Pneumococcal conjugate vaccination in The Gambia: health impact, cost effectiveness and budget implications

IntroductionIntroducing pneumococcal conjugate vaccine (PCV) in many low-income countries has contributed to reductions in global childhood deaths caused by Streptococcus pneumoniae. Many low-income countries, however, will soon reach an economic status leading to transition from Gavi, the Vaccine Alliance vaccine funding support and then face increased expenditure to continue PCV programmes. Evaluating the cost-effectiveness of PCV in low-income countries will inform such country decisions.MethodsWe used empiric data on the costs of vaccine delivery and pneumococcal disease and PCV programme impact on disease among children less than 5 years old in The Gambia. We used the UNIVAC cost-effectiveness modelling tool to compare the impact and cost-effectiveness of pneumococcal conjugate vaccination to no vaccination over 20 birth cohorts starting in 2011. We calculated costs per disability-adjusted-life-year (DALY) averted from government and societal perspectives and undertook scenario and probabilistic sensitivity analysis.ResultsWe projected that, over 20 years, PCV in The Gambia could avert 117 000 total disease episodes in children less than 5 years old, including outpatient and hospitalised pneumonia, pneumococcal sepsis and meningitis (including sequelae). Vaccination could avert 9000 outpatient pneumonia visits, 88 000 hospitalisations and 3300 deaths due to pneumonia, meningitis and sepsis. Approximately 100 000 DALYs are expected to be averted. Averted visits and hospitalisations represent US$4 million in healthcare costs expected to be saved by the government and US$7.3 million if household costs are included. The cost of the vaccination programme is estimated at US$2 million. In the base scenario, most alternative scenarios and nearly 90% of the probabilistic scenarios, pneumococcal vaccination is cost saving in The Gambia.ConclusionPneumococcal conjugate vaccination is expected to generate substantial health gains and is likely to be cost saving in The Gambia. Policymakers in similar settings should be confident to maintain their PCV programmes.

Vaccine impact and effectiveness of meningococcal serogroup ACWY conjugate vaccine implementation in the Netherlands: a nationwide surveillance study

Background In response to the recent serogroup W invasive meningococcal disease (IMD-W) epidemic in the Netherlands, meningococcal serogroup C (MenC) conjugate vaccination for 14-month-olds was replaced with a MenACWY conjugate vaccination, and a mass campaign targeting 14-18 year-olds was executed. We investigated the impact of MenACWY vaccination implementation in 2018-2020 on incidence rates and estimated vaccine effectiveness (VE). Methods We extracted all IMD cases diagnosed between July 2014 and December 2020 from the national surveillance system. We calculated age group-specific incidence rate ratios by comparing incidence rates before (July 2017-March 2018) and after (July 2019-March 2020) MenACWY vaccination implementation. We estimated VE in vaccine-eligible cases using the screening method. Results Overall, IMD-W incidence rate lowered by 61% (95%CI 40-74). It declined by 82% (95%CI 18-96) in vaccine-eligible age group (15-36 month-olds and 14-18 year-olds) and by 57% (95%CI 34-72) in vaccine non-eligible age groups. VE was 92% (95%CI -20-99.5) against IMD-W vaccine-eligible toddlers. No IMD-W cases were reported in vaccine-eligible teenagers after the campaign. Conclusions The MenACWY vaccination programme was effective in preventing IMD-W in the target population. The IMD-W incidence reduction in vaccine non-eligible age groups may be caused by indirect effects of the vaccination programme. However, disentangling natural fluctuation from vaccine-effect was not possible. Our findings encourage the use of toddler- and teenager MenACWY vaccination in national immunization programmes especially when implemented together with a teenager mass campaign during an epidemic.

Microbiota development in early life mediates association between mode of delivery and vaccine responses

The gut microbiota in early life, when critical immune maturation takes place, may influence the immunogenicity of childhood vaccinations. We assessed the association between mode of delivery, gut microbiota development in the first year of life, and mucosal antigen-specific immunoglobulin G (IgG) responses against pneumococcal and meningococcal conjugate vaccination at ages 12 and 18 months, respectively, in a prospective birth cohort of 120 infants. Birth by natural delivery was associated with higher IgG responses against both vaccines, which for the anti-pneumococcal IgG response could be explained by a gut microbial community composition with high abundances of Bifidobacterium and Escherichia coli in the first weeks of life. High E. coli abundance in the same period was also associated with higher anti-meningococcal IgG responses. Our results suggest that associations between mode of delivery and antibody responses to routine childhood vaccines are mediated by gut microbiota development.