High-Dose Influenza Vaccine Highly Effective in Preventing Hospitalizations: Study

A new study discovered that the high-dose quadrivalent influenza vaccine (QIV-HD) outperforms the standard-dose version (QIV-SD) in preventing recurrent hospitalizations among older adults of 65 to 79 years. The findings were published in the Clinical Microbiology and Infection.

This post-hoc analysis of an open-label, randomized trial enrolled a total of 12,477 participants from October to November of 2021 and followed them until May 31, 2022. The participants were randomly assigned to receive either QIV-HD or QIV-SD. The outcomes were monitored 14 days after vaccination and focused on various outcomes, including hospitalizations for pneumonia or influenza, respiratory and cardio-respiratory hospitalizations, cardiovascular hospitalizations, all-cause hospitalizations and all-cause mortality. 

The results from this study revealed a significant association between QIV-HD and lower incidence rates of hospitalizations for pneumonia or influenza (10 vs. 33 events) and all-cause hospitalizations (647 vs. 742 events) when compared to QIV-SD. Also, the benefits of QIV-HD were consistently observed over time even before the onset of active influenza transmission.

The data showed that the first significant reduction in hospitalizations for pneumonia or influenza occurred by calendar week 3 of 2022, while the influenza test positivity rate reached over 10% only in calendar week 10 of 2022. This indicates that the effectiveness of QIV-HD extends beyond the active influenza circulation which suggests a broader protective effect. This post-hoc analysis indicates that QIV-HD may offer a more active defense against recurrent hospitalizations than QIV-SD, with trends favoring the high-dose vaccine evident independently of influenza circulation levels.

Source:

Johansen, N. D., Modin, D., Skaarup, K. G., Nealon, J., Samson, S., Dufournet, M., Loiacono, M. M., Harris, R. C., Larsen, C. S., Reimer Jensen, A. M., Landler, N. E., Claggett, B. L., Solomon, P. S. D., Landray, P. M. J., Gislason, P. G. H., Køber, P. L., Stæhr Jensen, P. J. U., Sivapalan, P., Vestergaard, L. S., … Biering-Sørensen, P. T. (2024). Effectiveness of high-dose vs. standard-dose quadrivalent influenza vaccine against recurrent hospitalisations and mortality in relation to influenza circulation: a post-hoc analysis of the DANFLU-1 randomised clinical trial. In Clinical Microbiology and Infection. Elsevier BV. https://doi.org/10.1016/j.cmi.2024.01.017