Recurrent apnoea post immunisation: Informing re-immunisation policy

BackgroundPreterm infants should receive immunisations according to their chronological, rather than gestational, age however concern about possible adverse events following immunisation (AEFI) in this group often means routine immunisations are delayed. A small number of infants may have apnoea with or without bradycardia temporally associated with immunisation. The risk factors for, and recurrence rate of apnoea with subsequent immunisations are unknown, which makes planning for subsequent immunisations for these highly vulnerable infants difficult.AimTo determine recurrence rates for apnoea temporally associated with immunisation in preterm and term infants and to explore potential risk factors associated with recurrent apnoea in preterm infants.MethodA retrospective analysis of all apnoea +/−bradycardia AEFIs in preterm and term infants, reported to the Surveillance of Adverse Events Following Vaccination In the Community (SAEFVIC), Victoria, Australia over a 3-year period from May 2007 to April 2010. Apnoea +/−bradycardia was defined as temporally associated with immunisation if it occurred up to 48 h after immunisation.Results7 out of 38 [18%, 95% confidence interval 6–31%] preterm infants with apnoea +/−bradycardia post initial immunisation had recurrent apnoea with subsequent immunisations. Possible risk factors for recurrence included: lower birth weight (p = 0.04) and ongoing hospitalisation for complications relating to prematurity (p = 0.01). No preterm infant with recurrent apnoea had a third episode of apnoea with subsequent immunisation. None of the 8 term infants with a reported apnoea AEFI had recurrence of apnoea with subsequent immunisation.ConclusionThere is a risk of recurrence of apnoea associated with immunisation in preterm infants. We recommend that preterm infants with apnoea post immunisation should receive reliable cardio-respiratory monitoring for a minimum of 24 h following the next scheduled immunisation.