Clinical

Hexavalent vaccine induces immune response in preterm infants

Last Updated: 2005-12-09 10:19:49 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Preterm infants immunized with a hexavalent vaccine against childhood diseases show a good immune response to all six antigens, researchers in Spain report.

It is common for immunizations for preterm infants to be delayed, putting them at increased risk when they are the most vulnerable, Dr. Pilar Garcia-Corbeira, from GlaxoSmithKline in Madrid, and co-authors note in their report, published in the December issue of Pediatrics.

And while the safety and immunogenicity of the diphtheria-tetanus-acellular pertussis-hepatitis B virus-inactivated polio and Haemophilus influenzae type b (DTPa-HBV-IPV/Hib) vaccine has been demonstrated in full-term infants, similar experience is lacking in preterm infants.

Dr. Garcia-Corbeira's group therefore conducted a comparative study of 93 preterm infants and 89 full-term infants. All infants were vaccinated with the hexavalent vaccine at 2, 4, and 6 month of age.

Preterm infants showed a good immune response to all antigens, the authors report, even though geometric mean titers of antibodies tended to be lower than those of term infants.

Specifically, all the infants had seropositive anti-diphtheria, anti-tetanus, and anti-polio types 1, 2, and 3 antibody levels. All but six of those born preterm had seroprotective titers of anti-HbsAg antibodies, and six failed to respond to the HBV antigen.

Because pertussis is a major threat for premature infants, it is important to note that vaccine response rates to the three pertussis antigens were at least 98.9% in all of the infants, the authors indicate.

The investigators observed that the vaccine was well tolerated. Thirteen infants who had a gestational age of less than 28 weeks and a birth weight of no more than 1,000 grams had transient bradycardia and desaturation episodes within the 72 hours after the first immunization, but there were "no clinical repercussions," the authors add.

"New studies are certainly needed to evaluate DTPa-HBV-IPV/Hib immunogenicity in preterm infants using different schedules, but at least this vaccine given at 2, 4, and 6 months can greatly facilitate the compliance with vaccination programs in premature newborns," they conclude.

Pediatrics 2005;116:1292-1298.