Association between combination COVID-19-influenza vaccination and long COVID in middle-aged and older Europeans: A cross-sectional study

ABSTRACT

The potential impact of combined COVID-19 and influenza vaccination on long COVID remains uncertain. In the present cross-sectional study, we aimed to investigate the plausible association between them in middle-aged and older Europeans based on the Survey of Health, Ageing, and Retirement in Europe (SHARE). A total of 1910 participants were recruited in the analyses. The study outcome was long COVID. Participants were divided into 4 groups through the self-reported status of COVID-19 and influenza vaccination. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. 1397 participants experienced long COVID. After multivariable adjustment, those vaccinated with neither COVID-19 nor influenza vaccine had higher risk of long COVID (OR, 1.72; 95% CI, 1.26–2.35) compared to those vaccinated with both vaccines. Furthermore, adding the 4 statuses of COVID-19 vaccination/influenza vaccination to conventional risk model improved risk reclassification for long COVID (continuous net reclassification improvement was 16.26% [p = .003], and integrated discrimination improvement was 0.51% [p = .005]). No heterogeneity was found in the subgroup analyses (all p-interaction ≥0.05). Our study might provide a strategy for people aged 50 and over to reduce the occurrence of long COVID, that is, to combine the use of the COVID-19 vaccine and influenza vaccines.

KEYWORDS:

• COVID-19 vaccine
• influenza vaccine
• combined use
• long COVID
• Survey of Health, Ageing, and Retirement in Europe

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical statement

The study adhered to the ethical principles outlined in the World Medical Declaration of Helsinki and received approval from the University of Valencia’s Ethics Committee for Human Research (register code 1510464).

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2345505

Additional information

Funding

This work was supported by Wuxi Development Discipline Construction Project [NO. FZXK2021010].