Is adding maternal vaccination to prevent whooping cough cost-effective in Australia?

How are maternal and fetal outcomes incorporated when measuring benefits of interventions in pregnancy? Findings from a systematic review of cost-utility analyses

OBJECTIVE

Medical interventions used in pregnancy can affect the length and quality of life of both the pregnant person and fetus. The aim of this systematic review was to identify and describe the theoretical frameworks that underpin outcome measurement in cost-utility analyses of pregnancy interventions.

METHODS

Searches were conducted in the Paediatric Economic Database Evaluation (PEDE) database (up to 2017), as well as Medline, Embase and EconLit (2017-2019). We included all cost-utility analyses of any intervention given during pregnancy, published in English. We conducted a narrative synthesis of: study design; outcome construction (life expectancy, quality adjustment, discount rate); and whether the Incremental Cost-Effectiveness Ratio (ICER) was constructed using maternal or fetal outcomes. Where both outcomes were included, methods for combining them were extracted.

RESULTS

We identified 127 cost-utility analyses in pregnancy, of which 89 reported QALYs and 38 DALYs. Outcomes were considered solely for the fetus in 59 studies (47%), solely for the pregnant person in 13 studies (10%), and for both in 49 studies (39%). The choice to include or exclude one or both sets of outcomes was not consistent within particular clinical areas. Where outcomes for both mother and baby were included, methods for combining these outcomes varied. Twenty-nine studies summed QALYs/DALYs for maternal and fetal outcomes, with no adjustment. The remaining 20 took a variety of approaches designed to weigh maternal and fetal outcomes differently. These include (1) treating fetal outcomes as a component of maternal quality of life, rather than (or in addition to) an independent individual health outcome; (2) treating the maternal-fetal dyad as a single entity and applying a single utility value to each combination of outcomes; and (3) assigning a shorter time horizon to fetal outcomes to reduce the weight of lifetime fetal outcomes. Each approach made different assumptions about the relative value of maternal and fetal health outcomes, demonstrating a lack of consistency and the need for guidance.

CONCLUSION

Methods for capturing QALY/DALY outcomes in cost-utility analysis in pregnancy vary widely. This lack of consistency indicates a need for new methods to support the valuation of maternal and fetal health outcomes.

Maternal immunization: trends in South and Southeast Asian countries

Maternal immunization has the potential to reduce neonatal deaths caused by vaccine-preventable infectious diseases. Elimination of maternal and neonatal tetanus from many countries illustrates the potential benefits of maternal immunization as a strategy to decrease neonatal mortality caused by vaccine-preventable infections. Many countries in South and Southeast Asia have high cases of neonatal deaths, which were historically attributed to vaccine-preventable infections. Still, these countries vary in recommendations regarding immunization of pregnant women. We reviewed the current recommendations for the use of tetanus toxoid, tetanus-diphtheria, or tetanus-diphtheria-acellular pertussis (Tdap) vaccines for immunization of pregnant women. In addition to protection against tetanus and diphtheria, administration of the Tdap vaccine to pregnant women could help protect neonates against pertussis until they can receive the first two vaccine doses of their primary course. Vaccination against seasonal influenza is also recommended in many countries worldwide for pregnant women as influenza can pose health risks for the mother-fetus unit and the infant. Despite the recognized benefit of influenza vaccination for pregnant women, only some South and Southeast Asian countries have implemented its recommendation. The success of maternal tetanus vaccination has kindled the interest in vaccines that can be safely administered during pregnancy. Future availability of vaccines against respiratory syncytial virus and group B streptococcus, for use in pregnant women, could help prevent neonatal infections, especially in regions where diseases are less controlled. Communicating the body of evidence that supports maternal immunization to obstetricians is key for achieving optimal vaccination coverage to ensure protection of neonates. The current review aims to create awareness about the existing and potential benefits of maternal immunization in South and Southeast Asia.

Modeling the cost-effectiveness of maternal acellular pertussis immunization (aP) in different socioeconomic settings: A dynamic transmission model of pertussis in three Brazilian states

OBJECTIVES

Using 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.

METHODS

We 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.

RESULTS

Based 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.

CONCLUSIONS

The 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.

Control of vaccine preventable diseases in Australian infants: reviewing a decade of experience with DTPa-HBV-IPV/Hib vaccine

The combined vaccine against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, and Haemophilus influenzae b (DTPa-HBV-IPV/Hib, Infanrix Hexa, GSK) has been used for childhood immunization in Australia according to a two-, four-, six-month schedule since 2009. We reviewed data available in the Australian National Notifiable Diseases Surveillance System, annual vaccination coverage reports, the Database of Adverse Event Notifications, and peer-reviewed literature to assess vaccine coverage rates, incidence of all six vaccine preventable diseases, and the safety profile of DTPa-HBV-IPV/Hib vaccine in Australian infants over a period of ten years of exclusive use. Between 2009 and 2018 vaccine coverage for infants aged 12 months increased from 91.7% to 94.0% and from 84.9% to 92.6% for all and for Indigenous infants, respectively. Over the same time period, there were no reports of poliomyelitis, diphtheria or tetanus in infants <12 months of age. The incidence of hepatitis B among Australian infants <12 months of age remains 10 to 20-fold lower than the national average. Control of Haemophilus influenzae b (Hib) and pertussis disease has continued to be challenging. Timely administration of the primary series, as well as increasing coverage rates, particularly among Indigenous children, has contributed to improvements in Hib and pertussis disease control. The incorporation of additional strategies such as adjustment of the first vaccination encounter to six weeks of age, parental cocooning, and most recently maternal vaccination has further reduced the burden of pertussis, particularly during the first six months of life. The frequency of the ten most common adverse events related to the DTPa-HBV-IPV/Hib vaccine demonstrates an acceptable safety profile. Data collected over ten years of consistent, exclusive use of the DTPa-HBV-IPV/Hib vaccine in Australia highlights combination vaccination as a cornerstone in maintaining infant health.

Effectiveness of strategies to increase uptake of pertussis vaccination by new parents and family caregivers: A systematic review

OBJECTIVES

Cocoon immunisation strategies involve administration of Bordetella pertussis containing vaccines to parents and family members who are in close contact with newborns. The objective of this systematic review was to evaluate the effectiveness of strategies to increase uptake of vaccination against Bordetella pertussis infection by parents and family caregivers of newborn children (< 3 months of age).

DESIGN

A protocol driven systematic review was conducted between 2005 and February 2020. CINAHL, Medline, and Google Scholar databases were searched.

SETTING

Inpatient maternity care units, ante-natal and post-natal clinics based in acute care or primary/community care contexts.

PARTICIPANTS

(i) mothers, (ii) fathers and (iii) family caregivers or other regular household contacts of infants < 3 months of age.

INTERVENTIONS

Health promotion interventions and immunisation clinics designed to promote "cocoon immunisation" against Bordetella pertussis infections of the newborn.

MEASUREMENTS

Change in uptake of adult vaccination with a pertussis containing vaccine (dTpa or Tdap) by new parents and family caregivers.

FINDINGS

Eight studies were included in this review. Strategies used to promote vaccination included: written and verbal education, promotional videos, provision of vaccine prescriptions and financial incentives, opportunistic vaccination of family members and population-based health promotional messaging. Six of the eight studies reported positive impacts on vaccination uptake. Four studies evaluating providing opportunistic immunisation during the obstetric admission reported statistically significant increases in maternal (+39% to +57%), paternal (+21% to +52%) and household members (+32%) vaccination rates. Targeted public health campaigns were also found to increase vaccination uptake but in isolation were insufficient to achieve vaccination of all household contacts.

CONCLUSION

Promotion of pertussis vaccination to new parents and the provision of opportunistic vaccination during the obstetric admission or post-natal visit, was the most successful strategy to increase uptake of pertussis vaccination by family caregivers.

The problem of pertussis in some regions of the world

Pertussis infection remains a high-priority issue both for Russian health care and abroad. A rise of pertussis incidence in various human age groups instigates a search for new ways to fight this infection and improve methods for its laboratory diagnostics. By taking into consideration a short-term effect induced by acellular and whole-cell vaccines, a feasibility of introducing the second or even the third pertussis revaccination is vigorously debated. Objective of the study was to analyze the experience and effectiveness of acellular pertussis vaccines in countries, which use the second and third pertussis revaccination in the National Immunization Schedule in order to have an insight into adjusting strategy and tactics of pertussis immunization In Russia. Analyzing pertussis prevalence demonstrated that despite a wide immunization coverage pertussis incidence in the last years (2008–2015) was increased in a large number of countries in the European region, as well as inAustralia,CanadaandUSA. However, the reasons for elevated pertussis incidence have not been clarified yet. On one hand, it may be accounted for by low vaccination coverage in adolescents and adults; weakened immune protection after vaccination; genetic changes in Bordetella pertussis; shortened durability of protective immunity in children vaccinated with acellular vs. whole-cell vaccine; improved monitoring and morbidity reporting, as well as improved laboratory diagnostics due to shifting from serological and bacteriological to molecular genetic assays. In an attempt to solve this issue, researchers from several countries collaborate to discuss and develop a strategy to reduce pertussis incidence. ForRussia, the most important is to empower and/or improve existing infant immunization strategy in order to provide wide coverage with the four dose pertussis vaccine for decreasing the risk of pertussis morbidity and mortality. It is worth noting the “cocoon” strategy given the high risk of pertussis infection in children of the first months of life. We believe that forRussiait is worth investigating an opportunity of using children 2–3 months of life an acellular vaccine as the first vaccination, which is expected to increase the coverage of this cohort and allow to increase proportion of children who might complete vaccination by 5 months of age. At the same time, more reasonable might be to preserve a number of age groups for pertussis vaccination in the current National Immunization Schedule, as expanding age limits for vaccination might put a risk at increasing pertussis morbidity in older individuals, which could be hard to diagnose.