RSV is the most common cause of ALRI in children and an important cause of child mortality with a high disease burden in low and middle-income countries. The literature review summarized in this paper presents evidence required for making an informed decision on the research priority that should be given to emerging interventions against RSV. The scores for active and passive immunization of infants and pregnant women with interventions against the set criteria represent the collective optimism of a panel of experts drawn from varying technical backgrounds and affiliations. Although there are currently no vaccines to protect against the virus, significant progress is being made for active immunization, with live attenuated preparations looking most promising. Recent research has increased hope for a successful vaccine for infants as young as 2 months. However, there have been no trials in low and middle-income countries which are essential to assess their impact in these areas where disease burden is highest. Pharmaceutical companies would need to seriously consider undertaking future clinical trials in developing countries without which no progress in reducing global childhood mortality associated with RSV can be anticipated.
In the case of candidate vaccines for active immunization of infants against RSV, the experts expressed low levels of optimism for cost of product, affordability and low cost of development and implementation; moderate levels of optimism regarding the criteria of answerability, likelihood of efficacy, deliverability, sustainability and acceptance to end users for the interventions; and high levels of optimism regarding impact on equity and acceptance to health workers. While considering the candidate vaccines targeting pregnant women, the panel expressed low levels of optimism for cost of product, affordability, low cost of development and implementation, and even answerability; moderate levels of optimism for likelihood of efficacy, deliverability, sustainability and impact on equity; high levels of optimism regarding acceptance to end users and health workers. The group also evaluated immunoprophylaxis against RSV using monoclonal antibodies and expressed no optimism at all towards low product cost; low levels of optimism regarding deliverability, affordability, sustainability, cost of implementation and the impact on equity; moderate levels of optimism against the criteria of answerability, likelihood of efficacy, acceptance to end-users and health workers; and high levels of optimism regarding low development cost. As far as the vaccines against RSV are concerned the challenge would be to develop a low cost, immunogenic yet safe vaccine which can be either given to infants younger than two months of age or develop one which can be given to pregnant women in their last trimester.
This is the first time such an exercise has been conducted with the aim of predicting the future impact of emerging vaccines. The CHNRI methodology was primarily designed to evaluate existing interventions and competing investment priorities for health research. Although we used the CHNRI criteria, we modified it by including systematic review of available literature and not involving all stakeholders (e.g. end-users and health workers). The scores reported in this paper express the collective opinion of a panel of 20 experts. While there is always an element of error while predicting impact of interventions which do not exist and have no clinical trial data to support them (especially efficacy and maximum disease burden reduction potential), we feel that the results would be reproducible with another panel in a different setting.