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- Title
Four-Component Recombinant Protein–Based Vaccine Effectiveness Against Serogroup B Meningococcal Disease in Italy.
- Authors
Lodi, Lorenzo; Barbati, Federica; Amicizia, Daniela; Baldo, Vincenzo; Barbui, Anna Maria; Bondi, Alessandro; Costantino, Claudio; Da Dalt, Liviana; Ferrara, Lorenza; Fortunato, Francesca; Guarnieri, Valentina; Icardi, Giancarlo; Indolfi, Giuseppe; Martinelli, Domenico; Martini, Marco; Moriondo, Maria; Nieddu, Francesco; Peroni, Diego G.; Prato, Rosa; Ricci, Silvia
- Abstract
Key Points: Question: What is the effectiveness associated with the 4-component recombinant protein–based (4CMenB) vaccine in preventing serogroup B meningococcal disease in pediatric populations younger than 6 years in Italy? Findings: This cohort screening study (3 regions; resident population: 587 561 children) and matched case-control study (6 regions; resident population: 1 080 620 children) of children younger than 6 years found that 4CMenB was associated with an effectiveness of more than 90% in children old enough to receive the first vaccine dose. Early-start vaccination programs were associated with reduced incidence rate ratios, and almost 20% of cases among unvaccinated children were among children too young to receive the first 4CMenB dose. Meaning: These findings suggest that new vaccination strategies should target children currently too young to be vaccinated. This case-control study assess the effectiveness associated with the 4-component recombinant protein–based vaccine against meningococcal disease among children aged 6 years and younger in Italy. Importance: Population-based data on the 4-component recombinant protein–based (4CMenB) vaccine effectiveness and reduction in incidence rate ratios (IRRs) are continuously needed to assess vaccine performance in the prevention of serogroup B invasive meningococcal disease (IMD). Objective: To assess the effectiveness and reduction in IRRs associated with the 4CMenB vaccine in the pediatric population in 6 regions in Italy. Design, Setting, and Participants: This retrospective cohort screening study and case-control study included data from children aged younger than 6 years in 6 highly populated Italian regions from January 1, 2006, to January 1, 2020. Participants included children younger than 6 years diagnosed with serogroup B IMD without predisposing factors. Data were collected from regional surveillance and vaccination registries and were analyzed from September 2021 to January 2022. Exposures: Routine 4CMenB vaccination, per regional vaccination programs. Main Outcomes and Measures: The main outcome was the effectiveness of the 4CMenB vaccine in the prevention of serogroup B IMD in the population of children aged younger than 6 years in 6 Italian regions. The percentages of vaccine effectiveness (VE) were obtained through the concomitant use of a screening method and a case-control study. Secondary outcomes were the comparison of effectiveness results obtained using the 2 different computational methods, the description of serogroup B IMD incidence rates, and reduction in IRRs before and after 4CMenB introduction, as a proxy for vaccine impact. Results: The cohort screening study included a resident population of 587 561 children younger than 6 years in 3 regions with similar surveillance protocols, and the matched-case controls study assessed a resident population of 1 080 620 children younger than 6 years in 6 regions. Analyses found that 4CMenB VE in fully immunized children was 94.9% (95% CI, 83.1%-98.4%) using the screening method and 91.7% (95% CI, 24.4%-98.6%) using the case-control method. Overall reduction in IRR was 50%, reaching 70% in regions with early-start vaccination schedules. The case-control method involving 6 highly-populated Italian regions included 26 cases and 52 controls and found an estimated VE of 92.4% (95% CI, 67.6%-97.9%) in children old enough for the first vaccine dose and 95.6% (95% CI, 71.7%-99.1%) in fully immunized children. VE was more than 90% for partially immunized children. Even in regions where the first dose was administered at age 2 months, almost 20% of unvaccinated cases were among infants too young to receive the first 4CMenB dose. Conclusions and Relevance: This screening cohort study and matched case-controls study found high effectiveness of 4CMenB vaccination and greater reduction in IRR for early-start vaccination schedules in preventing invasive serogroup B meningococcal disease. The high proportion of children too young to be vaccinated among unvaccinated cases suggests that starting the vaccination even earlier may prevent more cases. Screening and case-control methods provided similar estimates of VE: either method may be used in different study settings, but concomitant use can provide more robust estimates.
- Subjects
ITALY; IMMUNIZATION; CONFIDENCE intervals; RETROSPECTIVE studies; CASE-control method; PEDIATRICS; RESPIRATORY measurements; DISEASE incidence; MENINGOCOCCAL vaccines; VACCINE effectiveness; SEROTYPES; MEDICAL protocols; DESCRIPTIVE statistics; RESEARCH funding; NEISSERIA meningitidis; RECOMBINANT proteins; LONGITUDINAL method
- Publication
JAMA Network Open, 2023, Vol 6, Issue 8, pe2329678
- ISSN
2574-3805
- Publication type
Article
- DOI
10.1001/jamanetworkopen.2023.29678