yellow fever vaccine separately or co-administered with PCV at 9 months of age. The primary endpoints are (a) concentrations of vaccine-type anti-pneumococcal IgG at 18 months of age, (b) proportions with yellow fever neutralising antibody titre ≥ 1:8 4 weeks after separate or co-administration of PCV and yellow fever vaccines, and (c) rate of nasopharyngeal vaccine-type pneumococcal acquisition from 10-14 months of age. Participants and field staff are not masked to group allocation while measurement of the laboratory endpoints is masked. Approximately equal numbers of participants are resident in each of 28 randomly allocated geographic clusters (14 clusters in each group); 784 enrolled for acquisition measurements and 336 for immunogenicity measurements.

PURPOSE

This statistical analysis plan (SAP) describes the PVS-AcqImm cohort and follow-up criteria to be used in different analyses. The SAP defines the endpoints and describes how adherence to the interventions will be presented. We describe the approach to analyses and how we will account for the effect of clustering. Defining the SAP prior to the conduct of analysis will avoid bias in analyses that may arise from prior knowledge of trial findings.

TRIAL REGISTRATION

ISRCTN, ISRCTN7282161328. Registered on 28 November 2019. https://www.isrctn.com/ISRCTN72821613 .

PROTOCOL

MRCG SCC number 1670, LSHTM Ref 17683. Current protocol version: 6.0, 24 May 2021. Version: 1.0 (5 April 2023); SAP revisions-none.

Immune responses to typhoid conjugate vaccine in a two dose schedule among Nepalese children <2 years of age

BACKGROUND

Previously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of Vi-TT at 9 and 12 months of age and response to a booster dose at 15 months of age.

METHODS

Infants were recruited at Patan Hospital, Kathmandu and received an initial dose of Vi-TT at 9 or 12 months of age with a booster dose at 15 months of age. Blood was taken at four timepoints, and antibody titres were measured using a commercial ELISA kit. The primary study outcome was seroconversion (4-fold rise in antibody titre) of IgG one month after both the doses.

FINDINGS

Fifty children were recruited to each study group.Some visits were disrupted by the COVID19 pandemic and occurred out of protocol windows.Both the study groups attained 100 % IgG seroconversion after the initial dose. IgG seroconversion in the 9-month group was significantly higher than in the 12-month group (68.42 % vs 25.8 %, p < 0.001). Among individuals who attended visits per protocol, IgG seroconversion after the first dose occurred in 100 % of individuals (n = 27/27 in 9-month and n = 32/32 in 12-month group). However, seroconversion rates after the second dose were 80 % in the 9-month and 0 % in the shorter dose-interval 12-month group (p < 0.001) (n = 16/20 and n = 0/8, respectively).

INTERPRETATION

Vi-TT is highly immunogenic at both 9 and 12 months of age. Stronger response to a booster in the 9-month group is likely due to the longer interval between doses.

A conjugate vaccine strategy that induces protective immunity against arecoline

Betel-quid chewing addiction is the leading cause of oral submucous fibrosis and oral cancer, resulting in significant socio-economic burdens. Vaccination may serve as a promising potential remedy to mitigate the abuse and combat accidental overdose of betel nut. Hapten design is the crucial factor to the development of arecoline vaccine that determines the efficacy of a candidate vaccine. Herein, we reported that two kinds of novel arecoline-based haptens were synthesized and conjugated to Bovine Serum Albumin (BSA) to generate immunogens, which generated antibodies with high affinity for arecoline but reduced binding for guvacoline and no affinity for arecaidine or guvacine. Notably, vaccination with Arec-N-BSA, which via the N-position on the tetrahydropyridine ring (tertiary amine group), led to a higher antibody affinity compared to Arec-CONH-BSA, blunted analgesia and attenuated hypothermia for arecoline.

Surveillance of pneumococcal serotypes in adults hospitalised with acute lower respiratory tract infection in Bristol, UK

INTRODUCTION

Pneumococcus remains a major cause of adult lower respiratory tract infections (LRTI). Few data exist on the relative contribution of serotypes included in pneumococcal vaccines to community-acquired pneumonia (CAP) and non-pneumonic (NP) LRTI. We measured the burden of all and vaccine-serotype pneumococcal respiratory infection following SARS-CoV-2 emergence to inform evidence-based vaccination policy.

METHODS

A prospective cohort study at two Bristol hospitals (UK) including all adults age ≥ 18-years hospitalised with acute lower respiratory tract disease (aLRTD) from Nov2021-Nov2022. LRTI patients were classified as: a) radiographically-confirmed CAP (CAP+/RAD+), b) clinically-diagnosed CAP without radiological confirmation (CAP+/RAD-), or c) NP-LRTI. Pneumococcus was identified by blood culture, BinaxNOW™and serotype-specific urine antigen detection assays (UAD).

RESULTS

Of 12,083 aLRTD admissions, 10,026 had LRTI and 2,445 provided urine: 1,097 CAP + RAD+; 207 CAP + RAD-; and 1,141 NP-LRTI. Median age was 71.1y (IQR57.9-80.2) and Charlson comorbidity index = 4 (IQR2-5); 2.7 % of patients required intensive care, and 4.4 % died within 30-days of hospitalisation. Pneumococcus was detected in 280/2445 (11.5 %) participants. Among adults aged ≥ 65y and 18-64y, 12.9 % (198/1534) and 9.0 % (82/911), respectively, tested pneumococcus positive. We identified pneumococcus in 165/1097 (15.0 %) CAP + RAD+, 23/207 (11.1 %) CAP + RAD-, and 92/1141 (8.1 %) NP-LRTI cases. Of the 280 pneumococcal cases, 102 (36.4 %) were due to serotypes included in PCV13 + 6C, 115 (41.7 %) in PCV15 + 6C, 210 (75.0 %) in PCV20 + 6C/15C and 228 (81.4 %) in PPV23 + 15C. The most frequently identified serotypes were 8 (n = 78; 27.9 % of all pneumococcus), 7F (n = 25; 8.9 %), and 3 (n = 24; 8.6 %).

DISCUSSION

Among adults hospitalised with respiratory infection, pneumococcus is an important pathogen across all subgroups, including CAP+/RAD- and NP-LRTI. Despite 20-years of PPV23 use in adults ≥ 65-years and herd protection due to 17-years of PCV use in infants, vaccine-serotype pneumococcal disease still causes a significant proportion of LRTI adult hospitalizations. Direct adult vaccination with high-valency PCVs may reduce pneumococcal disease burden.

Immunization with a whole cell vaccine reduces pneumococcal nasopharyngeal density and shedding, and middle ear infection in mice

Pneumococcal Conjugate Vaccines (PCVs) have substantially reduced the burden of disease caused by Streptococcus pneumoniae (the pneumococcus). However, protection is limited to vaccine serotypes, and when administered to children who are colonized with pneumococci at the time of vaccination, immune responses to the vaccine are blunted. Here, we investigate the potential of a killed whole cell pneumococcal vaccine (WCV) to reduce existing pneumococcal carriage and mucosal disease when given therapeutically to infant mice colonized with pneumococci. We show that a single dose of WCV reduced pneumococcal carriage density in an antibody-dependent manner. Therapeutic vaccination induced robust immune responses to pneumococcal surface antigens CbpA, PspA (family 1) and PiaA. In a co-infection model of otitis media, a single dose of WCV reduced pneumococcal middle ear infection. Lastly, in a two-dose model, therapeutic administration of WCV reduced nasal shedding of pneumococci. Taken together, our data demonstrate that WCV administered in colonized mice reduced pneumococcal density in the nasopharynx and the middle ear, and decreased shedding. WCVs would be beneficial in low and middle-income settings where pneumococcal carriage in children is high.

Propositive follow-up: Long-term immune responses to the 4CMenB and MenACWY vaccines in people living with HIV

BACKGROUND

People living with HIV have an increased risk of meningococcal disease. The Propositive trial evaluated co-administration of two doses of a four-component recombinant protein-based MenB vaccine (4CMenB) and a quadrivalent conjugate polysaccharide MenACWY vaccine (MenACWY-CRM197) given 1 month apart in people with HIV. The follow-up trial assessed the immunogenicity of these vaccines at 1.5 and 2.5 years after primary vaccination.

METHODS

Participants who completed the parent Propositive trial were invited to the follow-up study. Immunogenicity analysis was performed at 18 and 30 months after primary vaccination. Primary outcome measures were serum bactericidal antibody (SBA) geometric mean titres (GMTs) against three MenB reference strains and the proportion of participants maintaining a protective SBA titre of ≥4 at 18 and 30 months. Secondary outcome measures were SBA GMTs against MenA, C, W, and Y serogroups and the proportion of participants maintaining a protective SBA titre of ≥8 at 18 and 30 months. The trial is registered with Clinicaltrials.gov (NCT042394300).

RESULTS

A total of 40 participants aged 22-47 years were enrolled. Geometric mean titres waned by 18 and 30 months but remained higher than pre-vaccination for all MenB strains and MenA, C, W, and Y. In total, 75%-85% of participants retained protective SBA titres by 30 months against individual MenB strains, whereas 68.8% of patients retained protective antibody titres against all three MenB strains. Antibodies against MenC waned more rapidly than did those against MenA, W, and Y. The proportion of participants with protective titres against MenC at 30 months was also lower (46.9%) than that with protective titres against MenA (87.5%), W (78.1%), and Y (87.5%).

CONCLUSIONS

Immune responses against MenB in our cohort of people living with HIV at 2.5 years of follow-up were reassuring, with 68.8% of participants retaining protection against all three reference strains. However, responses against MenC were lower than those against MenA, W, and Y serogroups.

Assessing prescription of antibiotics after vaccination against pneumococcal pneumonia; using prescription sequence symmetry analysis

OBJECTIVES

Prescription sequence symmetry analysis (PSSA) is used to detect adverse event signals using administrative claims databases. In this study, we investigated whether PSSA can be applied to gauge the effects of PCV13 vaccination on antibiotic prescription rates in elderly patients.

METHODS

We studied prescription records of patients aged 65 or older between 1 January 2014 and 31 December 2020, from the Helsana Swiss claims database. PSSA was performed to explore the relationship between 13-valent pneumococcal conjugate vaccine (PCV13) and six antibiotics recommended by the Swiss Society of Infectious Diseases for community-acquired pneumonia treatment (amoxicillin-clavulanate, azithromycin, clarithromycin, doxycycline, levofloxacin, and moxifloxacin), three additional antibiotics (amoxicillin, ciprofloxacin, and fosfomycin), and ten control drugs.

RESULTS

Amoxicillin-clavulanate, clarithromycin, and levofloxacin were more likely to be prescribed before than after vaccination, for all time windows between 25 and 104 weeks. Adjusted sequence ratio (ASR) values ranged from 0.599 to 0.614, 0.508 to 0.568, and 0.514 to 0.752, respectively. Lower prescription rates after vaccination were also observed for azithromycin (all time windows between 38 and 104 weeks, ASR 0.705-0.739) and moxifloxacin (all time windows between 52 and 104 weeks, ASR 0.658-0.772). PCV13 did not have statistically significant associations with doxycycline, amoxicillin, ciprofloxacin, fosfomycin, or any of the ten controls.

DISCUSSION

The lower prescription rate of antibiotics for community-acquired pneumonia after vaccination could be attributed to a protective effect of PCV13. This novel application of PSSA can be used to compare the real-world impact of other vaccines on drug consumption.

Panel 1: Epidemiology and global health, including child development, sequelae and complications

OBJECTIVE

To summarise the published research evidence on the epidemiology of otitis media, including the risk factors and sequelae associated with this condition.

DATA SOURCES

Medline (PubMed), Embase, and the Cochrane Library covering the period from 2019 to June 1st, 2023.

REVIEW METHODS

We conducted a broad search strategy using otitis [Medical Subject Heading] combined with text words to identify relevant articles on the prevalence, incidence, risk factors, complications, and sequelae for acute otitis media, otitis media with effusion, and chronic suppurative otitis media. At least one review author independently screened titles and abstracts of the retrieved records for each condition to determine whether the research study was eligible for inclusion. Any discrepancies were resolved by reviewing the full text followed by discussion with a second review author. Studies with more than 100 participants were prioritised.

RESULTS

Over 2,000 papers on otitis media (OM) have been published since 2019. Our review has highlighted around 100 of these publications. While the amount of otitis media research on the Medline database published each year has not increased, there has been an increase in epidemiological studies using routinely collected data and systematic review methodology. Most of the large incidence studies have addressed acute otitis media (AOM) in children. Several studies have described a decrease in incidence of AOM after the introduction of conjugate PCV vaccines. Similarly, a decrease was noted when rates of coronavirus disease of 2019 (COVID-19) were high and there were major public health efforts to reduce the spread of infection. There have been new studies on OM in adults and OM prevalence in a broader range of countries and population subgroups.

CONCLUSION

Overall, the rates of severe and/or suppurative OM appeared to be decreasing. However, there is substantial heterogeneity between populations. While better use of available data is informative, it can be difficult to predict rates of severe disease without accurate examination findings. Most memorably, the COVID-19 pandemic had an enormous impact on the research and clinical services for otitis media for most of the period under review.

IMPLICATIONS FOR PRACTICE

The use of routinely collected data for epidemiological studies will lead to greater variability in the definitions and diagnostic criteria used. The impact of new vaccines will continue to be important. Some of the lessons learned during the COVID-19 pandemic concerning behaviours that reduce spread of respiratory viruses can hopefully be used to decrease the burden of otitis media in the future. There are still many countries in the world where the burden of otitis media is not well described. In countries where otitis media has been studied over many years, new potential risk factors continue to be identified. In addition, a better understanding of the disease in specific subgroups has been achieved.

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

BACKGROUND

Despite substantial reductions in pneumococcal disease with the availability of pneumococcal conjugate vaccines, a significant burden of pneumococcal disease remains due to the diversity of serotypes combined with serotype replacement. We developed a new vaccine candidate, VAX-24 (24-valent pneumococcal conjugate vaccine), using cell-free protein synthesis to produce a variant of cross-reactive material 197 (eCRM) as the carrier protein, increasing serotype coverage while minimising carrier suppression. The aim of this clinical trial was to assess the safety, tolerability, and immunogenicity of three different doses of VAX-24 compared to pneumococcal 20-valent conjugate vaccine (PCV20).

METHODS

This was a phase 1/2, randomised, double-masked study of VAX-24 versus PCV20 conducted in the USA. Key inclusion criteria included being a male or female aged 18 to 64 years in good health; key exclusion criteria included previous history of pneumococcal disease, receipt of a licensed or investigational pneumococcal vaccine, or immunosuppressive therapy. Participants were randomly allocated in a 1:1:1:1 ratio by permuted block to receive one dose of VAX-24 (1·1 μg of each antigen, 2·2 μg of each antigen, or 2·2 μg of 17 antigens mixed with 4·4 μg of seven antigens), or PCV20. The safety population included all participants with safety data. The immunogenicity population was as per-treatment in phase 2. Primary outcome measures included solicited and unsolicited adverse events. Secondary outcomes included serotype-specific opsonophagocytic activity (OPA) geometric mean titres (GMT), and IgG geometric mean concentrations (GMC) were measured 1 month postvaccination. Traditional non-inferiority criteria included OPA geometric mean ratio (GMR), with a lower bound of the two sided 95% CI of greater than 0·5 for shared serotypes. This completed trial is registered at ClinicalTrials.gov, NCT05266456.

FINDINGS

Safety profiles were comparable among the treatment groups, with 170 of 209 participants (81%, 95% CI 75·2-86·2) to 178 of 207 participants (86%, 80·5-90·4) reporting at least one solicited adverse event among the three VAX-24 groups. 24 of 207 participants (12%, 7·6-16·8) to 32 of 209 of participants (15%, 10·7-20·9) experiened an unsolicited treatment emergent adverse event within 1 month postvaccination. VAX-24 2·2 μg met traditional OPA GMR non-inferiority criteria for all 20 shared serotypes; 16 serotypes elicited GMR point estimates greater than 1·0, and four reached the lower bound of the two-sided 95% CI greater than 1·0.

INTERPRETATION

VAX-24 had a safety profile similar to PCV20 at all doses, with the 2·2 μg dose showing increased serotype coverage with decreased carrier suppression.

FUNDING

Vaxcyte.

Serotype 3 Antibody Response and Antibody Functionality Compared to Serotype 19A Following 13-Valent Pneumococcal Conjugate Immunization in Children

BACKGROUND

Prevention of infections in children vaccinated with 13-valent pneumococcal conjugate vaccine (PCV13) may be less effective against serotype 3 than 19A.

OBJECTIVE

The aim of this study was to to determine differences in IgG and functional antibody for serotype 3 versus 19A following PCV13 immunization, in IgG antibody levels induced by PCV13 compared to naturally-induced immunity, and assess effectiveness of PCV13 against serotype 3 and 19A in prevention of acute otitis media (AOM) and colonization among 6-36-month-old children.

METHODS

Samples were from a prospective, longitudinal, observational cohort study conducted in Rochester, NY. Pneumococcal detection was by culture. 713 serum were tested for antibody levels by enzyme-linked immunosorbent assay, 68 for functional antibody by opsonophagocytosis and 47 for antibody avidity by thiocyanate bond disruption. PCV13 effectiveness in preventing AOM and colonization was determined by comparison of pre-PCV13 detection of serotypes 3 and 19A to post-PCV13.

RESULTS

The proportion of children who reached the antibody threshold of ≧0.35 µg/mL after PCV13 was higher for serotype 19A than serotype 3. Only serotype 19A showed significant increase in PCV13-induced opsonophagocytosis assay titers and antibody avidity. Serotype 3 naturally-induced immune children showed a positive trend of increase in antibody level as children got older, but not PCV13-immunized children. PCV13 effectiveness was not identified in preventing AOM or colonization for serotype 3 but effectiveness of 19A was confirmed.

CONCLUSIONS

PCV13 elicits lower antibody levels and lower effectiveness to serotype 3 versus serotype 19A. Post-PCV13-induced antibody levels for serotype 3 are likely insufficient to prevent AOM and colonization in most young children.

Effect of Pneumococcal Conjugate Vaccine on Pneumonia Incidence Rates among Children 2-59 Months of Age, Mongolia, 2015-2021

Starting in June 2016, the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced into the routine immunization program of Mongolia by using a 2+1 dosing schedule, phased by district. We used prospective hospital surveillance to evaluate the vaccine's effect on pneumonia incidence rates among children 2-59 months of age over a 6-year period. Of 17,607 children with pneumonia, overall adjusted incidence rate ratios showed decreased primary endpoint pneumonia, very severe pneumonia, and probable pneumococcal pneumonia until June 2021. Results excluding and including the COVID-19 pandemic period were similar. Pneumonia declined in 3 districts that introduced PCV13 with catch-up campaigns but not in the 1 district that did not. After PCV13 introduction, vaccine-type pneumococcal carriage prevalence decreased by 44% and nonvaccine-type carriage increased by 49%. After PCV13 introduction in Mongolia, the incidence of more specific pneumonia endpoints declined in children 2-59 months of age; additional benefits were conferred by catch-up campaigns.

Streptococcus pneumoniae serotype 3 population structure in the era of conjugate vaccines, 2001-2018

Background. Despite use of highly effective conjugate vaccines, invasive pneumococcal disease (IPD) remains a leading cause of morbidity and mortality and disproportionately affects Indigenous populations. Although included in the 13-valent pneumococcal conjugate vaccine (PCV13), which was introduced in 2010, serotype 3 continues to cause disease among Indigenous communities in the Southwest USA. In the Navajo Nation, serotype 3 IPD incidence increased among adults (3.8/100 000 in 2001-2009 and 6.2/100 000 in 2011-2019); in children the disease persisted although the rates dropped from 5.8/100 000 to 2.3/100 000.Methods. We analysed the genomic epidemiology of serotype 3 isolates collected from 129 adults and 63 children with pneumococcal carriage (n=61) or IPD (n=131) from 2001 to 2018 of the Navajo Nation. Using whole-genome sequencing data, we determined clade membership and assessed changes in serotype 3 population structure over time.Results. The serotype 3 population structure was characterized by three dominant subpopulations: clade II (n=90, 46.9 %) and clade Iα (n=59, 30.7 %), which fall into Clonal Complex (CC) 180, and a non-CC180 clade (n=43, 22.4 %). The proportion of clade II-associated IPD cases increased significantly from 2001 to 2010 to 2011-2018 among adults (23.1-71.8 %; P<0.001) but not in children (27.3-33.3 %; P=0.84). Over the same period, the proportion of clade II-associated carriage increased; this was statistically significant among children (23.3-52.6 %; P=0.04) but not adults (0-50.0 %, P=0.08).Conclusions. In this setting with persistent serotype 3 IPD and carriage, clade II has increased since 2010. Genomic changes may be contributing to the observed trends in serotype 3 carriage and disease over time.

Effectiveness of 13-valent pneumococcal conjugate vaccine against vaccine-serotype community acquired pneumococcal diseases among children in China: A test-negative case-control study

BACKGROUND

In 2016, China licensed 13-valent pneumococcal conjugate vaccine (PCV13) based on a study that demonstrated its immunogenicity is non-inferior to PCV7. However, the real-world effectiveness of PCV13 against vaccine-serotype pneumococcal diseases in China has limited evidence.

METHODS

A test-negative case-control study was conducted among children under 5 years old admitted to the Children's Hospital of Soochow University (SCH) with respiratory tract infections from January 2018 to December 2020. Cases were defined as children from whom the isolates were tested positive for Streptococcus pneumoniae (S. pneumoniae) with serotypes included in PCV13. Two control groups were included, one represented children with isolates positive for S. pneumoniae of non-PCV13 serotypes and the other comprised children who tested negative for S. pneumoniae. The S. pneumoniae-negative controls were selected by matching them to the cases based on gender, age and admission date in a 1:1 ratio. Vaccine effectiveness (VE) was calculated using a logistic regression model as (1- adjusted odds ratio) * 100 %.

RESULTS

A total of 2371 pneumococcal isolates were included in the analysis, of which 75.0 % (1779/2371) were covered by PCV13 serotypes. Consequently, these 1779 children were classified as cases, and 592 children were designated as non-PCV13 serotype controls. Another 1779 children were correspondingly recruited as S. pneumoniae-negative controls. Overall, 40 cases (2.3 %) and 148 controls (6.2 %) had received vaccination. The overall VE in the PCV13/non-PCV13 serotypes case-control study was 50.0 % (95 % CI: 15.0, 70.7), which was lower than the VE of 74.4 % (95 % CI: 60.7, 83.3) in the matched PCV13/S. pneumoniae-negative case-control study. VE was higher for ≥ 2 or ≥ 3 doses of vaccination compared to ≥ 1 dose. VE against specific PCV13 serotypes (6B, 6A and 19F) was higher than for other serotypes.

CONCLUSIONS

PCV13 vaccination demonstrates effectiveness against vaccine-serotype pneumococcal diseases in children, particularly for serotypes 6B, 6A and 19F.

A review of potential use cases for measles-rubella, measles-mumps-rubella, and typhoid-conjugate vaccines presented on microarray patches

As an innovative vaccine delivery technology, vaccine microarray patches could have a meaningful impact on routine immunization coverage in low- and middle-income countries, and vaccine deployment during epidemics and pandemics. This review of the potential use cases for a subset of vaccine microarray patches in various stages of clinical development, including measles-rubella, measles-mumps-rubella, and typhoid conjugate, highlights the breadth of their applicability to support immunization service delivery and their potential scope of utilization within national immunization programs. Definition and assessment of the use cases for this novel vaccine presentation provide important insights for vaccine developers and policymakers into the strengths of the public health and commercial value propositions, and the preparatory requirements for public health systems for the future rollout of vaccine microarray patches. An in-depth understanding of use cases for vaccine microarray patches serves as a foundational input to overcoming the remaining technical, regulatory, and financial challenges. Additional efforts will help to realize the potential of vaccine microarray patches as part of the global effort to improve the coverage and equity of national immunization programs.

Higher-valency pneumococcal conjugate vaccines in older adults, taking into account indirect effects from childhood vaccination: a cost-effectiveness study for the Netherlands

BACKGROUND

New 15- and 20-valent pneumococcal vaccines (PCV15, PCV20) are available for both children and adults, while PCV21 for adults is in development. However, their cost-effectiveness for older adults, taking into account indirect protection and serotype replacement from a switch to PCV15 and PCV20 in childhood vaccination, remains unexamined.

METHODS

We used a static model for the Netherlands to assess the cost-effectiveness of different strategies with 23-valent pneumococcal polysaccharide vaccine (PPV23), PCV15, PCV20, and PCV21 for a 65-year-old cohort from a societal perspective, over a 15-year time horizon. Childhood vaccination was varied from PCV10 to PCV13, PCV15, and PCV20. Indirect protection was assumed to reduce the incidence of vaccine serotypes in older adults by 80% (except for serotype 3, no effect), completely offset by an increase in non-vaccine serotype incidence due to serotype replacement.

RESULTS

Indirect effects from childhood vaccination reduced the cost-effectiveness of vaccination of older adults, depending on the serotype overlap between the vaccines. With PCV10, PCV13, or PCV15 in children, PCV20 was more effective and less costly for older adults than PPV23 and PCV15. PCV20 costs approximately €10,000 per quality-adjusted life year (QALY) gained compared to no pneumococcal vaccination, which falls below the conventional Dutch €20,000/QALY gained threshold. However, with PCV20 in children, PCV20 was no longer considered cost-effective for older adults, costing €22,550/QALY gained. As indirect effects progressed over time, the cost-effectiveness of PCV20 for older adults further diminished for newly vaccinated cohorts. PPV23 was more cost-effective than PCV20 for cohorts vaccinated 3 years after the switch to PCV20 in children. PCV21 offered the most QALY gains, and its cost-effectiveness was minimally affected by indirect effects due to its coverage of 11 different serotypes compared to PCV20.

CONCLUSIONS

For long-term cost-effectiveness in the Netherlands, the pneumococcal vaccine for older adults should either include invasive serotypes not covered by childhood vaccination or become more affordable than its current pricing for individual use.