O impacto da vacinação contra HBV entre adolescentes brasileiros requer mais atenção
Seyed Moayed Alavian; Seyed-Hossein Aalaei-Andabili
Baqiyatallah Research Center for Gastroenterology and Liver Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran
We read with great interest the article by Scaraveli et al. 1 recently published in your distinguished journal. Hepatitis B and C are the main causes of liver disease in the world, involving extensive morbidity and mortality 2,3,4. There are major differences in these infections between different areas of the world 2,5. Population-based studies are needed to better understand the issue in the community. We wish to call readers' attention to several key points. First, the study appears to have underestimated HCV and HBV infection rates because it failed to include children not enrolled in school and/or homeless children, who tend to be exposed to higher risk of infection. Prevalence rates for HCV and HBV infection are higher in street children 6; if the authors had enrolled the general population of adolescents in the study, they might have produced a more accurate estimate, as reported previously in Brazil (8.5%) 7. The students' participation rate in the study was not mentioned, and it would have been better to evaluate vaccination coverage before studying the vaccine's efficacy. In addition, it is necessary to know the long-term efficacy of vaccination, especially among adolescents. It would also be interesting to know whether there were any HBV-positive children among those with detectable anti-HBs. Subgroup analysis according to vaccination status would also be more informative of the vaccine's efficacy in Brazilians.
The study could have estimated differences in HCV and HBV infection between males and females, as it did for different kinds of schools, indicating the impact of socioeconomic status on HCV and HBV prevalence. We believe that other reasons should be found for the low HBV prevalence. Blood transfusion is not an age-dependent event. In addition, it is known that hemophilia and thalassemia patients receive blood and blood products during childhood. The group at highest risk of acquiring HCV infection is intravenous drug users (IDUs) 8. The mean age of IDUs is more than 16 years 9, and no one in their study was older than 16. This is one reason for the lack of HCV infection in the study sample. Finally, we wish to add that for adolescents, HBV vaccination is cost-effective and can improve control of HBV infection in the community 10.
S. M. Alavian prepared the preliminary draft and final version. S.-H. Aalaei-Andabili contributed to preparation of the preliminary draft.
The authors wish to thank Dr. S. M. Miri for his cooperation.
1. Scaraveli NG, Passos AM, Voigt AR, Livramento A, Tonial G, Treitinger A, et al. Seroprevalence of hepatitis B and hepatitis C markers in adolescents in Southern Brazil. Cad Saúde Pública 2011; 27:753-8.
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8. Alavian SM, Gholami B, Masarrat S. Hepatitis C risk factors in Iranian volunteer blood donors: a case-control study. J Gastroenterol Hepatol 2002; 17:1092-7.
9. Umar M, Bushra H, Ahmad M, Khurram M, Usman S, Arif M, et al. Hepatitis C in Pakistan: a review of available data. Hepat Mon 2010; 10:205-14.
10. Alavian SM, Gooya MM, Hajarizadeh B, Esteghamati AR, Moeinzadeh AM, Haghazali M, et al. Mass vaccination campaign against hepatitis B in adolescents in Iran: estimating coverage using administrative data. Hepat Mon 2009; 9:189-95.
Submitted on 25/May/2011
Approved on 27/Jun/2011