Please help me interpret - i am really worried

Question

Thank you Dr for taking the time and reading my post. I am HIV pos and have been on viraday since March 2016. I have been undetectable since November 2016. In March 2016, I was also tested for hep b and other stds which turned out to be negative. I was strongly advised to take the hep b vaccine. I started the series and the four shots were completed by November 2016. In December 2016 I tested the hbsab to make sure i am protected and the result was hbsab=400.69 miu/ml. I also tested for the antigen hbsag and it was negative. Yesterday I repeated the test for hbsab just to make sure I am still protected against hep b and to make sure the level of antibodies is still high. The results were: 71.70 miu/ml. My concern is:

1). why this rapid drop in antibodies in almost 7 months? What does it mean? Does it mean my immunity against hep b is low now?

2). Could it be that I am hep b positive and i am positive for hbsag and thats why the hbsab level dropped?

3). Do you recommend I take a booster shot to increase the level of antibodies and make sure they are above 70 miu/ml? Is it safe to have another booster?

I know I might sound silly to you, but I am really anxious and scared- just want to make sure I am protected against hep b.

Thank you again and hope you can help me out.

Answer

If a person has completed the HBV vaccine series, then a HBsAb titer of > 10 IU/mL is considered sufficient for immunity. So there is nothing further for you to do or worry about.