To ask the Secretary of State for Health what recent research he has (a) commissioned and (b) evaluated into the infectivity of hepatitis B. 
The Department has commissioned some owrk on hepatitis B virus deoxyribonucleic acid assays and on their use as a possible marker of transmissibility of hepatitis B infection.
To ask the Secretary of State for Health what is his Department's estimate of the proportion of babies born to mothers fected with hepatitis B who will also become chronically infected. 
The risk that a baby born to a mother infected with hepatitis B will become infected depends upon the relative infectivity of the mother. Studies indicate that transmission rates of around 10 to 20 per cent. or less may occur with mothers of low infectivity but these may rise to 70 to 90 per cent. with highly infectious carrier mothers. About 90 per cent. of babies infected perinatally by a highly infectious mother will become chronic carriers of hepatitis B virus; those infected by mothers of low infectivity have a much lower risk of becoming carriers. These figures are in the absence of immune prophylaxis.
To ask the Secretary of State for Health how many hepatitis B carriers there are in the United Kingdom. 
The number of chronic carriers of hepatitis B in the United Kingdom is not known precisely. Available data indicate that the UK, in common with other north-western European countries, has one of the lowest prevalence rates of hepatitis B carriers in the world, being around 0.1 to 0.2 per cent. The carriage rate in the UK will vary with geographical location, being low in some rural areas and higher in some inner cities where there are aggregations of high-risk groups.