Immunogenicity of two Schedules of hepatitis B vaccine: effect of birth weight and gestational age

Introduction and aim of the work: Hepatitis B is a global problem causing both acute disease and delayed morbidity. The optimal time to initiate hepatitis B vaccination in low birth weight infants has not been determined. The aim of this work was to study the immune response of low birth weight infants whether full- term or prematures with two different schedules of hepatitis B vaccine, m order to optimize the time of hepatitis B vaccination of these infants. This study was conducted on 74 infants. They were 54 low birth weight [LBW] infants with birth weights<2.5 kg and 20 full-term healthy infants with birth weight appropriate for gestational age [AGA] who were served as controls. The 74 infants were followed up from birth at 3-months interval and completed the follow-up period at the age of 12 months. According to the hepatitis B vaccination schedule given, the studied infants were divided into two groups; group I comprised 38 infants who received hepatitis B vaccine at the 2nd, 4th and 6th months of age [1st schedule] and group II comprised 36 infants who received the vaccine at birth, 1st and 6th months of age [2nd schedule]. Considering the birth weight and gestational age, infants group further subdivided into subgroup A which: included full-term LBW infants [IA and IIA], subgroup B which included preterm infants [IB and IIB] and subgroup C which included full-term AGA infants [IC and IIC]. All mothers were subjected to full medical history taking and assessment of socio-economic class as well as assessment of gestational age and anthropometric measures of their infants. Quantitative measurement ofanti-HBsAg levels using ELISA technique was done to all infants at birth then at the 3rd, 6th, 9th and 12th months of age. The mean levels of anti-HBsAg titre were significantly lower at all ages among LBW infants of groups I and II compared to those of subgroups 1C [full- term AGA of group I] and IIC [full-term AGA of group II] respectively. Meanwhile, the mean levels of the titre were significantly higher at the 6th and 9th months and significantly lower at the 3rd month of age in LRW infants of group I those of group II, while no significant difference between both groups was found at the 12th month of age. Regarding infants receiving the 1st schedule, the mean levels of anti-HBsAg titre were significantly higher at the 3rd and 6th months of age in infants of subgroup IA [full-term LBW of group I] than those of subgroup IB [prematures of group I], while no significant differences between the 2 subgroups were found at the 9th and 12th months of age. Meanwhile, the mean levels of anti-HBsAg titre were significantly lower in subgroup IA infants compared to those of subgroup 1C at the 6th and 9th months of age and in infants of subgroup IB compared to those of subgroup 1C at all ages. Regarding infants receiving the 2nd schedule, the mean levels of anti-HBsAg titre were significantly higher in subgroup IIA infants [full-term LBW of group II] than those of subgroup IIB [prematures of group II] at all ages and significantly lower in subgroup IIA infants compared to those of subgroup IIC [full- term AGA of group II] at the 6th, 9th and 12th months of age and in infants of subgroup IIB compared to those of subgroup IIC at all ages. Comparing the two schedules, the mean levels of a@@@@@@nti HBs Ag titre were significantly higher in subgroups IIA, IIB and IIC infants compared to those of subgroups IA, IB and 1C respectively at the 3rd month of age and in infants of subgroup IB compared to those of subgroup IIB at the 6th, 9th and 12th months of age. However, there were no significant differences regarding the mean levels of the titre among subgroups IA and 1C infants compared to those of subgroups IIA and IIC respectively at the 6th, 9th and 12th months of age. Conclusion and Recommendations: We can come to the conclusion that the immune response to the different schedules of hepatitis B vaccine is lower in LBW as well as preterm infants. Further, the immune response of LBW infants to Hepatitis B vaccine given at birth, 1st and 6th months of life was higher at the 3rd month of age, while, at 6th and 9th months of age, the response to the vaccine was better in infants who received the 2nd, 4th and 6th months' schedule. However, by the end of the 1st year both schedules gave similar seroprotection regardless the gestational age and birth weight. Hence, in case there is no risk of perinatal transmission, it is recommended to delay the 1st dose of hepatitis B vaccine in LBW infants especially prematures till the age of 2 months and / or till the weight is >/= 2.5 Kg.

Serological status of mumps in non-immunized Egyptian infants

The present study was conducted on 2114 infants divided into different age groups ranging from 6-18 months. All studied infants were subjected to full history taking, thorough clinical examination and laboratory investigation for semiquantitative measurement of mumps IgG by ELISA technique. The study revealed that maternally acquired mumps seropositivity wanes out gradually reaching its nadir level at the age of 12-13 months. Therefore, infants in this age period have a greater risk to develop mumps infection with either higher morbidity or mortality. Hence, the study recommended that MMR vaccination should be adopted at 12-13 months of age in the expanded program of immunization in Egypt as being the time of waning out of passively acquired mumps IgG