Estimating the cost-effectiveness of maternal vaccination and monoclonal antibodies for respiratory syncytial virus in Kenya and South Africa

Attitude to RSV Vaccination Among a Cohort of Pregnant Women in Jordan: A Cross-Sectional Survey Study

Background and Aims

The recently approved maternal vaccination against respiratory syncytial virus (RSV) can reduce its burden among infants. However, vaccine hesitancy/resistance can undermine the beneficial impact of RSV vaccination. The aim of this study was to assess the willingness of pregnant women in Jordan to receive RSV vaccination and its associated determinants.

Methods

Face-to-face interviews were conducted in obstetrics/gynecology clinics in the Central, Northern, and Southern regions of Jordan during January-February 2024, using a convenience sampling approach. Attitude to RSV vaccination was assessed using the previously validated ABCDEF scale.

Results

A total of 404 pregnant women participated in the study with a mean age of 30.1 ± 6.2 years. A majority of the participants showed willingness to receive RSV vaccination (n = 313, 77.5%), with hesitancy among 25 participants (6.2%), and resistance among 66 participants (16.3%). Variables that were significantly associated with a higher RSV vaccine acceptance in multivariate analysis were: age < 30 years (adjusted odds ratio (aOR): 2.45, p = 0.010), undergraduates (aOR: 3.27, p = 0.026), being a healthcare worker (aOR: 4.50, p = 0.036), and the history of previous COVID-19/influenza vaccine uptake (aOR: 2.47, p = 0.045). Two out of the six ABCDEF constructs were significantly associated with RSV vaccine acceptance, namely the "Advice" construct (aOR: 10.38, p < 0.001) and the "Fear" construct (aOR: 21.49, p < 0.001).

Conclusion

This study highlighted the complex nature of attitude towards maternal RSV vaccination among pregnant women. The study showed the role of demographic variables, prior vaccination experience, trust in credible health institutions and vaccine safety, and the fear of RSV disease consequences in infants in shaping maternal attitude to RSV vaccination. Addressing these factors can help to effectively promote RSV vaccine uptake among pregnant women, subsequently helping to protect infants from the significant RSV disease burden.

From setbacks to success: lessons from the journey of RSV vaccine development

Respiratory syncytial virus (RSV) causes high worldwide infant mortality, as well as a high disease burden in the elderly. Efforts in vaccine development over the past 60 years have recently delivered three approved vaccines and two monoclonal antibodies (mAbs). Looking back at the eventful history of RSV vaccine development, several factors can be identified that have hampered the developmental pathway, including the occurrence of enhanced RSV disease (ERD) in the first vaccine attempt and the difficulty in characterizing and stabilizing the pre-fusion F protein as a vaccine target. Moreover, the need for large trials to test vaccine efficacy, usually done late in development, and the lack of a correlate of protection (CoP) result in significant uncertainties in RSV vaccine development. The use of controlled human infection models (CHIMs) may provide a solution for some of these problems: through swift, cost-efficient and closely monitored assessment of vaccine safety and efficacy in early clinical phases, vaccines can either 'fail fast' or show results supporting further investments. Moreover, CHIMs facilitate the assessment of disease and could assist in the identification of a CoP supporting late-stage development. Although some factors may affect translatability to real-world vaccine efficacy, CHIMs can support the clinical development pathway in various ways. We advocate for, and demonstrate, a conceptual and rational design of RSV vaccine development. Assessing protective efficacy early on would result in the most cost-efficient pathway and identification of target populations should be done as early as possible. For RSV, elderly individuals and people in low- and middle-income countries are high-impact populations for RSV prevention. While RSV immunization is now available in certain regions, global access is not accomplished yet, and worldwide prevention does not seem within reach. Quick and cost-effective assessments of candidates currently in the pipeline could contribute to future successes in the battle against RSV.

The respiratory syncytial virus vaccine and monoclonal antibody landscape: the road to global access

Respiratory syncytial virus (RSV) is the second most common pathogen causing infant mortality. Additionally, RSV is a major cause of morbidity and mortality in older adults (age ≥60 years) similar to influenza. A protein-based maternal vaccine and monoclonal antibody (mAb) are now market-approved to protect infants, while an mRNA and two protein-based vaccines are approved for older adults. First-year experience protecting infants with nirsevimab in high-income countries shows a major public health benefit. It is expected that the RSV vaccine landscape will continue to develop in the coming years to protect all people globally. The vaccine and mAb landscape remain active with 30 candidates in clinical development using four approaches: protein-based, live-attenuated and chimeric vector, mRNA, and mAbs. Candidates in late-phase trials aim to protect young infants using mAbs, older infants and toddlers with live-attenuated vaccines, and children and adults using protein-based and mRNA vaccines. This Review provides an overview of RSV vaccines highlighting different target populations, antigens, and trial results. As RSV vaccines have not yet reached low-income and middle-income countries, we outline urgent next steps to minimise the vaccine delay.

Early-life respiratory syncytial virus disease and long-term respiratory health

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection (LRTI), hospital admission, and mortality in children worldwide. Early-life RSV LRTI has also been associated with subsequent long-term respiratory sequelae, including recurrent LRTI, recurrent wheezing, asthma, and lung function impairment, and these effects can persist into adulthood as chronic respiratory disease. New preventive measures (maternal vaccine or long-acting monoclonal antibodies) have been licensed to reduce the burden of acute RSV LRTI in infants and children at high risk through passive immunisation. Studies of these RSV prevention products show high efficacy and effectiveness, particularly for preventing severe RSV LRTI, with implementation in many high-income countries, but limited access in low-income and middle-income countries (LMICs). These interventions might also reduce the risk of additional health outcomes and long-term morbidity. This Series paper provides the evidence for the long-term effects of early-life RSV disease, discusses mechanisms of disease development, and addresses the potential full public health value of prevention of RSV illness. Further research is needed to determine whether prevention of RSV LRTI or delay of RSV illness in early life might prevent or ameliorate the development of associated long-term respiratory disease. This potential further underscores the urgency for access and availability of new interventions to prevent early-life RSV LRTI in LMICs.

Respiratory syncytial virus vaccination and immunoprophylaxis: realising the potential for protection of young children

The search for safe and efficacious products to prevent severe respiratory syncytial virus (RSV) disease in young infants has lasted more than 60 years. In high-income and middle-income countries, two new products have been authorised: an RSV monoclonal antibody for administration to infants (nirsevimab) and an RSV prefusion F maternal vaccine (RSVpreF [Pfizer, Puurs, Belgium]) for administration to pregnant people. These products are not yet available in low-income and lower-middle-income countries, where most RSV deaths occur. Other papers in this Series describe the acute burden of RSV disease in young children, the effects of RSV infection in early childhood on long-term lung health, and the burden of RSV disease and disease prevention products in older adults. In this Series paper, we briefly review the efficacy, effectiveness, and safety of nirsevimab and RSVpreF maternal vaccine for protection of infants. We then explore potential regulatory, policy, and implementation pathways and provide case studies of intervention uptake in Spain and Argentina, and considerations for use in Kenya. We also explore the health economic evidence to inform product introduction decisions. With sufficient political will and affordable pricing, RSV disease prevention in infants can become a global reality.

The cost of care for children hospitalized with respiratory syncytial virus (RSV) associated lower respiratory infection in Kenya

BACKGROUND

Respiratory syncytial virus (RSV) is one of the main causes of hospitalization for lower respiratory tract infection in children under five years of age globally. Maternal vaccines and monoclonal antibodies for RSV prevention among infants are approved for use in high income countries. However, data are limited on the economic burden of RSV disease from low- and middle-income countries (LMIC) to inform decision making on prioritization and introduction of such interventions. This study aimed to estimate household and health system costs associated with childhood RSV in Kenya.

METHODS

A structured questionnaire was administered to caregivers of children aged < 5 years admitted to referral hospitals in Kilifi (coastal Kenya) and Siaya (western Kenya) with symptoms of acute lower respiratory tract infection (LRTI) during the 2019-2021 RSV seasons. These children had been enrolled in ongoing in-patient surveillance for respiratory viruses. Household expenditures on direct and indirect medical costs were collected 10 days prior to, during, and two weeks post hospitalization. Aggregated health system costs were acquired from the hospital administration and were included to calculate the cost per episode of hospitalized RSV illness.

RESULTS

We enrolled a total of 241 and 184 participants from Kilifi and Siaya hospitals, respectively. Out of these, 79 (32.9%) in Kilifi and 21(11.4%) in Siaya, tested positive for RSV infection. The total (health system and household) mean costs per episode of severe RSV illness was USD 329 (95% confidence interval (95% CI): 251-408 ) in Kilifi and USD 527 (95% CI: 405- 649) in Siaya. Household costs were USD 67 (95% CI: 54-80) and USD 172 (95% CI: 131- 214) in Kilifi and Siaya, respectively. Mean direct medical costs to the household during hospitalization were USD 11 (95% CI: 10-12) and USD 67 (95% CI: 51-83) among Kilifi and Siaya participants, respectively. Observed costs were lower in Kilifi due to differences in healthcare administration.

CONCLUSIONS

RSV-associated disease among young children leads to a substantial economic burden to both families and the health system in Kenya. This burden may differ between Counties in Kenya and similar multi-site studies are advised to support cost-effectiveness analyses.

Maternal Vaccination for the Prevention of Infantile RSV Disease: An Overview of the Authorized, In-Progress, and Rejected Vaccine Candidates

Respiratory Syncytial Virus (RSV) continues to pose a significant challenge, contributing to elevated hospitalization rates among children up to 5 years old, with a disproportionate burden on newborns and infants under 6 months old. The unique characteristics of the young immune system make it prone to altered responses to infections and vaccinations, requiring a tailored approach to disease prevention. The recent approval of the maternal RSV vaccine (brand name ABRYSVO) represents a pivotal advancement in preventive strategies among newborns and infants, marking a milestone in RSV research as the first market-approved maternal vaccine. The present review examines clinical trial data on both recent and previous vaccine candidates, as well as the licensed vaccine, focusing on the prevention of RSV disease in newborns and young infants through the passive acquisition of antibodies following maternal immunization. Additionally, it evaluates the safety profile of these vaccines.

Respiratory syncytial virus-associated pneumonia in primary care in Malawi

OBJECTIVE

To identify the prevalence of respiratory syncytial virus (RSV) in a cohort of children under 5 years of age with World Health Organization (WHO)-defined pneumonia and the factors associated with developing severe RSV-associated community-acquired pneumonia (CAP) in primary care in a single centre in Northern Malawi.

METHODS

The BIOmarkers TO diagnose PnEumonia (BIOTOPE) study was a prospective cohort study conducted from March to June 2016 that took place in a primary care centre in Northern Malawi. Data from this study was used to identify the characteristics of children under 5 years of age who presented with RSV and WHO-defined CAP. Means, standard deviations, medians and ranges were calculated for continuous variables. A univariate logistic regression was performed to examine the potential predictor variables.

RESULTS

Four hundred and ninety-four infants presented with CAP and were eligible for inclusion in the study; RSV infection was detected in 205 (41.6%) of the infants. Eight factors were associated with increased risk for RSV CAP in the univariate model: age, born at term, presenting for care in June, crowded living environment, not being exclusively breastfed, not having received zinc or vitamin A supplementation in the last six months. Infants with RSV were more likely to have an oxygen saturation ≤92% compared to infants with other causes of pneumonia and more likely to have severe pneumonia as defined by the WHO.

CONCLUSION

This study supports that RSV-associated CAP is linked to modifiable and non-modifiable risk factors; further research is indicated to determine which interventions would be most impactful. Developing and implementing an infant or maternal vaccine could be a cost-effective way to prevent RSV-associated CAP and mortality in developing nations. More research is needed to understand seasonal patterns of CAP and research over extended periods can offer valuable insights on host, environmental and pathogen-specific factors that contribute to RSV-associated CAP.

The full value of immunisation against respiratory syncytial virus for infants younger than 1 year: effects beyond prevention of acute respiratory illness

Respiratory syncytial virus (RSV) is a leading cause of severe respiratory illness and death among children worldwide, particularly in children younger than 6 months and in low-income and middle-income countries. Feasible and cost-effective interventions to prevent RSV disease are not yet widely available, although two new products aimed at preventing RSV disease-long-acting monoclonal antibodies and maternal vaccines-have been licensed within the past 2 years. The primary target of these products is reduction of the substantial burden of RSV-associated acute lower respiratory tract infections (LRTI) in infants younger than 1 year. However, other important public health benefits might also accrue with the prevention of RSV-associated LRTI during the first year of life. Mounting evidence shows that preventing RSV-associated LRTI in infants younger than 1 year could prevent secondary pneumonia caused by other pathogens, reduce recurrent hospitalisations due to other respiratory diseases in later childhood, decrease all-cause infant mortality, ameliorate the burden of respiratory diseases on health-care systems, reduce inappropriate antibiotic use, and possibly improve lung health beyond infancy. We herein review current evidence and suggest approaches to better assess the magnitude of these potential secondary effects of RSV prevention, which, if proven substantial, are likely to be relevant to policy makers in many countries as they consider the use of these new products.

Exploratory analysis of the economically justifiable price of nirsevimab for healthy late-preterm and term infants in Colombia

INTRODUCTION

Respiratory syncytial virus infection is the leading cause of lower respiratory infection globally. Recently, nirsevimab has been approved to prevent respiratory syncytial virus (RSV) infection. This study explores the economically justifiable price of nirsevimab for preventing RSV infection in Colombia's children under 1 year of age.

MATERIALS AND METHODS

A static model was developed using the decision tree microsimulation to estimate the quality-adjusted costs and life years of two interventions: a single intramuscular dose of nirsevimab versus not applying nirsevimab. This analysis was made during a time horizon of 1 year and from a societal perspective.

RESULTS

The annual savings in Colombia associated with this cost per dose ranged from U$ 2.5 to 4.1 million. Based on thresholds of U$ 4828, U$ 5128, and U$ 19 992 per QALY evaluated in this study, we established economically justifiable drug acquisition prices of U$ 21.88, U$ 25.04, and U$ 44.02 per dose of nirsevimab.

CONCLUSION

the economically justifiable cost for nirsevimab in Colombia is between U$ 21 to U$ 44 per dose, depending on the willingness to pay used to decide its implementation. This result should encourage more studies in the region that optimize decision-making processes when incorporating this drug into the health plans of each country.

Maternal awareness, acceptability and willingness towards respiratory syncytial virus (RSV) vaccination during pregnancy in Ireland

BACKGROUND

Respiratory syncytial virus (RSV) is the world's leading cause of viral acute lower respiratory infections (ALRI) in infants. WHO has identified maternal RSV vaccination a priority and candidate vaccines are in development; however, vaccine hesitancy remains an impediment to successful implementation of maternal immunization. This study, the largest antenatal survey conducted to-date, aimed to examine maternal RSV awareness, likely acceptance of RSV vaccination in pregnancy, and attitudes to maternal vaccination.

METHODS

Pregnant women of all gestations attending antenatal clinic of a university maternity hospital in Ireland were invited to participate. An information leaflet provided, consent obtained, and survey administered examining RSV awareness, willingness to avail of antenatal RSV vaccination, factors influencing acceptability and preferred sources of assistance. Research Ethics Committee (REC) approval obtained, and general data protection regulation (GDPR) guidelines followed.

RESULTS

528 women completed the survey. A large proportion (75.6%) had never heard of RSV, yet 48.5% would still avail of a vaccine, 45.8% were undecided and only 5.3% would not. The main factor making vaccination acceptable to women (76.4%) was that it protects their infant from illness (p < .001, CV 0.336 for association with acceptance) and general practitioner (GP) was the preferred guidance source in decision-making (57.7%).

CONCLUSIONS

Despite low levels of maternal awareness of RSV, pregnant women in Ireland are open to availing of antenatal vaccination. Maternal immunization strategies need to focus on infant's protection from RSV-associated ALRI along with vaccine safety, and build on an interdisciplinary collaboration of maternal, neonatal, primary care and public health services.

Vaccination for Respiratory Syncytial Virus: A Narrative Review and Primer for Clinicians

Respiratory syncytial virus (RSV) poses a significant burden on public health, causing lower respiratory tract infections in infants, young children, older adults, and immunocompromised individuals. Recent development and licensure of effective RSV vaccines provide a promising approach to lessening the associated morbidity and mortality of severe infections. This narrative review aims to empower clinicians with the necessary knowledge to make informed decisions regarding RSV vaccination, focusing on the prevention and control of RSV infections, especially among vulnerable populations. The paper explores the available RSV vaccines and existing evidence regarding their efficacy and safety in diverse populations. Synthesizing this information for clinicians can help the latter understand the benefits and considerations associated with RSV vaccination, contributing to improved patient care and public health outcomes.

Cost-effectiveness analysis of nirsevimab and maternal RSVpreF vaccine strategies for prevention of Respiratory Syncytial Virus disease among infants in Canada: a simulation study

Background

The cost-effectiveness of immunisation strategies with a long-acting monoclonal antibody (nirsevimab) and/or a protein-based maternal vaccine (RSVpreF) for protecting infants from Respiratory Syncytial Virus (RSV)-associated illness has not been previously determined for Canada. We estimated the health benefits and cost-effectiveness of nirsevimab for immunising the entire birth cohort, regardless of gestational age or other risk factors. Additionally, we evaluated the health benefits and cost-effectiveness of a combined strategy of year-round vaccination of pregnant women with RSVpreF and immunisation of infants at high risk, including those born preterm or with chronic conditions, with nirsevimab during the RSV season.

Methods

We developed a discrete-event simulation model, parameterized with the data on medically-attended RSV infections among infants under one year of age from 2010 to 2019, including outpatient care, hospitalisations, and deaths. Intervention scenarios targeting twelve monthly birth cohorts and pregnant women, reflecting the 2021 census data for Ontario, Canada were evaluated over a follow-up time horizon of one year from birth. Taking into account the costs (in 2023 Canadian dollars) associated with RSV-related outcomes, we calculated the net monetary benefit using the quality-adjusted life-year (QALY) gained. Further, we determined the range of price-per-dose (PPD) for nirsevimab and RSVpreF within which the program was cost-effective. Cost-effectiveness analyses were conducted from both healthcare and societal perspectives.

Findings

Using a willingness-to-pay of CAD$50,000 per QALY gained, we found that immunising the entire birth cohort with nirsevimab would be cost-effective from a societal perspective for a PPD of up to $290, with an annual budget impact of $83,978 for 1113 infants per 100,000 population. An alternative, combined strategy of vaccinating pregnant women and immunising only infants at high risk of severe disease would lead to a lower budget impact of $49,473 per 100,000 population with a PPD of $290 and $195 for nirsevimab and RSVpreF vaccine, respectively. This combined strategy would reduce infant mortality by 76%-85%, comparable to a 78% reduction achieved through a nirsevimab-only program of the entire birth cohort. The PPD for cost-effective programs with nirsevimab was sensitive to the target population among infants.

Interpretation

Passive immunisation of infants under 6 months of age with nirsevimab and vaccination of pregnant women with RSVpreF could be a cost-effective strategy for protecting infants during their first RSV season.

Funding

This study was supported by the Canadian Immunisation Research Network (CIRN) and the Canadian Institutes of Health Research (CIHR). Seyed M. Moghadas acknowledges support from the Natural Sciences and Engineering Research Council of Canada (MfPH and Discovery grants). Alison P. Galvani acknowledges support from the The Notsew Orm Sands Foundation.

Report of the WHO technical consultation on the evaluation of respiratory syncytial virus prevention cost effectiveness in low- and middle-income countries, April 7-8, 2022

Policymakers often rely on impact and cost-effectiveness evaluations to inform decisions about the introduction of health interventions in low- and middle-income countries (LMICs); however, cost-effectiveness results for the same health intervention can differ by the choice of parameter inputs, modelling assumptions, and geography. Anticipating the near-term availability of new respiratory syncytial virus (RSV) prevention products, WHO convened a two-day virtual consultation in April 2022 with stakeholder groups and global experts in health economics, epidemiology, and vaccine implementation. The objective was to review methods, parameterization, and results of existing cost-effectiveness analyses for RSV prevention in LMICs; identify the most influential inputs and data limitations; and recommend and prioritize future data gathering and research to improve RSV prevention impact estimates in LMICs. Epidemiological parameters identified as both influential and uncertain were those associated with RSV hospitalization and death, specifically setting-specific hospitalization rates and RSV-attributable death rates. Influential economic parameters included product price, delivery costs, willingness-to-pay for health on the part of potential donors, and the cost of RSV-associated hospitalization. Some of the influential parameters identified at this meeting should be more precisely measured by further research. Other influential economic parameters that are highly uncertain may not be resolved, and it is appropriate to use sensitivity analyses to explore these within cost-effectiveness evaluations. This report highlights the presentations and major discussions of the meeting.