Millions of people are HepB carriers and don't know it. The virus can take many years to demonstrate itself before it causes problems, but it is highly contagious long before it demonstrates any symptomology.
Anyone who advocates NOT having it when you are already having a HepA vaccine is not giving good advice!
Statistically, it is much more likely to cause an infection than HIV virus.
Years ago the statistics were:
A needle stick from a needle used on an HIV patient was likely to cause HIV infection 1 in 200-300 sticks.
A needle stick from a needle used on a HepB patient was likely to cause HepB infection at least 1 out of 3 times.
HepB is much tougher to kill, the virus can live on dry surfaces for long periods, and can't be killed with a low concentration bleach solution near as easily as HIV can.
HepB is much more virulent than HIV is, and many HepB patients develop HepC, though we aren't 100% sure why or how.
Finally, although it is a bloodborne pathogen, I have seen patients who have contracted it and we have never figured out the vector they were exposed to.
The saddest case was a school teacher with Liver Ca who contracted HepB and HepC because he stopped to help a guy who had been assaulted. There was a lot of blood, both from the victim and the assailant, and by the time anyone realized what had happened, the victim was also positive. No one knows if the victim had it prior to the assault, (he didn't know if he did). The assailant (never found) may have been the carrier, but we'll never know. This was in the Late '80's, imagine how many more people have it now!!
Some blood drives at high schools have shown as high as 10-20% positives, I've heard, but I suspect that may be one of those urban myths.
Bill