Time lapses between distribution of influenza vaccines to health authorities and their administration by General Practitioners (GPs) to older adults: a retrospective study over five influenza seasons in Italy

ABSTRACT

Background

Delays in influenza vaccine delivery and administration can hinder vaccine coverage and protection. This study examines the differentials in distributing and administering adjuvanted trivalent (aTIV) and quadrivalent influenza vaccines (aQIV) to older adults in Italy’s primary care setting and its potential impact on hospitalization risk over 5 epidemic seasons.

Methods

Using a primary care database, individuals aged ≥ 65 years were selected. The proportion of vaccine distribution to regional authorities and subsequent administration by GPs was estimated using census data. Using quantile (median) regression, we examined the relationship between velocities of vaccine distribution and administration (doses/week) and the incidence of hospitalizations.

Results

Over the 5 influenza seasons, the velocity of distribution and administration of aTIV/aQIV ranged 341–833 and 152–270 median doses/week; no trend was yielded for the difference between these velocities (p = 0.189) or vaccine coverage (p = 0.142). An association was observed for each differential dose/week between distributed and administered vaccines and all-cause hospitalizations with a 10% increase in 2017–2018, 54% in 2018–2019, and 12% in 2020–2021 season.

Conclusions

These findings highlight the importance of minimizing the time lapse between vaccine distribution and administration to mitigate the impact of influenza and address factors that contribute to vaccination barriers.

KEYWORDS:

• Influenza vaccine
• older adults
• elderly
• influenza hospitalizations
• velocity
• distribution
• administration
• time lapse

Declaration of interest

F Lapi and E Marconi provided consultancies in protocol preparation for epidemiological studies and data analyses for Seqirus, GSK, Sanofi, Pfizer and MSD. A Rossi and C Cricelli provided clinical consultancies for Seqirus, GSK, Sanofi, Pfizer, and MSD. E Fallani, M Salvatore, and M Cambiaggi are full-time employees of Seqirus S.r.l. The present study was, however, conceived and carried out during the PhD program at University of Siena by E Fallani and M Salvatore, and outside working hours at Seqirus S.r.l. 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.

Reviewer disclosures

A reviewer on this manuscript has disclosed that they receive funding from an investigator initiated grant from Sanofi. Additionally, a reviewer on this manuscript has received honoraria for their review work. Peer reviewers on this manuscript have no other relevant financial or other relationships to disclose.

Acknowledgments

Medical consultant C. Gordon Beck and Amanda M. Justice provided editorial support in the preparation of this article, which was funded by CSL Seqirus.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/14760584.2023.2291184.

Additional information

Funding

This study was funded by Seqirus S.r.l., a pharmaceutical company that manufactures and commercializes influenza vaccines.