The burden of seasonal influenza: improving vaccination coverage to mitigate morbidity and its impact on healthcare systems

Dear Editor,

We read with interest the article by Oh K.B et al. (2022; Lifting non-pharmaceutical interventions following the COVID-19 pandemic – the quiet before the storm?) predicting an increase in vaccine-preventable diseases, such as influenza, after the relaxation of COVID-19 non-pharmacological interventions and recommending proactive interventional policies and a strong vaccination campaign to reduce the infection burden and mitigate the pressure on healthcare systems [1]. We fully agree with the authors and have some additional comments to put forward in this publication.

Recently, different authors hypothesized a declining influenza immunity in the population (due to the lower viral circulation in 2020 and 2021), and a higher burden during the upcoming influenza seasons [1–3], as happened in 2022 in the Southern Hemisphere. Along with estimating the intensity/seriousness of the upcoming season, historical epidemiological data showed us that it is even far more important to identify and implement the preventive measures that could limit any potential serious influenza outbreak not only this year but each year.

Seasonal influenza vaccination is the most effective method to prevent 1 out of 4 ICU admissions and 1 out of 3 deaths caused by influenza [4], and in children, vaccination was associated with 53% efficacy in reducing influenza-associated hospitalizations [5]. Other studies have found similar findings, showing that influenza vaccination reduces overall complications, ICU admission, and death [6]. COVID-19 has shown us how vaccination is even more important in case of a pandemic situation, to avoid the collapse of the public health systems. Recent studies have shown that coinfection of SARS-CoV-2 and influenza is a concern and is associated with a 6-fold increased odd of death and severe disease [7,8], further supporting the need for improved vaccination rates.

In our opinion, vaccination should not be limited only to younger children, children and adults with underlying medical conditions, and older adults; rather, it is a universal need, irrespective of age or comorbidities and WHO properly recommended annual influenza vaccination for all people over 6 months of age [9]. Considering the positive cost-effectiveness profile of influenza vaccines [9], an overall increase in vaccination rates among all the groups, at higher or at lower risk, would lead to the direct protection of vaccinated subjects, and substantial public health benefits, such as reducing transmissibility, mitigating the viral activity and the potentially increased population susceptibility. Children serve as major disseminators of the virus during influenza outbreaks. Hence, vaccinating children of all age groups, including those at lower risk, will significantly reduce the influenza burden and its management costs, along with protecting vulnerable household contacts. Universalization of the influenza vaccine may increase healthcare budgets in the short term; however, in the long term, it helps to reduce healthcare budgets by reducing the number of hospitalizations and medical expenses associated with influenza-related complications. Additionally, preventing the influenza through vaccination can lead to increased productivity and reduced absenteeism in the workforce, which can have economic benefits.

Despite all these known benefits, the influenza vaccination rate in the EU is below the target of 75%, with some countries having alarming coverage rates of <20%. Considering the documented annual burden of flu-associated disease and its complications, insufficient immunization rates may vanish the efficacy of the preventive action represented by the vaccination itself and result in avoidable infections and hospitalizations, with severe public health impact and more pressure on the overstretched health systems. Hence, improving the vaccination rates and reaching the target vaccination coverage is a compelling need that could be addressed with a strong vaccination campaign and clear communication to and by healthcare professionals (HCPs), institutions, and the population, about the motivation enhancement as well as the personal and community benefits of influenza vaccination.

Different influenza vaccines are currently available on the market (standard-dose, high-dose, adjuvanted, egg-based, cell-based, recombinant), and policymakers and payers face a delicate task in providing influenza immunization guidelines and recommendations. Recent meta-analyses showed minimal differences in the efficacy and safety profiles of different types of vaccines [10] and it is important to bear in mind that the vaccination with any vaccine has unsurpassed clinical and health-economic benefits compared with the non-vaccination option [9].

Considering there is a huge number of people requiring vaccination, we recommend maintaining broader access to all the marketed vaccines, in line with their approved labels (i.e. age groups, specific sub-groups, contraindications) to facilitate the increase in vaccine coverage: in fact, the benefits of an increased overall vaccine coverage surpass the differences in effectiveness rates between the different vaccines types [11] and keeping broad access to all the approved vaccines can maximize the vaccination benefits and limit the excess of public health expenditure.

Increased vaccine coverage can be achieved through proper education of all relevant stakeholders such as policymakers, payers, population, and HCPs – regarding the annual burden of influenza-associated disease and the benefits of preventing influenza by vaccination, and by maintaining broad access to all the available vaccines. Policymakers should seriously consider the recent data highlighting an impactful upcoming influenza seasons and focus on improving access to vaccination and increasing the vaccine coverage rates in the overall population.

Declaration of competing interests

J Schelling received financial grants from Pfizer, worked as a consultant and delivered talks for Viatris, GSK, MSD, Sanofi, Pfizer, BioNTech, Seqirus and Janssen pharmaceuticals. Y Zöllner worked as a consultant for Viatris, Menarini and Teva and has been an instructor for CME/CPE-accredited modules (contracted by German affiliate of Menarini). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or material discussed in the manuscript apart from those disclosed.

Author contributions

All authors contributed equally in conceptualization, supervision, writing – the original draft, and review & editing. All authors agree to submit the manuscript for publication in ‘Expert Review of Vaccines’.

Additional information

Funding

This paper was not funded.