Replacing only 10% of seasonal vaccines with a universal flu vaccine could prevent 5.3 million cases and 6,300 deaths annually
Influenza is responsible for considerable disease and deaths worldwide, including an estimated 291,000 to 646,000 deaths annually; Effectiveness of influenza vaccines in preventing infections has ranged from 19 to 60% over the last nine seasons
An estimated 5.3 million cases and 6,300 deaths can be prevented every year by replacing just 10% of typical seasonal influenza vaccines with a universal vaccine, which is 75% effective.
These results — according to researchers from the Center for Infectious Disease Modeling and Analysis, Yale School of Public Health; Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Department of Integrative Biology, University of Texas at Austin; and Emerging Pathogens Institute, University of Florida — highlight the enormous value of an investment in the research and development of universal influenza vaccines.
The first clinical trial of a universal influenza vaccine — being conducted at the NIH Clinical Center in Bethesda, Maryland — is currently analyzing its safety and tolerability. Scientists at the National Institute of Allergy and Infectious Diseases (NIAID), which is part of the National Institutes of Health, have developed the experimental vaccine, called H1ssF_3928. The idea behind a universal influenza vaccine is to provide long-lasting protection for all age groups from multiple influenza subtypes, including those that might cause a pandemic.
There are four types of seasonal influenza viruses: types A, B, C and D. Influenza A, and B viruses circulate and cause seasonal epidemics of disease. Influenza can cause severe illness or death, particularly in people at high risk, says the World Health Organization (WHO). Illnesses range from mild to severe and even death. Hospitalization and death occur mainly among high-risk groups.
Influenza is responsible for considerable disease and deaths worldwide, including an estimated 291,000 to 646,000 deaths annually. In the US, an average of 28.41 million cases, 461,111 hospitalizations, and 40,500 influenza-related deaths occurred each year over the last nine years. The economic burden of influenza has been estimated at $5.8 billion annually, accounting for 65% of the burden from all vaccine-preventable diseases in the US, says the research team.
Influenza viruses mutate constantly, so the strains that circulate differ from one year to the other. Accordingly, vaccines are reformulated annually based on forecasts informed by viral surveillance in over 100 countries. While vaccination is the primary intervention for influenza prevention and control, the efficacy of the seasonal vaccine has ranged from 19 to 60% during the last nine seasons, says the research team.
“Using a model of influenza transmission, we evaluated the population-level impacts of universal influenza vaccines distributed according to empirical age-specific coverage at multiple scales in the US,” says the team.
They further say, “We estimate that replacing just 10% of typical seasonal vaccines with 75% efficacious universal vaccines would avert approximately 5.3 million cases, 81,000 hospitalizations, and 6,300 influenza-related deaths per year. This would prevent over $1.1 billion in direct health care costs compared to a typical season, based on average data from the 2010–11 to 2018–19 seasons.” The findings have been published in the Proceedings of the National Academy of Sciences (PNAS).
According to the research team, these health and economic savings would increase as a larger proportion of seasonal vaccines is replaced with universal vaccines. For example, replacing half of the typical seasonal vaccines with universal vaccines would avert 15.1 million cases, 226,823 hospitalizations, and 17,664 deaths. It would also save $3.2 billion in direct medical costs.
A complete replacement of seasonal vaccines with universal vaccines is projected to prevent 17 million cases, 251,000 hospitalizations, 19,500 deaths, and $3.5 billion in direct healthcare costs, shows analysis.
“The efficacy of influenza vaccines, currently at 44%, is limited by the rapid antigenic evolution of the virus and a manufacturing process that can lead to vaccine mismatch. We found that universal vaccines meeting the 75% efficacy goal set by the NIAID would have the potential to avert considerable incidence, hospitalizations, deaths, and economic burden, beyond the protection provided by current seasonal vaccines,” says the team.
According to the analysis, a universal vaccine is expected to be most impactful for reducing incidence among school-age children and for mitigating severe health outcomes and medical costs in the elderly. School-age children have the highest annual incidence of influenza infections, contributing over 26.5% of cases despite accounting for only 19% of the population. “Replacing half of the typical seasonal vaccines with universal vaccines would avert 4.1 million cases among school-age children. Complete replacement of seasonal vaccines with universal vaccines would further avert 430,000 cases, reducing the incidence rate among school-age children to only 4% of what is expected during a typical influenza season,” estimates suggest.
In the case of the elderly population, the study estimates that replacing half of the typical seasonal vaccines with a universal vaccine would stop 195,131 hospitalizations and 16,231 deaths among this age class. This would reduce direct medical costs due to these severe medical outcomes by over 85%. Switching entirely to universal vaccines would almost eliminate influenza transmission, further preventing 20,453 hospitalizations and 1,728 deaths, saving a total of $2.4 billion of direct medical costs in the elderly, says the study.
States with high hospitalization costs and elderly population would experience the greatest economic benefits from such a vaccine. “We found that universal vaccines would have the greatest impact on reducing incidence for states with high vaccination coverage. For example, replacing seasonal vaccines with universal vaccines would avert the most incidence per capita in South Dakota, Rhode Island, Massachusetts, and Maryland. Vaccination coverage in each of these states exceeds 50% compared with the national average of 45.6%,” says the study.
The most dramatic reduction in severe clinical outcomes is projected for states that have high vaccination coverage as well as a greater proportion of older adults (over 50-plus years). For example, universal vaccines would have the most significant impact on preventing hospitalizations and deaths in West Virginia, Maine, and Delaware. In each of these states, vaccination coverage is higher than 47.5%, and older people (50-plus years) comprise over 38% of the population. Nationally, this age class constitutes only 35.4% of the population.
The WHO identifies an influenza pandemic as one of the top 10 threats to global health in 2019. “If a universal influenza vaccine protects against any pandemic influenza strain, that would eliminate delays in the production of a vaccine against the specific pandemic strain and avoid the risks associated with using the seasonal vaccine during a pandemic,” the findings state.
Estimates show that the direct medical costs due to influenza exceed $3.7 billion annually. This does not include productivity losses due to illness. Hence, the annual $200 million proposed by the Flu Vaccine Act represent only a fraction of current influenza-related costs, says the team.
“Our estimates of the economic impact of universal vaccines, therefore, justify the substantial costs of developing a new vaccine. Besides, universal vaccines would save time and money spent each year in reformulating current seasonal vaccines,” says the study.