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Immunization of Preterm and
Low Birth Weight Infants
Marietta Vázquez, MD, FAAP
Yale University School of Medicine
• No conflict of interest
Immunization of Preterm and Low Birth
Weight Infants
• The development of a safe and effective childhood immunization
schedule has effectively reduced morbidity and mortality from
vaccine-preventable diseases worldwide.
• Studies demonstrate that vaccines are SAFE in preterm and low
birth weight infants. [pre-term--gestational age <37 weeks; low
birthweight as <2,500 g ]
• Vaccine Safety--Immunization in these infants is safe and effective.
However, post-vaccination apnea with or without associated
bradycardia up to 48 hours post-immunization may be increased in
some groups.
Vaccine Safety
Apnea and Premies After Immunization
Factors possibly associated with an increased incidence of postimmunization apnea
•Apnea within the 24 hour period before immunization
• More severe illness at birth
• Chronological age less than 67 days and/or earlier gestational age in infants with a
birth weight of less than 1500g
• An apneic episode following the first immunization event
• No long term sequelae have been associated with post immunization apneic
events.
• Immunization should not be withheld or delayed.
Immunization of Preterm and Low Birth Weight Infants
Vaccine Immunogenicity
• Studies demonstrate that vaccines are IMMUNOGENIC in preterm
infants.
• Vaccine immunogenicity --Although the magnitude of immune
responses may sometimes be lower for specific vaccines in preterm
infants, protective and durable responses are achieved in most cases.
Evidence suggests their response is still protective.
Immunization of Preterm and Low Birth
Weight Infants
• Preterm infants are at increased risk of experiencing complications
of vaccine-preventable diseases, which are particularly severe in
young infants, especially those born preterm (gestational age <37
weeks) or low birthweight (<2,500 g) infants.
• The increased risk from infections is mainly because immune
defenses are functionally impaired in early life.
• The seriousness of the infectious problems of premature infants is
proportional to how premature they are, but irrespective of this, they
are more serious than those of full-term infants because their
immune system is compromised to a greater extent.
Passive Immunity in Preterm Infants
• Transplacental transfer of maternal immunoglobulin G (IgG) that can
protect an infant against some vaccine preventable diseases is
affected by a range of factors including the mother’s past exposure to
the disease and vaccination history, antibody half-life and the infant’s
gestational age.
• Infants born at less than 32 weeks gestation have significantly less
IgG compared with those born at 32-36 weeks. Furthermore, IgG
wanes more rapidly rendering preterm infants at increased and
earlier risk for vaccine preventable diseases
Immunization of Preterm and Low Birth
Weight Infants
• Larger premature infants mount immune responses to vaccines similar to
those of full-term infants, but very premature infants (<28-32 weeks'
gestation at birth) may have specific defects in vaccine responsiveness.
• Although there are minor differences in immunogenicity, the immune
responses to diphtheria, tetanus, pertussis, and polio antigens are similar
between full-term and premature infants.
• Few data on influenza vaccine in premature infants are available, but
infants with pulmonary disease may respond less robustly than others.
• Some studies have shown that premature infants seem to have lower
antibody responses to vaccines than full-term infants; however, vaccine
efficacy in premature infants remains high.
Immunization of Preterm and Low Birth Weight Infants
Diphtheria, Tetanus, Pertussis, H flu and Polio
• Several studies conducted in the past decade have confirmed
previous findings of acceptable safety, immunogenicity, and efficacy
of DTaP, diphtheria and tetanus toxoids and whole-cell pertussis
(DTaP), Hib, oral poliovirus (OPV), and IPV vaccines in preterm infants
(including those of ELBW) beginning at a chronologic age of 2 months.
• The safety of DTaP, Hib, and IPV vaccines given to PT and LBW infants
is comparable to that in FT infants, with no increase in vaccine
adverse events noted
Immunization of Preterm and Low Birth Weight Infants
Pneumococcal conjugate vaccine
• Pneumococcal conjugate vaccine is efficacious in premature infants.
• Nearly 38,000 infants participated in clinical trials using PCV7, many of
whom were preterm and low birth weight. After the initial 3 doses of PCV7,
PT infants demonstrated immune responses to all 7 pneumococcal
serotype components of PCV7 that were equivalent to those found in FT
infants. None of the PT and LBW infants receiving PCV7 in the trial
contracted invasive pneumococcal disease attributable to vaccine
serotypes.
• The safety and immunogenicity PCV13 were shown to be non-inferior to
that of Prevenar® in full term healthy infants and toddlers, a condition of
licensure. Equivalent safety, tolerability and immunogenicity profiles of
PCV13 in preterm and/or low birth weight infants can be inferred from the
profile for Prevenar®
Immunization of Preterm and Low Birth Weight Infants
Hepatitis B vaccine
Premature infants of mothers who are hepatitis B surface antigen
(HBsAg) negative
• The response to hepatitis B (HB) vaccine may be diminished in
premature infants with birth weight less than 2,000 grams.
• In jurisdictions where the 1st dose of HB vaccine is routinely given at
birth, routine HB immunization of infants should be delayed until the
infant reaches 2,000 grams or upon hospital discharge if discharge
occurs before the infant has reached 2,000 grams.
http://www.cdc.gov/hepatitis/hbv/pdfs/correctedtable4.pdf
Immunization of Preterm and Low Birth Weight Infants
Influenza Vaccine
• As with all children, PT and LBW infants are at increased risk of excess
morbidity from influenza virus infections.
• Few data on influenza vaccine in premature infants are available, but
infants with pulmonary disease may respond less robustly than
others.
• Although cell-mediated responses often were depressed in PT infants
with more advanced CLD, nearly all PT infants, regardless of their
health status and previous influenza immunization history, were able
to achieve and sustain protective concentrations of antibody to the 3
strains of influenza virus contained in influenza vaccine.
Outside of the US
Bacille Calmette Guérin vaccine
• Bacille Calmette Guérin vaccine appears to be most immunogenic if
delayed until at least 34-35 weeks' postmenstrual age in very
premature infants, although there may be non-specific advantages to
its earlier administration.
Immunization of Preterm and Low Birth
Weight Infants
• Preterm infants are also less likely to receive immunizations on time.
• Premature infants are not adequately immunized because of fear of
adverse reactions and poor antibody response to the immunizations, lack
of adequate muscle mass for the injections, or the premature infant simply
being "too small" or "too sick" to immunize.
• Despite established recommendations that preterm infants be immunized
on the same schedule as term infants, with a few exceptions for specific
vaccines, considerable immunization delays are reported.
• Do not adjust age for preterm birth
• Neonatal intensive care units and other hospital areas where premature
infants may remain hospitalized for prolonged periods should have
immunization programs in place.
Immunization of Preterm and Low Birth
Weight Infants
• Premature infants are at significant risk for decisions from healthcare
providers that delay beginning and completing their vaccine regimens. A
major challenge facing those who care for these infants is the provision of
timely immunization.
• Overall, the data indicate that premature infants should follow the same
vaccination schedule as that generally used for full-term infants, without
correcting for prematurity and regardless of birth weight.
• Vaccination of very-low-birth-weight infants in the US and elsewhere is
significantly delayed, especially in infants with a birth-weight of < 1000 g
and lower gestational age.
• Urgent educational interventions targeting physicians and nurses should
be implemented in order to improve vaccination rates and timing in these
high risk populations.
SUMMARY
Timing
• Medically stable PT and LBW infants should receive all routinely
recommended childhood vaccines at the same chronologic age as
recommended for FT infants. Under most circumstances, gestational age at
birth and birth weight should not be limiting factors when deciding whether a
PT or LBW infant is to be immunized on schedule. Infants with birth weight
less than 2000 g, however, may require modification of the timing of hepatitis
B immunoprophylaxis depending on maternal HBsAg status.
Dosing
• Vaccine dosages normally given to FT infants should not be reduced or divided
when given to PT and LBW infants.
OTHER STRATEGIES…. What else can we do?
• For other vaccine-preventable diseases that specifically target (eg,
group B Streptococcus) or are particularly severe (eg, pertussis) in
preterm and term infants or for which no vaccine is licensed in this
age group (eg, influenza), other immunization strategies such as
maternal immunization or targeted immunization may reduce
morbidity and mortality.
Cocoon Strategy and
The Newborn
What Does it Mean to Cocoon a Newborn?
• I urge parents to cocoon their babies; that is, provide a family of
surrounding protection by having every single child and adult
immunized against whooping cough, influenza, and other vaccinepreventable illnesses.
• By surrounding a baby with only immunized people, you cocoon the
baby against serious infections.
The Importance of Cocconing
• Whooping cough is a highly infectious respiratory illness spread by
sneezing and coughing that can be deadly to young infants. Getting
a tetanus, diphtheria, acellular pertussis (Tdap) shot is the best way to
avoid getting whooping cough.
• Amid an epidemic, we worry most about newborns because they are
most vulnerable to complications and lack vaccine protection.
• If every child and adult who surrounds a newborn gets a Tdap shot,
the likelihood of the baby getting whooping cough approaches zero.
• Most newborns get whooping cough from their family or adults
around them.
summary
• If preterm babies get the infections that vaccines can prevent, they
have a greater chance of having disease-related problems.
• All of the available vaccines are safe when given to preterm and low
birth weight babies.
• Any side effects associated with the vaccines are similar in both fullterm and preterm babies.
• Immunization of Preterm and Low Birth Weight Infants, Thomas N.
SaariPediatrics 2003;112;193