CORRESPONDENCE SECTION

Hepatitis B vaccination in preterm infants

Sir,I read the recent article ‘‘Immunogenicity of hepatitis Bvaccine in term and preterm infants’’ by Belloni et al. (1)with interest. However, I could not agree entirely with theirconcluding last sentence, ‘‘vaccination of newborns whosemothers are not hepatitis B carriers could be initiated inclinically stable infants, even if their weight is below2000 g.’’ Their conclusion may be justified for newbornswith birthweight$1500 g, but certainly their data for those,1500 g are rather weak, based on only 17 newborns.Moreover, they have excluded newborns with infections,congenital malformations, asphyxia, sepsis, severe respira-tory distress syndrome or intraventricular haemorrhage,which are all common complications for preterm infants,especially those,1500 g. The one study by del Canho et al.(2), which they quoted in support of their conclusion in factonly included newborns who were rather mature (median36 weeks; range 27.2–36.6 weeks) and of reasonable birth-weight (median 2540 g; range 1200–3950 g) (3). Indeed,the only preterm infant in del Canho’s study who did notseroconvert weighed,2000 g and vaccination was startedat birth. Since there were only 9 preterm infants withbirthweights,2000 g in their study, this would give aseropositive rate of 88% (8/9) for this group. The studyof Kim et al. (4), which they quoted to be at odds with theirfindings, reported a seroconversion rate of only 90% for agroup of 87 preterm infants, even when the first dose wasdelayed until just before hospital discharge. We alsoreported the immune response of 99 preterm infants withbirthweights,1750 g to hepatitis B vaccine (5). Fifty-seven received the first dose when they weighed$1000 g(Group 1) and 42 were first immunised when theyweighed$2000 g (Group 2). The final seropositive ratesand geometric mean titres of Group 1 infants (79%; 61 IU/l)

and Group 2 infants (91%, 262 IU/l) were less than those of43 normal term infants (100%, 679 IU/l). There were nosignificant differences between Group 1 and Group 2 inmean (6SD) gestational age (30.86 3.0 vs 31.36 2.3weeks) and mean (6SD) birthweight (13366 253 vs13136 247 g).

Based on the available data, we cannot agree withBelloni et al.’s support (1) of the recommendation toadminister HBV vaccine at the ‘‘appropriate chronologicalage’’, i.e. starting at birth, for infants even if their weight is,2000 g (2).

Firm recommendations cannot be made at the momentfor the preterm infants. The most reasonable approach forthe time being is to delay hepatitis B vaccines until thepreterm infants reach a body weight of 2000 g, or justbefore discharge if their mothers are not hepatitis Bcarriers. If their mothers are hepatitis B carriers, thesafest approach is to give the vaccine with HBIG at birthand evaluate their response as they may need a fourth doseas in some immunocompromised patients.

References1. Belloni C, Chirico G, Pistorio A, et al. Immunogenicity of hepatitis B

vaccine in term and preterm infants. Acta Paediatr 1998; 87: 336–82. del Canho R, Grosheide PM, Gerards LJ, et al. Hepatitis B vaccination

and preterm infants. Pediatr Infect Dis J 1993; 12: 407–83. Lau YL. Hepatitis B vaccination in preterm infants. Pediatr Infect Dis J

1994; 13: 2434. Kim SC, Chung EK, Hodinka RL, et al. Immunogenicity of hepatitis B

vaccine in preterm infants. Pediatrics 1997; 99: 534–65. Lau YL, Tam AYC, Ng KW, et al. Response of preterm infants to

hepatitis B vaccine. J Pediatr 1992; 121: 962–5

YL Lau, Department of Paediatrics, Queen Mary Hospital, University ofHong Kong, Hong Kong

Hepatitis B vaccination in preterm infants: a reply to Lau

Sir,In response to the letter concerning ‘‘Immunogenicity ofhepatitis B vaccine in term and preterm infants’’ (1), thevaccination of preterm infants against hepatitis B remains amatter of debate, as evidenced by the different conclusionsreached by the studies published so far. Lau has adopted aconservative approach, suggesting a delay in vaccinationuntil very low birth weight infants reach a weight of at

least 2000 g. We, however, wish to emphasize that in ourstudy (1), which included only clinically stable infants, nosignificant differences were observed in the response tovaccination between term and preterm infants.

The seropositive rate of 97.5% (39/40) in infants weighing,2000 g at birth did not differ appreciably from the corre-sponding percentages in infants with normal birth weight(2500 g) (table 2 in the above-mentioned paper) and, more

Acta Pædiatr 87: 1100–4. 1998

q Scandinavian University Press 1998. ISSN 0803-5253