Publication date: Jul 18, 2026
During the 2025-26 respiratory virus season, changes to COVID-19 vaccine eligibility, recommendations, and communication may have made vaccination follow-through especially challenging. Under-vaccination may reflect not only lack of willingness, but also breakdowns between willingness and uptake. We analyzed data from 3,390 adults in the CHASING COVID Cohort who completed assessments in August 2025 and March 2026 to examine gaps between vaccine willingness and subsequent influenza and COVID-19 vaccination. Vaccine willingness was defined using prior-season vaccination and stated intention to vaccinate during the 2025-26 respiratory virus season. In August 2025, 73% of participants were influenza vaccine willing and 68% were COVID-19 vaccine willing. Among vaccine-willing participants, 17% and 39% were unvaccinated for influenza and COVID-19, respectively, by March 2026. Absence of prior-season vaccination was the strongest predictor of not vaccinating for influenza and COVID-19, respectively (aRR [95% CI]: 4.04 [3.44-4.74]; 3.01 [2.72-3.34]). Non-vaccination was also associated with food insecurity (1.99 [1.66-2.37]; 1.47 [1.33-1.63]), any healthcare barrier (1.89 [1.57-2.28]; 1.51 [1.36-1.67]), and being not at all confident in vaccine safety (2.95 [2.15-4.05]; 2.21 [1.88-2.59]). Trajectory analyses suggested willingness-uptake gaps reflected incomplete follow-through on intentions and discontinuation among some prior vaccinators. Commonly reported reasons among vaccine-willing non-vaccinators included difficulty finding a convenient time, place, or appointment and, for COVID-19, lack of healthcare provider recommendation. Findings among non-vaccinated adults with prior or stated openness to vaccinate highlight missed opportunities and suggest avenues to improve coverage through strategies that reinforce vaccine confidence, reduce access and logistical barriers, and make vaccination easier to complete.
| Concepts | Keywords |
|---|---|
| Adults | |
| Covid | |
| Doi | |
| Https | |
| Influenza | |
| Medrxiv | |
| Org | |
| Participants | |
| Preprint | |
| Prior | |
| Season | |
| Uptake | |
| Vaccination | |
| Vaccine | |
| Willingness |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | Influenza |
| disease | MESH | COVID-19 |
| disease | MESH | included |
| disease | MESH | sph |
| disease | MESH | infection |
| disease | MESH | emergency |
| disease | MESH | chronic conditions |
| disease | MESH | emphysema |
| disease | MESH | chronic bronchitis |
| disease | MESH | coronary heart disease |
| disease | MESH | hypertension |
| disease | MESH | myocardial infarction |
| disease | MESH | asthma |
| pathway | KEGG | Asthma |
| disease | MESH | kidney disease |
| disease | MESH | AIDS |
| disease | MESH | plan |
| disease | MESH | allergy |
| disease | MESH | fatigue |
| disease | MESH | confusion |
| disease | MESH | Dis |
| drug | DRUGBANK | Nonoxynol-9 |
| disease | MESH | hhs |
| drug | DRUGBANK | Coenzyme M |
| disease | MESH | Autism |