Current status of HBV vaccine escape variants – a mathematical model of their epidemiology

Source abstract

We present a deterministic model of the possible emergence of a vaccine escape variant of hepatitis B virus (HBV). The model identifies the key unknowns determining this process: the protection afforded by the current vaccines against particular HBV variants; the infectiousness of these variants; and the current prevalence of individuals infectious with the variants (each factor relative to wild‐type). By making pessimistic assumptions about these unknowns we show that even a highly infectious variant, under a vaccine programme that affords no protection against the variant, would still take decades to emerge. Thus the current low prevalence of variants is not evidence for the cross‐reactivity of the current vaccines or for a lack of infectiousness in the variants. As any vaccine failure will be inapparent for decades it may be sensible to recommend vaccine modifications now rather than later.