Unexplained fever in neonates may be associated with hepatitis B vaccine

Aim-To investigate whether hepatitis B vaccination has increased the number of cases of unexplained neonatal fever. Method-The files of all infants born from 1 January 1991 to 31 December 199 2, in whom a diagnosis of "injected antibiotic" or "disease of temperature regulation" was recorded, were reviewed. Those who had unexplained fever of 38 degrees C or higher during the first three days of Life were divided in to two groups: infants who did not receive the hepatitis B vaccine (1991) a nd infants who did (1992). Results-In 1992 the incidence of unexplained fever in hepatitis B vaccinate d neonates was significantly higher than in the 1991 group of pre-vaccinati on neonates (35 out of 5819 (0.6%) vs 14 out of 5010 neonates (0.28%) respe ctively, p=0.013). Conclusions The increase in the number of cases of unexplained neonatal fev er seems to be associated with the introduction of routine hepatitis B vacc ination on the first day of life. The possibility that an excess number of neonates will undergo unnecessary procedures and treatment to diagnose unex plained fever justifies planning a controlled study to determine whether th ese preliminary findings point to a significant problem.