Vaccine-Induced Anti-HBs Level in 5-6 Year-Old Malnourished Children

Background: Malnutrition is the most common cause of immune deficiency. It results in reduced secretion of T-cells and B-cell-stimulating factors leading to declining of special immunoglobulins. On the other hand, hepatitis B, as a major world health problem, can be prevented effectively by vaccination. Three doses of hepatitis B virus (HBV) vaccine induce protective levels of anti-hepatitis B surface (anti-HBs) in 95% of healthy children. This level decreases gradually over time.

Objectives: The goal of this study was to assess anti-HBs in malnourished children, who confronted to some degrees of immune deficiency.

Patients and methods: This is a cross-sectional study conducted during May to August 2010 in therapeutic clinics of Yazd, Iran. Samples were selected simply and consecutively among 5-6 year-old children with a history of three doses of HBV vaccine in infancy. On the basis of World Health Organization's definition on malnutrition, which considers anthropometric measurements, malnourished children entered the study. Totally 83 cases (37 boys and 46 girls) were gathered and classified into three groups of mild, moderate, and severe malnutrition. One milliliter of venous blood was taken and anti-HBs were tested by enzyme linked immunosorbant assay (ELISA).

Results: Overall, seroprotection rate and geometric mean titer (GMT) of anti-HBs were 60.2% and 15.47 ± 10.92 mIU/mL, respectively. Seroprotection rate was 71.4%, 55.2%, and 72.7% in mild, moderate, and severe malnourished children, respectively. GMT was 30.78 mIU/mL, 12.15 mIU/mL, and 22.95 mIU/mL in these groups, respectively. None of these two indices were significant in these groups (P = 0.471, P = 0.364). Seroprotection rate and GMT were 54.1% and 13.26 ± 11.59 mIU/mL in boys, and 65.2% and 17.5 ± 10.59 mIU/mL in girls, respectively, showing no significant relationship with gender (P = 0.302, P = 0.602). Lowest seroprotection rate was in stunted cases (47.1%) and highest in wasted children (77.8%). This difference also was not significant (P = 0.43).

Conclusions: The seroprotection rate and GMT of anti-HBs observed in this study do not show a high level of immunity. These two indices were not related to severity of malnutrition. We conclude that severity of malnutrition does not affect vaccine-induced antibody level and seroprotection rate; however small sample size in each group of study hinders decisive conclusion. Moreover, GMT and seroprotection rate showed no relationship with type of abnormal anthropometric index, including weight for height, weight for age, and height for age.