Hello Dr. I am msle, 32 years. I have a query, i have taken HBsAg (surface antigen) blood test after 85 days(12weeks) after oral exposure(fellotia) in a parlour and was negative. Only oral fellotia was the exposure., no other exposure. In the test report, it was mentioned false negative can be due to virus mutations of hepatitis B virus. Need to know 1) is test after 12 weeks of exposure,  conclusive. 2) do i need to worry about Hepatitis B virus mutation and false negative because of this  Or is  mutation a very rare and insignificant phenomenon , and further testing is not required. Kindly guide. Thanks s lot in advance.