Final answer:
More than one blood test may be necessary to determine if a person has HBV due to the possibility of false positive or false negative results.
Step-by-step explanation:
True. More than one blood test may be necessary in some cases to determine if a person has HBV. This is because initial blood tests can result in false positive or false negative results. False positives may occur if the patient has been previously infected by other pathogens that elicit antibodies that cross-react with HBV antigens. False negatives can occur if the patient's immune system has not produced detectable levels of antibodies yet. Therefore, a second, confirmatory test is often required to rule out false results and definitively diagnose HBV infection.