Acceptability, Cost-Effectiveness, and Capacity of a Facility-Based Seasonal Influenza Vaccination: A Study in Selected Hospitals of Bangladesh

Background: Globally, seasonal influenza is a leading cause of morbidity and mortality with significant health and economic consequences. According to the World Health Organization (WHO), influenza affects around one billion people each year, with 3 to 5 million suffering from severe illness, leading to 290,000 to 650,000 deaths each year . The burden of influenza illness is significantly higher in low- and middle-income countries (LMICs) than in high-income countries (HIC) . Pregnant women, children under five years, and adults with co-morbid conditions in LMICs are more likely to get severe influenza illness. In a systematic review and meta-analysis of 27 studies found that elderly people were at higher risk of death and hospital admission during flu season. That study also found that pregnant women and children were at higher risk of developing pneumonia and requiring hospital admission; the adults with co-morbidity conditions were at risk of hospitalization and intensive care admission during flu seasons.

In order to prevent influenza infection and lessen the severity of the illness, in 2012, the WHO advised an annual influenza vaccine dosage for persons at high risk of acquiring a severe influenza illness. Despite the WHO recommendation of seasonal influenza vaccination prioritizing high-risk groups, 76% of the low-income countries, including Bangladesh, lack a national policy/programme on seasonal influenza targeting high-risk groups. Also, the lack of context-specific knowledge on the economic burden of influenza vaccines on high-risk groups, lack of medical, socio-behavioral patterns, and socio-economic consequences of influenza have been identified as challenges for promoting influenza vaccinations in LMICs.

In Bangladesh, around 25 million people of all ages sought outpatient treatment for influenza, where the yearly direct cost of influenza-associated outpatient visits was US$ 108 million. Moreover, approximately 30,592 laboratory-confirmed influenza patients of all ages were hospitalized each year, with an estimated annual influenza-associated hospitalization cost of US$ 1.4 million. Influenza vaccines are the most reliable method for preventing influenza infection. But unfortunately, Bangladesh does not have a national influenza vaccination program among the WHO-recommended high-risk population. The Ministry of Health and Family Welfare (MoH&FW), Government of the People's Republic of Bangladesh, only offers influenza vaccination to all Hajj pilgrims free of cost as part of the mandatory requirement for all Hajj pilgrims by the Saudi Government. However, there is a lack of information to drive the MoH&FW policy on influenza vaccinations in high-risk populations.

For reducing the influenza disease burden, particularly among high-risk populations, influenza vaccination has been proven to be the most effective and cost-effective approach. Immune responses elicited by influenza vaccines are generally strain-specific. Antibody against one influenza virus type or subtype generally confers limited or no protection against another type or subtype, nor does it typically confer protection against antigenic variants of the same virus that arise by antigenic drift. However, among adults, vaccination can cause a "back boost" of antibody titers against influenza A viruses that have been encountered previously either by vaccination or natural infection. Due to antigenic drift and shift, influenza vaccines are taken annually with an efficacy between 40-60% varies widely by setting and by influenza seasons. In addition, a systematic review of 118 studies on the cost-effectiveness of influenza vaccination revealed that 22 of the 118 studies showed influenza vaccination to be cost-saving. The study reported cost-effectiveness ratios of $10,000/outcome in 13 studies, $10,000 to $50,000 in 13 studies, and ≥$50,000 in 3 studies. Despite the fact that influenza vaccination was cost-effective, the cost-effectiveness parameters may not be applicable for all countries' contexts because of the differences in influenza disease profile, influenza vaccination unit costs, and health system delivery mechanisms. Hence, country-specific estimates are essential for the optimal allocation of scarce resources.

The investigators extensively searched influenza vaccination cost-effectiveness studies targeting high-risk populations in Bangladesh. But to date, there is scarce evidence in Bangladesh to inform policymakers about the acceptability, cost-effectiveness, and required capacity of influenza vaccination among the WHO-defined high-risk group population. Therefore, the investigators propose to generate preliminary data on high-risk groups' health beliefs, barriers, and intent to receive the influenza vaccine. The investigators will also generate preliminary data on the acceptability, cost-effectiveness, and required capacity for a facility-based influenza vaccination program to support policy decisions on influenza vaccination in Bangladesh among the high-risk population.