MF59-adjuvanted vaccine: a safe and useful tool to enhance and broaden protection against seasonal influenza viruses in subjects at risk

Importance of the field: Vaccination is universally considered as the most effective tool for the prevention of influenza, which represents a significant burden, both from a health-care and a socio-economic viewpoint. Conventional non-adjuvanted vaccines have shown suboptimal immunogenicity in the elderly, in patients with serious chronic diseases or the immunocompromised and in young children. The protection offered by non-adjuvanted vaccines may be further reduced by periodic antigenic drifts. Areas covered in this review: Between the several strategies proposed to address the need for more immunogenic vaccines than the conventional ones, the most successful strategy is represented by the use of adjuvants. Since 1997, an MF59-adjuvanted subunit influenza vaccine has been licensed in several countries and used in the elderly worldwide. Available data on the safety, immunogenicity and effectiveness of this vaccine have been reported and discussed in details. What the reader will gain: The MF59-adjuvanted vaccine has been shown to enhance immunogenicity and to confer cross-reactivity against heterologous influenza viral strains in the elderly, in adults with serious underlying medical conditions and in healthy infants and young children. Furthermore, its effectiveness has been demonstrated in older adults, reducing hospitalizations for pneumonia, cardiovascular and cerebrovascular diseases. Take home message: The vaccine is safe, with an acceptable tolerability profile, thus representing a valid option to optimize the control of seasonal influenza.