Levels of hepatitis B antibody titers are affected by age and doses gap time in children from a high endemic area of the western Amazon
Laura Cordeiro Gomes, Marina Cordeiro Gomes Sanson, Philip Brainin, Maria da Conceição Vieira de Melo, Rodrigo Medeiros de Souza, Janaína Mazaro, Karine O. Lima, Júnia Silva Resende, Isabelle V. M. Vieira, Edinilson da Silva Mesquita, Luan O. Matos, Isabelle Caroline Silva Dutra, Giuseppe Palmisano, Carsten Wrenger, Cláudio Romero Farias Marinho, Rita do Socorro Uchôa da Silva
Abstract
BACKGROUND: Despite completion of the vaccine schedule for hepatitis B virus (HBV), children may display levels of HBV surface antibodies (anti-HBs) that are considered inadequate for sufficient protection (<10 IU/L). AIMS: Our aim was to investigate if age and gap time between HBV vaccine doses may negatively affect the levels of anti-HBs in children, and if these relationships are modified by sex. METHODS: In a high-endemic HBV region of the western Brazilian Amazon we enrolled children who had completed the HBV vaccine schedule. All children underwent analysis of anti-HBs and a clinical examination. RESULTS: We included 522 children (mean age 4.3 ± 0.8 years; 50% male). Median anti-HBs was 28.4 [interquartile range (IQR) 5.4 to 128.6] IU/L and 32% had anti-HBs <10 IU/L. The median gap time from last to preceding dose was 2.4 [IQR 2.1 to 3.3] months. Levels of anti-HBs decreased with higher age (-42% per year increase [95%CI -56% to -24%], p<0.001), but not with longer gap time (+23% per month increase [95%CI -16% to +62%], p = 0.249). After adjusting for relevant confounders, gap time became significant (p = 0.032) and age remained a significant predictor of anti-HBs (p<0.001). CONCLUSION: One third of assessed children displayed anti-HBs <10 IU/L. Levels of anti-HBs decreased with higher age and increased with longer gap time between the last two doses.