Cardiorespiratory Adverse Events after First Vaccination in Preterm Neonates With Gestational Age ≤30 Weeks.

Objective: To document the adverse cardiorespiratory events following first routine immunization in preterm neonates.

Methods: We retrieved records of neonates with gestational age ≤30 weeks, and included those who developed cardiorespiratory events after first vaccines before discharge. Our Unit's protocol is to administer Bacillus Calmette-Guerin (BCG), hepatitis B vaccine to those discharged at <8 weeks postnatal age. Hexavalent, BCG, pneumococcal vaccine and rotavirus vaccines are given at 8 weeks of age, if hospital stay is predicted to be longer. Unit compliance to vaccination administration at appropriate ages were also measured.

Results: Data of 161 neonates ≤30 weeks (17.4% <27 week) who completed care in the unit was studied. Cardio-respiratory adverse events were reported in 21(13.7%). None of these required initiation of invasive ventilation. High flow nasal cannula therapy and caffeine restart were required for these events in 14 (9.3%) and 6 (3.9%) neonates, respectively. Lower gestational age, bronchopulmonary dysplasia and sepsis were significant risk factors on univariate analysis. On multivariate analysis, continued need for respiratory support at 4 weeks of age (P=aOR 14.5 (95% CI 5-59.1) was the only independent risk factor for post-vaccination cardiorespiratory adverse events. Of 38 who were not vaccinated at recommended ages by unit policy, 25 were missed opportunities, the rest were deemed unstable for vaccinations at that age by the clinical team.

Conclusion: Adverse cardiorespiratory events were uncommon after first vaccinations in very preterm neonates. Administering vaccines in this group before discharge would allow monitoring for these events, especially for those who require long-term respiratory support.