Dataset Information

Comparison of static and dynamic models of maternal immunization to prevent infant pertussis in Brazil.

ABSTRACT:

Background

This paper compares cost-effectiveness results from two models of maternal immunization to prevent pertussis in infants in Brazil, one static, one dynamic, to explore when static models are adequate for public health decisions and when the extra effort required by dynamic models is worthwhile.

Methods

We defined two scenarios to explore key differences between static and dynamic models, herd immunity and time horizon. Scenario 1 evaluates the incremental cost/DALY of maternal acellular pertussis (aP) immunization as routine infant vaccination coverage ranges from low/moderate up to, and above, the threshold at which herd immunity begins to eliminate pertussis. Scenario 2 compares cost-effectiveness estimates over the models' different time horizons. Maternal vaccine prices of $9.55/dose (base case) and $1/dose were evaluated.

Results

The dynamic model shows that maternal immunization could be cost-saving as well as life-saving at low levels of infant vaccination coverage. When infant coverage reaches the threshold range (90-95%), it is expensive: the dynamic model estimates that maternal immunization costs $2 million/DALY at infant coverage > 95% and maternal vaccine price of $9.55/dose; at $1/dose, cost/DALY is $200,000. By contrast, the static model estimates costs/DALY only modestly higher at high than at low infant coverage. When the models' estimates over their different time horizons are compared at infant coverage < 90-95%, their projections fall in the same range.

Conclusions

Static models may serve to explore an intervention's cost-effectiveness against infectious disease: the direction and principal drivers of change were the same in both models. When, however, an intervention too small to have significant herd immunity effects itself, such as maternal aP immunization, takes place against a background of vaccination in the rest of the population, a dynamic model is crucial to accurate estimates of cost-effectiveness. This finding is particularly important in the context of widely varying routine infant vaccination rates globally.

Clinical trial registry

Clinical Trial registry name and registration number: Not applicable.

SUBMITTER: Russell LB

PROVIDER: S-EPMC7735374 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Comparison of static and dynamic models of maternal immunization to prevent infant pertussis in Brazil.

Russell Louise B LB Kim Sun-Young SY Toscano Cristiana C Cosgriff Ben B Minamisava Ruth R Lucia Andrade Ana A Sanderson Colin C Sinha Anushua A

Vaccine 20210101 1

<h4>Background</h4>This paper compares cost-effectiveness results from two models of maternal immunization to prevent pertussis in infants in Brazil, one static, one dynamic, to explore when static models are adequate for public health decisions and when the extra effort required by dynamic models is worthwhile.<h4>Methods</h4>We defined two scenarios to explore key differences between static and dynamic models, herd immunity and time horizon. Scenario 1 evaluates the incremental cost/DALY of ma ...[more]

PMID: 33303183

Similar Datasets

Project description:ObjectiveThis study evaluates the cost-effectiveness of maternal acellular pertussis (aP) immunization in low- and middle-income countries using a dynamic transmission model.MethodsWe developed a dynamic transmission model to simulate the impact of infant vaccination with whole-cell pertussis (wP) vaccine with and without maternal aP immunization. The model was calibrated to Brazilian surveillance data and then used to project health outcomes and costs under alternative strategies in Brazil, and, after adjusting model parameter values to reflect their conditions, in Nigeria and Bangladesh. The primary measure of cost-effectiveness is incremental cost (2014 USD) per disability-adjusted life-year (DALY).ResultsThe dynamic model shows that maternal aP immunization would be cost-effective in Brazil, a middle-income country, under the base-case assumptions, but would be very expensive at infant vaccination coverage in and above the threshold range necessary to eliminate the disease (90-95%). At 2007 infant coverage (DTP1 90%, DTP3 61% at 1 year of age), maternal immunization would cost < $4,000 per DALY averted. At high infant coverage, such as Brazil in 1996 (DTP1 94%, DTP3 74% at 1 year), cost/DALY increases to $1.27 million. When the model's time horizon was extended from 2030 to 2100, cost/DALY increased under both infant coverage levels, but more steeply with high coverage. The results were moderately sensitive to discount rate, maternal vaccine price, and maternal aP coverage and were robust using the 100 best-fitting parameter sets. Scenarios representing low-income countries showed that maternal aP immunization could be cost-saving in countries with low infant coverage, such as Nigeria, but very expensive in countries, such as Bangladesh, with high infant coverage.ConclusionA dynamic model, which captures the herd immunity benefits of pertussis vaccination, shows that, in low- and middle-income countries, maternal aP immunization is cost-effective when infant vaccination coverage is moderate, even cost-saving when it is low, but not cost-effective when coverage levels pass 90-95%.

Project description:ObjectivesUsing dynamic transmission models we evaluated the health and cost outcomes of adding acellular pertussis (aP) vaccination of pregnant women to infant vaccination in three Brazilian states that represent different socioeconomic conditions. The primary objective was to determine whether the same model structure could be used to represent pertussis disease dynamics in differing socioeconomic conditions.MethodsWe tested three model structures (SIR, SIRS, SIRSIs) to represent population-level transmission in three socio-demographically distinct Brazilian states: São Paulo, Paraná and Bahia. Two strategies were evaluated: infant wP vaccination alone versus maternal aP immunization plus infant wP vaccination. Model projections for 2014-2029 include outpatient and inpatient pertussis cases, pertussis deaths, years of life lost, disability-adjusted life-years (DALYs) lost, and costs (in 2014 USD) of maternal aP vaccination, infant vaccination, and pertussis medical treatment. Incremental cost per DALY averted is presented from the perspective of the Brazilian National Health System.ResultsBased on goodness-of-fit statistics, the SIRSIs model fit best, although it had only a modest improvement in statistical quantitative assessments relative to the SIRS model. For all three Brazilian states, maternal aP immunization led to higher costs but also saved infant lives and averted DALYs. The 2014 USD cost/DALY averted was $3068 in Sao Paulo, $2962 in Parana, and $2022 in Bahia. These results were robust in sensitivity analyses with the incremental cost-effectiveness ratios exceeding per capita gross regional product only when the probability that a pertussis case is reported was assumed higher than base case implying more overt cases and deaths and therefore more medical costs.ConclusionsThe same model structure fit all three states best, supporting the idea that the disease behaves similarly across different socioeconomic conditions. We also found that immunization of pregnant women with aP is cost-effective in diverse Brazilian states.

Project description:BackgroundMaternal Tetanus, diphtheria, and acellular pertussis (Tdap) vaccination provides antibody transfer to newborn infants and may affect their antibody response to the primary vaccination series. This study aimed to assess the effect of Tdap vaccination during pregnancy on infant antibody response to the whole cell pertussis (DTwP) primary series.MethodsPlasma from 318 pregnant women (243 Tdap-vaccinated and 75 unvaccinated) and their infants (cord blood) was collected at delivery; infant blood was again collected at 2 and 7 months, before and after their primary DTwP series. Anti-pertussis toxin (PT), pertactin (PRN), filamentous hemagglutinin (FHA), fimbriae 2/3 (FIM) and adenylate cyclase toxin (ACT) IgG antibodies were quantified by a microsphere-based multiplex antibody capture assay and anti-PT neutralizing antibodies by the Real Time Cell analysis system.ResultsInfant geometric mean concentrations (GMCs) of IgG anti-Tdap antigens were significantly higher (p < 0.001) among the Tdap-vaccinated (PT: 57.22 IU/mL; PRN: 464.86 IU/mL; FHA: 424.0 IU/mL), versus the unvaccinated group (4 IU/mL, 15.43 IU/mL, 31.99 IU/mL, respectively) at delivery. Anti-FIM and ACT GMCs were similar between the two groups. At 2 months of age, anti-PT, PRN, and FHA GMCs remained higher (p < 0.001) in the Tdap-vaccinated group (12.64 IU/mL; 108.76 IU/mL; 87.41 IU/mL, respectively) than the unvaccinated group (1.02 IU/mL; 4.46 IU/mL; 6.89 IU/mL). However, at 7 months, after receiving the third DTwP dose, the anti-PT GMC was higher (p = 0.016) in the unvaccinated group (7.91 IU/mL) compared to the vaccinated group (2.27 IU/mL), but without differences for anti-PRN, FHA, FIM and ACT GMCs.ConclusionElevated antibody levels suggest that maternal Tdap vaccination might protect infants until 2 months of age. Reduced anti-PT levels at 7 months indicate potential blunting of immune response in infants. Surveillance would help determine if blunting alters vaccine immunity and impacts pertussis prevention in infants.

Project description:ImportanceInfants younger than 1 year have the highest burden of pertussis morbidity and mortality. In 2011, the US introduced tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination during pregnancy to protect infants before vaccinations begin.ObjectiveTo assess the association of maternal Tdap vaccination during pregnancy with the incidence of pertussis among infants in the US.Design, setting, and participantsIn this ecologic study, a time-trend analysis was performed of infant pertussis cases reported through the National Notifiable Diseases Surveillance System between January 1, 2000, and December 31, 2019, in the US. Statistical analysis was performed from April 1, 2020, to October 31, 2022.ExposuresMaternal Tdap vaccination during pregnancy.Main outcomes and measuresPertussis incidence rates were calculated and compared between 2 periods-the pre-maternal Tdap vaccination period (2000-2010) and the post-maternal Tdap vaccination period (2012-2019)-for 2 age groups: infants younger than 2 months (target group of maternal vaccination) and infants aged 6 months to less than 12 months (comparison group). Incidence rate differences between the 2 age groups were modeled using weighted segmented linear regression. The slope difference between the 2 periods was estimated to assess the association of maternal Tdap vaccination with pertussis incidence among infants.ResultsA total of 57 460 pertussis cases were reported in infants younger than 1 year between 2000 and 2019; 19 322 cases (33.6%) were in infants younger than 2 months. During the pre-maternal Tdap vaccination period, annual pertussis incidence did not change among infants younger than 2 months (slope, 3.29 per 100 000 infants per year; P = .28) but increased slightly among infants aged 6 months to less than 12 months (slope, 2.10 per 100 000 infants per year; P = .01). There was no change in the difference in incidence between the 2 age groups (slope, 0.08 per 100 000 infants per year; P = .97) during the pre-maternal Tdap vaccination period overall. However, in the post-maternal Tdap vaccination period, incidence decreased among infants younger than 2 months (slope, -14.53 per 100 000 infants per year; P = .001) while remaining unchanged among infants aged 6 months to less than 12 months (slope, 1.42 per 100 000 infants per year; P = .29). The incidence rate difference between the 2 age groups significantly decreased during the post-maternal Tdap vaccination period (slope, -14.43 per 100 000 infants per year; P < .001). Pertussis incidence rate differences were significantly different between the pre-maternal and post-maternal Tdap vaccination periods (slope difference, -14.51 per 100 000 infants per year; P = .01).Conclusions and relevanceIn this study, following maternal Tdap vaccine introduction, a sustained decrease in pertussis incidence was observed among infants younger than 2 months, narrowing the incidence gap with infants aged 6 months to less than 12 months. These findings suggest that maternal Tdap vaccination is associated with a reduction in pertussis burden in the target age group (<2 months) and that further increases in coverage may be associated with additional reductions in infant disease.

Dataset Information

Comparison of static and dynamic models of maternal immunization to prevent infant pertussis in Brazil.

Background

Methods

Results

Conclusions

Clinical trial registry

Publications

Comparison of static and dynamic models of maternal immunization to prevent infant pertussis in Brazil.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets