It is not quite true to say that loss of antibodies indicates loss of immunity. There is a well known concept called immune memory. The fact that antibodies were quickly produced after a single booster and in such high number is a proof of this concept. Of course, for persons who are at risk of exposure to HBV, such as doctors and nurses, a booster is prudent. Some doctors would say you are protected after producing HBsAb > 10 iu/L after vaccination and this protection is good for at least 30 years as indicated by a recent research study.
http://www.medscape.com/viewarticle/857886
Thanks for sharing your story with us; it was very wise of you to re-vaccinate your family and you were quite lucky because they already had lost their immunity. It is a pity that most GP's even today do not have enough knowledge about hbv. I was diagnosed with hbv last spring; my doctor never asked me if I had a sexual partner , and hence never warned me about transmission modes of hbv. I had to do my own research and get more information from the internet on my own.
To andyblaze,
As long as you are HbsAg positive, you are infectious to others. Make sure your sexual partner is vaccinated and gained immunity against hbv before any unprotected sexual contact.
Unless your hbsag is clearly bellow 1000 IU (which together with ALT bellow 30 for males and bellow 19 for females would most likely indicate that you are indeed inactive hepatitis carrier), you should follow your ALT and DNA every 6 months to make sure you are indeed not active....
You should not have unprotected sex as viral load tends to go up and down for some of hep b positive people...so it might be the case when you have sex that your viral load is up and you become more infectious to other person.
Instead you should vaccinate the other person....
I was told that I m Inactive carrier after diagnosis, I had undetectable viral DNA. I didn't transmit it to my wife after 3.5 years of marriage also. I have vaccinated to her now and she got antibodies now.
I am not sure the same holds good for all inac tive carriers.