Vulnerable Infants With Chronic Lung Disease Show Unequal Immunization Rates, Study Finds

Infants and young children with bronchopulmonary dysplasia, a chronic lung disease that follows premature birth, are among the most medically fragile patients in pediatrics. Their damaged lungs leave them acutely vulnerable to respiratory viruses that most children shrug off, and their care often involves months of hospitalization, home oxygen, and careful monitoring long after discharge from the neonatal intensive care unit. A new retrospective cohort study published in BMC Pediatrics now adds a troubling dimension to this picture: immunization rates against influenza and respiratory syncytial virus, the two pathogens that pose the greatest seasonal threat to these children, vary by race and ethnicity in ways that researchers say demand closer attention from clinicians and health systems alike.

The study, led by Mallory Go of the Department of Epidemiology at Brown University School of Public Health together with colleagues at Yale, Nationwide Children’s Hospital, Johns Hopkins, and The Miriam Hospital, drew on the multicenter registry of the BPD Collaborative, a network of centers that tracks outcomes for children with the disease. The analysis included 1,185 patients with bronchopulmonary dysplasia, making it one of the larger efforts to examine immunization patterns specifically within this high-risk population. Because the children were drawn from multiple centers across the United States, the findings are less likely to reflect the quirks of any single institution and more likely to capture a systemic pattern.

Bronchopulmonary dysplasia is the second most common chronic lung disease of childhood, and its burden falls disproportionately on infants born extremely prematurely, whose lungs are still developing when they are thrust into the world and onto ventilators. Children with the condition use more health care than their peers without it, and respiratory infections hit them hardest. Respiratory syncytial virus, in particular, is a leading cause of rehospitalization in this group, and influenza can trigger severe exacerbations that require oxygen escalation, systemic steroids, and sometimes intensive care. Immunization is therefore one of the most straightforward protective measures available, which is precisely why gaps in coverage matter so much.

To probe those gaps, the research team used mixed-effects multinomial logistic regression to compare the relative probability of being fully immunized, partially immunized, or unimmunized against influenza across racial and ethnic groups, with non-Hispanic Black patients as the reference category. The multinomial framework matters technically: rather than collapsing immunization into a simple yes-or-no outcome, it allows the researchers to model the risk of landing in each distinct category, which is essential when partial immunization may carry its own clinical significance. Mixed-effects models, meanwhile, account for the clustering of patients within centers, preventing the characteristics of any one hospital from distorting the pooled estimates.

The headline finding was unexpected in its direction. Non-Hispanic white patients had a higher relative risk of being unimmunized, rather than fully immunized, against influenza compared with non-Hispanic Black patients, with a relative risk ratio of 1.10 and a 95 percent confidence interval of 1.01 to 1.20. The effect size is modest, and the confidence interval sits close to the null value of one, which counsels caution in interpretation. Still, the result challenges a common assumption in disparities research that minority children consistently face lower immunization rates, and it suggests that within this particular clinical population, the barriers to full influenza vaccination may cut across groups in ways that standard frameworks do not predict.

The second strand of the analysis shifted from who gets vaccinated to what happens when vaccination is incomplete. Using mixed-effects logistic regression, the team examined the association between immunization status and adverse respiratory outcomes after discharge. Partially immunized patients had roughly twice the odds of requiring post-discharge rescue medication use compared with fully immunized patients for influenza, with an adjusted odds ratio of 2.02 and a 95 percent confidence interval of 1.47 to 2.76. For respiratory syncytial virus, the corresponding adjusted odds ratio was 1.66, with a confidence interval of 1.16 to 2.37. Rescue medications, which include inhaled bronchodilators and other agents used to manage acute respiratory symptoms at home, are a meaningful marker of disease exacerbation in this population.

The pattern held for systemic corticosteroid use, a more intensive marker of acute illness. Partially immunized patients had higher odds of receiving systemic steroids for acute symptoms compared with fully immunized patients, with an adjusted odds ratio of 2.03 for influenza and 1.68 for respiratory syncytial virus, and confidence intervals that excluded the null value in both cases. Taken together, these results suggest that the distinction between full and partial immunization is not merely administrative. Children who received some but not all recommended doses fared measurably worse, a finding that carries practical weight for clinicians deciding how hard to push families toward completing multi-dose schedules.

Several caveats temper the conclusions. As a retrospective cohort study, the analysis can identify associations but cannot prove that incomplete immunization caused the worse outcomes; unmeasured differences in illness severity, access to care, or family circumstances could influence both vaccination status and respiratory outcomes. The modest and near-null disparity estimate for influenza immunization likewise warrants replication before firm conclusions are drawn about which groups are most affected. The authors also note that social determinants of health, the economic and social conditions that shape health care access, were part of the study’s conceptual framing, and that a directed acyclic graph was used to guide the modeling choices, reflecting an effort to be explicit about confounding.

The study’s institutional scaffolding speaks to its credibility. It was conducted in accordance with the Declaration of Helsinki, with caregiver informed consent obtained under institutional review board approved protocols, and the Brown University Health Institutional Review Board determined that the secondary analysis qualified as non-human subject research. The work was partially supported by the Brown University Nora Kahn Piore Award and the Hassenfeld Child Health Innovation Institute, and the authors declared no competing interests. The paper was received in June 2026, accepted in October, and published on October 13, 2026, as an open access article under a Creative Commons license.

What the study ultimately offers is a call to look more carefully at a population that too often falls between the cracks of pediatric immunization campaigns. Children with bronchopulmonary dysplasia stand to benefit enormously from complete protection against influenza and respiratory syncytial virus, and the finding that partial immunization is associated with doubled odds of rescue medication use gives clinicians a concrete, actionable target: completion, not just initiation, of vaccination series. The racial and ethnic patterns observed, including the higher likelihood of remaining unimmunized among non-Hispanic white children, complicate simplistic narratives and underscore the need for center-level data, family engagement, and follow-up systems that reach every child with chronic lung disease, regardless of background. As the BPD Collaborative registry continues to grow, future analyses may clarify the mechanisms behind these patterns and point toward interventions that close the gaps this study has begun to map.

Subject of Research: Racial and ethnic disparities in influenza and RSV immunization rates among infants with bronchopulmonary dysplasia

Article Title: Racial and ethnic disparities in immunization rates among infants with bronchopulmonary dysplasia: a retrospective cohort study

Article References: Racial and ethnic disparities in immunization rates among infants with bronchopulmonary dysplasia: a retrospective cohort study. (n.d.). https://doi.org/10.1186/s12887-026-07841-z

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07841-z

Keywords: bronchopulmonary dysplasia, immunization, racial disparities, influenza, respiratory syncytial virus, pediatrics, retrospective cohort study, premature infants, chronic lung disease, health equity, rescue medication, BPD Collaborative