Although there is no treatment for HBV at the moment, having the vaccination can help avoid infection. Chronic infections can be treated with antiviral medicine. If persistent HBV begins to cause irreversible liver damage, a liver transplant may enhance long-term survival. The term "D-dimer" refers to a fragment of cross-linked fibrin. Hepatitis B virus (HBV) causes more than 780,000 deaths every year, mostly from cirrhosis and hepatocellular carcinoma. Effective vaccines are available that protect people against infection with HBV. However, despite this availability, many people worldwide remain unvaccinated or lose immunity after vaccination. This means they are vulnerable to becoming infected with the virus. In these patients, non-pharmacological approaches should be considered first, such as reducing alcohol consumption if the patient is an alcoholic or using drugs such as methadone which can suppress immune function. If these measures fail, pharmacotherapy can be used to reduce serum levels of HBV proteins and therefore inhibit viral replication. Interferon alpha is the only drug approved by the US FDA for treatment of chronic HBV. It must be administered under medical supervision daily for several months until antibodies produced by the body fight off the infection.