Influenza Vaccination is More Effective in Individuals Vaccinated Against Pneumococcus

Influenza vaccines administered in the 2023-2024 season reduced the risk of death and hospitalisation caused by influenza and pneumonia among the elderly by almost 50%. But the effectiveness exceeded 80% in individuals who had also been vaccinated against pneumococcus or Covid-19, as revealed by a study published in the journal Vaccines. Lamberto Manzoli, epidemiologist and professor at the Department of Medical and Surgical Sciences of the University of Bologna, led the study.

The research—also involving researchers from the University of Ferrara and the Pescara Local Health Authority (ASL Pescara)—is the first in the world to compare the effectiveness of all influenza vaccines and the co-administration of additional vaccinations.

The researchers monitored the elderly population of the province of Pescara for eleven months, from October 2023 to September 2024. All official data were collected, the follow-up covered the full season, and the analyses were adjusted according to multiple factors, including the participants’ age, sex, and clinical risk.

The results showed that, among those vaccinated against influenza, both the risk of death and hospitalisation caused by pneumonia or influenza were reduced by about 50% compared to those not vaccinated. The effectiveness was similar regardless of age and sex. However, the risk was significantly lower for those who had also received other vaccinations.

“The data we analysed revealed a particularly significant finding regarding individuals who had received the pneumococcal vaccine or the Covid-19 vaccine”, says Lamberto Manzoli. “The effectiveness of multiple vaccinations was very high, even exceeding 80%”.

The analysis also compared the effectiveness of the different seasonal vaccines, finding no substantial difference between adjuvanted vaccines, designed to provide a stronger and longer-lasting antibody response, and non-adjuvanted ones. In addition, standard-dose vaccines showed similar results to the most recent formulation, which contained a higher dose of antigen.

“This analysis of our population provides direct and concrete evidence supporting current vaccination recommendations”, says Dr Graziella Soldato, head of the vaccination programmes at ASL Pescara. “Immunisation remains a key tool for public health, especially among the most vulnerable groups”.

The study was published in the journal Vaccines with the title “The Effectiveness of Four Quadrivalent, Inactivated Influenza Vaccines Administered Alone or in Combination with Pneumococcal and/or Sars-Cov-2 Vaccines: A Population-Wide Cohort Study”. Lamberto Manzoli, professor at the Department of Medical and Surgical Sciences of the University of Bologna, coordinated the survey. Cecilia Acuti Martellucci, Alessandro Bianconi, and Matteo Fiore of the University of Bologna; Maria Elena Flacco, Annalisa Rosso, and Enrico Zauli of the University of Ferrara, together with Graziella Soldato, Patrizia Marani Toro, Marco De Benedictis, Graziano Di Marco, Roberto Carota, and Rossano Di Luzio of ASL Pescara, were among the participants.