Improving detection of secondary immunodeficiency and vaccination after invasive airway infections: a prospective cohort study with retrospective comparison
B. Tan, M. Metlapalli, M. Liu, D. Kotsanas, E. L. Smith, S. OjaimiAbstract
Background
Infections caused by encapsulated pathogens such as Streptococcus pneumoniae , Haemophilus influenzae and Neisseria meningitidis contribute to significant morbidity and mortality, with immunodeficiency being an important risk factor for recurrent and invasive disease. A previous retrospective Australian study identified a 6% rate of newly diagnosed immunodeficiency in such patients and highlighted inadequate screening.
Methods
A prospective study at a large multi‐centre health service in South‐East Melbourne, Australia was conducted between June 2021 and September 2023. Adults (≥16 years) with the aforementioned organisms, isolated from sterile sites, were recruited. Participants underwent basic immunodeficiency testing and vaccinations. A retrospective cohort, comprising eligible but unenrolled patients over the same period, was retrospectively analysed for comparison.
Results
Patients within the prospective cohort ( n = 46) were compared with the retrospective cohort ( n = 69), with the predominant organisms being S. pneumoniae (83%, 94/115), H. influenzae (13%, 15/115) and N. meningitidis (4%, 5/115). Vaccine‐preventable strains accounted for 75% (55/73) of typed cases. A new diagnosis of immunodeficiency was identified more frequently in the prospective group (7/46, 15.2% vs 4/69, 5.8%, P = 0.1), with a numerically greater, though not statistically significant, increase in immunodeficiency detection rate seen in the prospective cohort (OR 2.9, 95% CI 0.7–14.3, P = 0.1). Post‐illness vaccinations were more frequently recommended in the prospective group (OR 2.6, 95% CI 1.0–64, P = 0.03).
Conclusion
Actively identifying patients with invasive airway pathogens and ensuring linkage with an infectious diseases service improves screening and diagnosis of immunodeficiencies and optimises vaccination opportunities.