First immunization of premature infants born before 33 weeks of gestation; safe at home or is cardiorespiratory monitoring in the hospital necessary?

Current guidelines advise to administer the first immunization to preterm
infants at the age of 2 months as protection against infectious diseases is
important for these vulnerable infants. However, it is uncertain whether
immunization at such a young postconceptional age is safe or not. Previous
studies indicate that these infants are at increased risk of post-immunization
cardiorespiratory disturbances. Therefore cardiorespiratory monitoring after
immunization may be necessary.
Extremely premature born infants usually still reside in the neonatal ward at
the age of 2 months, and consequently cardiorespiratory monitoring after the
first immunization can easily be applied. However, less extremely premature
born infants have often already left the hospital by the time they have to
receive their first immunization. In them, the need for cardiorespiratory
monitoring will lead to re-admission to the hospital. It is important to know
whether cardiorespiratory monitoring in these recently discharged ex-premature
children is really needed.

In a previous study we observed only benign cardiorespiratory events following
the first immunization in premature born infants who had already left the
hospital before the first immunization. This led us to conclude that
immunization without cardiorespiratory monitoring appears to be safe in these
infants. However, limitations of the first study were the limited sample size
and the lack of a control group. In order to provide stronger evidence for the
suggested strategy (immunization at home without cardiorespiratory monitoring)
we want to continue our research in a next study. In the proposed study we
focus on the causal relation between immunization and the observed
cardiorespiratory events

The purpose of this study is to determine whether the first immunization causes
cardiorespiratory events in premature born children that have already been
discharged from the hospital.

Prospective observational cohortstudy.

After informed consent of the parents is obtained, children are re-admitted to
the our hospital at the uncorrected age of 2 months the afternoon of the day
before the vaccination is given. On the day of admission the children are
cardiorespiratory monitoring starts. The vaccine is administered at 09.00hours
on day 2, and monitoring then continued for 24 hours. Immunization takes place
according to the rules of the national vaccination program. All patients
receive a pneumococcal conjugate vaccine (Synflorix) and a combination vaccine
for diphtheria (D), acellular pertussis (aP), Tetanus (T), Polio (P),
Haemophilus influenzae B (Hib) and Hepatitis B (infanrix hexa).
Disturbances in cardio-respiratory parameters will be described using a
standardized form. An apnea is defined as an isolated respiratory arrest of >=
20 seconds or an apnea of> 15 seconds with a heart rate <80 beats per minute
for 5 seconds (Stein Schneider). A bradycardia is defined as a heart rate <80
beats per min for >= 20 seconds. Finally, desaturation refers to a transcutanous
measured oxygen saturation <86% for > 15seconds. All these values will be noted
during an incident and regardless of that every three hours. Furthermore, if an
incident occurs the neonatal event registration will be printed out, so
sequence of events can be determined. Finally, every three hours adverse
reactions such as local skin reactions, temperature instability,
gastrointestinal complaints, sleep disturbances and need for analgesics are
noted following the standardised observation lists.

Extra burden consists of an extra night observation in the hospital (the night
before the immunization).
No increased risk.