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.

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.

Prevalence and epidemiological profile of Hepatitis B in pregnant women: a population study in a Brazilian Western Amazon city from 2007 to 2015 / Prevalência e perfil epidemiológico da Hepatite B em gestantes: um estudo populacional em uma cidade da Amazônia Ocidental brasileira, no período de 2007 a 2015

Abstract Objectives: this study aimed to describe the epidemiological profile and prevalence of hepatitis B infection in pregnant women living in Rio Branco, Acre, Brazil. Methods: this was a cross-sectional study concerning the prevalence of Hepatitis B in a cohort of women who gave birth in Rio Branco from 2007 to 2015. Data were obtained through health information systems. Pregnant women presenting one or more serological markers or positive molecular biology examination were considered confirmed cases of infections. Infection prevalence, the odds ratio (5% significance) and sociodemographic, clinical, obstetric and neonatal variable frequency distributions were calculated. The student's t-test and Mann Whitney test were applied, as well as the chi-square test or Fisher's exact test, at a significance level of 5%. Results: a total of 62,100 pregnant women were identified for the study period. The prevalence of Hepatitis B in the group was of 0.38% (206 cases), and only 12,5% were diagnosed during the first gestation trimester. A significant difference (p=0.034) in the mean age of infected women was observed when compared to those without infection. The chance of an infected pregnant woman giving birth to a child with a 1st Apgar minute <7 was of 2.01 (CI95%= 1.09-3.71; p=0.995), higher than observed for healthy pregnant woman. Concerning infected patients, the most reported risk exposure was dental treatment (19.2%). Conclusions: the prevalence of Hepatitis B among pregnant women was lower than reported in other national studies. Low Hepatitis B detection during the first gestation trimester was identified, which reinforces the need to intensify early diagnosis during prenatal follow-up, especially due to the severity of the disease and the possibility of vertical transmission.

Resumo Objetivos: descrever o perfil epidemiológico e prevalência da infecção de hepatite B em gestantes residentes em Rio Branco, Acre. Métodos: estudo transversal da prevalência de hepatite B na coorte de mulheres que gestaram em Rio Branco de 2007 a 2015. Os dados foram obtidos através dos sistemas de informação em saúde. Foi considerado caso confirmado de para a infecção a gestante que apresentasse um ou mais marcadores sorológicos ou exame de biologia molecular. Foi calculada a prevalência da infecção, razão de chance (significância de 5%) e distribuição de frequências de variáveis sociodemográficas, clínicas, obstétricas e neonatais. Calculou-se o teste t de Student e Mann Whitney além do teste do qui-quadrado ou exato de Fisher, com significância de 5%. Resultados foram identificadas 62.100 gestantes no período de interesse. A prevalência de hepatite B no grupo foi de 0,38% (206 casos). Destas, apenas 12,5% foram diagnosticadas no 1º trimestre da gestação. Houve diferença significativa (p=0,034) na média de idade das infectadas quando comparadas às sem infecção. A chance de uma gestante infectada ter um filho com Apgar de 1º minuto <7 foi 2,01 (IC95%: 1,09-3,71; p=0,995) vezes maior que uma gestante saudável. Das pacientes infectadas a exposição de risco mais relatada foi o tratamento dentário (19,2%). Conclusões: a prevalência de hepatite B entre gestantes foi inferior à encontrada em outros estudos nacionais. Foi identificada uma baixa detecção de hepatite B no primeiro trimestre gestacional, o que reforça a necessidade de intensificar o diagnóstico precoce durante o seguimento de pré-natal, especialmente pela gravidade da doença e possibilidade da ocorrência de transmissão vertical.