A worldwide vaccination programme against hepatitis B (HBV) may be streng thening the virus rather than wiping it out.
According to Arie Zuckerman of the WHO Collaborating Centre for Reference and Research on Viral Diseases in London, the vaccine may be losing its efficacy. Moreover, it is apparently producing different mutations of HBV as well (Lancet, 2000; 355: 1382-4).
As evidence, he cites data from several countries where vaccination is carried out on a large scale. In Taiwan, the prevalence of the mutated virus rose from 7.8 per cent when the vaccine was introduced in 1984 to 19.8 per cent in 1989 and to 28.1 per cent by 1994.
The prevalence of HBV mutations was higher among those who had been fully immunised than among the unvaccinated. Findings in countries such as the Gambia and Singapore suggest that these mutations are not merely the result of vaccine failure (Lancet, 2000; 356: 769-70).
As many as 10 per cent of vaccinated adults produce no antibodies to the virus and, within seven years, as many as 50 per cent of vaccinated people lose detectable antibodies.