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Apnoea after the 2-month immunisation in extremely preterm infants: What happens with the 4-month immunisation?


  • Conflict of interest: None declared.

Correspondence: Dr Scott A Morris, Centre for Perinatal Medicine, Flinders Medical Centre, Bedford Park, Adelaide, SA 5042, Australia. Fax: 618 82043143; email:



To describe the outcome of the 4-month immunisation in a cohort of extremely preterm babies who had clinically significant apnoea after their 2-month immunisation.


A retrospective audit was conducted from January 2001 to January 2011 at Flinders Medical Centre (FMC). Suspected apnoeic reactions to the 2-month immunisation in preterm infants ≤28 weeks + 6 days gestation were identified from the Neonatal Unit database. The medical records of babies with reactions then reviewed. We classified apnoeic reactions using predefined criteria into likely, possible or unlikely. The outcomes for subsequent immunisations were determined either when babies were specifically readmitted to FMC for immunisation and cardiorespiratory monitoring, or from the SA Health Immunisation Unit database.


There were 203 extremely preterm babies at FMC over the study period who received their 2-month immunisation as inpatients. Clinically significant apnoea post immunisation occurred in 17 (8.4%) babies (likely in 12 and possible 5). The subsequent (4-month) immunisation was given with inpatient cardiorespiratory monitoring in nine babies (seven with likely and two with possible reactions), and no instability was identified. There were eight babies not readmitted to FMC for the subsequent immunisation. No reported adverse events were recorded on the SA Health Immunisation Unit database for these babies.


Apnoea following the 2-month immunisation in extremely preterm infants is not likely to be repeated with the subsequent immunisation. Prospective surveillance using standardised case definitions and monitoring protocols in this population are required to guide uniform practice.