Hepatitis B vaccination among the Nicobarese tribe: Need to document the impact.

Sir,

Hepatitis B virus infection was found be hyperendemic among the tribes of Andaman and Nicobar islands, with HBsAg positivity ranging from 4 per cent among the Great Andamanese, 23 per cent among Nicobarese, 31 per cent among Onges, 38 per cent among Shompens to 66 per cent among Jarawas1. Following the reports of high endemicity among these tribes, hepatitis B vaccine was introduced in the childhood vaccination programme for tribal as well as non-tribal children in these islands. Sugunan et al2 in their study on seroprotection after hepatitis B vaccination among the Nicobarese tribe of Andaman and Nicobar islands reported that 86 per cent of the Nicobarese who received three doses of hepatitis B vaccine (Shanvac B) were seroprotected five years after the vaccination. It is reasonable to believe that the hepatitis B vaccine/s used in the childhhod vaccination programme since 2005 are of comparable immunogenicity (and efficacy) as that of Shanvac B.

In India, there are limited data about the impact of hepatitis B vaccination programme3. Seroprotection is not an ideal indicator to measure the ‘impact’ of vaccination. Three indicators are generally recommended: vaccination coverage, prevalence of HBsAg among young children and reduction in the prevalence since vaccination and reduction in the incidence of liver cancer4. As per the Coverage Evaluation survey 2009, the combined coverage of hepatitis B vaccine in Andaman and Nicobar, and Lakshdweep islands was 47 per cent for the birth dose, 75 per cent for the first, 72 per cent for the second and 66 per cent for the third dose5 Information about the incidence of liver cancer is not available from Andaman and Nicobar islands. It has been nearly a decade since the hepatitis B vaccination programme was initiated in these islands. It is very timely that a serosurvey is conducted in these islands to estimate the prevalence of HBsAg among Nicobarese children, document the reduction in the prevalence and thereby measure the ‘real impact’ of hepatitis B vaccination programme.