9 week negative HBsAg definitive (?)

[neveragain131820]

I've looked, but can't find a for sure answer on this. Can someone clarify my interpratation of the below info on the CDC web site? I take this to mean, that a negative HBsAg on the antibody test at nine weeks means that the person was not exposed to/did not contract the Hep B virus:

From the CDC site:
         "HBsAg will be detected in an infected person’s blood an average of 4 weeks (range: 1–9 weeks) after exposure to the virus...."
         http://www.cdc.gov/ncidod/diseases/hepatitis/b/faqb.htm#b7

Thanks!

[cajim]

Are you sure you have been exposed to HBV?  If yes, it is safer to look for positive anti-HBs rather than negative HBsAg.  Why?  You may not be sure the time of exposure, so you may not know when is week 9; you don't know if the test messed up and did not pick up HBsAg, etc.  On the other hand, if you have positive anti-HBs, you know you are immune for life.

Best.

[neveragain131820]

Hi there -

My situation is... I know exactly when the potential exposure was. I also know I am currently:

HBsAg negative
anti-HBc negative
anti-HBs negative

So, I know I'm not immune due to due to natural past infection or immunization.

My main question is... if I continue to test "HBsAg negative" at nine weeks - according to the CDC verbiage - does that mean I have not contracted the Hep B virus?

(Reference: http://www.cdc.gov/ncidod/diseases/hepatitis/b/faqb.htm#b7
HBsAg will be detected in an infected person’s blood an average of 4 weeks (range: 1–9 weeks) after exposure to the virus...")

Thanks!

[cajim]

As I said, what if the test gave you false negative HBsAg, how do you know you are negative HBsAg 1-9 weeks?  On the other hand, if you are anti-HBs positive, you know you are fine.

My children were HBsAg negative but I did not feel safe until I saw their positive anti-HBs.

Hope this helps.

[neveragain131820]

I know that I am anti-HBc negative and anti-HBs negative. I've been tested twice. Same results.

Both tests also showed HBsAg negative. One test was at 4 weeks. The next at 6 weeks.

My anti-HBc is not going to change if I wasn't exposed. So, if my HBsAg stays negative... that is 3 tests negative.

Should't that verify I did not contract it?

Thanks!!

[zellyf]

The test is not definitive until 6 months following exposure.  It can take up to 6 months for the virus to start actively replicating.  However, if the virus doesn't show up early...I think by 6 or 9 weeks I don't recall exactly, google it, then your real risk of it showing up before the end of the 6 months is very low.

[cajim]

I agree with zellyf.  Maybe you should get vaccinated and get protected for life.

[neveragain131820]

OK, thanks. So my interprutation of the CDC info is pretty much correct.

Your response makes me wonder though. Yes, great idea to get vaccinated. But, if the virus is present (just not showing yet), would a vaccination do anything?

i.e. can you get vaccinated AFTER being infected and prior to onset of any symptoms and have it work?

[cajim]

Your presentation looks like you do not have HBV at all which is why vaccination makes a lot sense.  Should you already have HBV, vaccination would just have no effect.