Resposta imune à vacinação contra hepatite B em recém-nascidos pré-termo, iniciada no primeiro dia de vida

Abstract

Objective: To investigate the immune response of preterm infants to hepatitis B vaccination.Methods: Three doses of recombinant hepatitis B vaccine (5 µg dose) were administered to 35 preterm and 21 full-term infants within 24 hours after birth and at one and six months of postnatal age.Results: A protective antibody response (anti-HB > 10 mUI/mL) was observed three months after the last dose in 92.6% and 100% of preterm and full-term infants (p > 0.05), respectively. Newborns with gestational age below 34 weeks presented lower antibody responses in all three periods. However, gestational age was not important to determine the antibody response in the three periods analyzed. When antibody response was analyzed in terms of birth weight, it was observed that a protective response was present in 75 and 100% of newborns with birth weight < 1,500 g and > 1,500 g, respectively. Birth weight was shown to be a relevant factor in determining a protective antibody response at six months of postnatal age. Nonresponders received a fourth vaccine dose and an adequate antibody response was obtained in 100%. Conclusion:The antibody response of preterm infants was similar to that of term newborns. Hepatitis B vaccination can be initiated on the first day of life in preterm newborns, following the same scheme recommended for term newborns. However, in preterm infants with birth weight less than or equal to 1,500 g, whose antibody response is lower, anti-HB titers should be monitored at nine months of age, or a four-dose vaccination scheme should be provided, with doses on the first day of postnatal life and one, six and nine months later.

Prevenção das hepatites virais através de imunização

“…6,54 In premature newborns, weighing less than 2 kg, the antibody levels are lower and the seroconversion rates smaller. A recent study conducted by Sadeck & Ramos, 56 about response to vaccination in pre-term newborns, showed a similar response to that in full term babies. However, in 25% of those with birthweight equal to or lower than 1,500 g, the response was not satisfactory.…”

“…The authors indicated the need to assess seroprotection after the third dose of the vaccine or administer 1 booster dose at 12 months. 56 Among adolescents and adults, the antibody response rates are 20% to 30% after one dose, 75% to 80%…”

Active and passive immunization in the extremely preterm infant

“…Crianças com peso ao nascer acima de 2 kg respondem de forma semelhante às de termo e de peso adequado 7,43 . A vacinação a partir de 1 mês de idade já apresenta resposta adequada, independendo do peso de nascimento, o que autoriza o início da vacinação aos 2 meses de idade, com qualquer peso, e a partir de 1 mês de idade em prematuros clinicamente estáveis na alta hospitalar 6,7,43 .…”

Imunogenicidade da vacina contra hepatite B iniciada precocemente em pré-termos: implicações para a prevenção

“…In general, these studies included NB from a wide gestational age and birth-weight range, with the majority of the members of the sample groups having gestational ages close to 36 weeks or birth weights close to 2,000 g. 5,6 In contrast, other studies that have performed early vaccination on larger numbers of preterm NB whose birth weights were < 1,500 g or gestational ages < 32 weeks, 2,3,7-9 including a study we performed of Brazilian children, 10 have identified significantly lower levels of immunogenicity among preterm NB after the complete course of vaccination was completed (60-77%) than among full term NB (98-100%). While the study made by Sadeck & Ramos was not designed for this end, it too identified a reduced frequency of post-vaccination protective antibody levels within the subgroup of preterm NB born weighing less than 1,500 g. 4 What are the implications of reduced vaccination immunogenicity among preterm NB born at less than < 1,500-1,800 g and/or with a gestational age < 32-34 weeks for infant VHB infection prevention?…”

“…4 The two groups were compared b y means of testing for protective anti-HBs antibody levels (> 10 mUI/ml) before the third vaccine dose, at 9 months and at 12 months. Despite identifying a tendency, before the third dose was given, towards a lower frequency of protective antibody levels among preterm children, due to a reduced response to the first two doses from those whose gestational age < 34 weeks and/or, and more…”