Hepatitis affects hundreds of millions of people worldwide killing 1.45 million people. 1,280,000 die from the B and C viruses alone. Putting that in context; hepatitis represents 2.5% of all annual deaths [based on WHO 2012 figures.] With today being World Hepatitis Day, we wanted to take a look at the current state of hepatitis treatments for viruses.
Hepatitis A – HAV
Hepatitis is primarily a risk in areas with poor hygiene/sanitary conditions as it typically spread via the fecal-oral route. No current drug exists for infection by HAV. Vaccines for Hepatitis A exist as a live, attenuated virus, inactivated virus or virosome. The vaccines are highly effective and public vaccination campaigns have reduced infections by 90% in the USA.
Hepatitis B –HBV
Transmitted through infected blood or bodily fluids, Hepatitis B chronically infects 240 million people worldwide. In most people anti-viral treatment lasts a lifetime. Entecavir, a reverse transcriptase inhibitor, is listed by the WHO as an essential medicine. The WHO also lists the reverse transcriptase inhibitor Tenofovir, a treatment which is also used in treatment of HIV-1. Effective vaccines are available for Hepatitis B; predominantly these are recombinant DNA vaccines.
Hepatitis C – HCV
Hepatitis C is transmitted through blood and unsterilized injection practices are a key cause of infection. The treatment options for HCV infection differs from that for HAV and HBV in that no vaccine is currently available, but a number of treatments have become available in the last five years.
Merck’s Boceprevir, a protease inhibitor was approved by the FDA in 2011. Another protease inhibitor, Telaprevir, was developed by Vertex Pharmaceuticals and Johnson and Johnson was also approved in 2011, however production has been discontinued by Vertex. Simeprevir is a NS3/4A protease inhibitor developed by Medivir and Johnson & Johnson. Sofosbuvir and Ledipasivir are more recent additions to the treatment options. Sofosbuvir is an inhibitor of HCV’s RNA polymerase, while Ledipasivir inhibits HCV replication protein NS5A (other drugs targeting NS5A include Daclatasivir and Ombitasivir).
Some of these treatments have come under criticism for their exorbitant cost (tens to hundreds of thousands of dollars for one treatment course,) which puts them out of reach of many in Africa and Central and East Asia, the most affected regions. Gilead responded to these criticisms in 2014 by allowing generic manufacturers to produce Sofosbuvir in developing regions.
Hepatitis D & E - HDV & HEV
Hepatitis D (HDV) can only propagate in the presence of the Hepatitis B virus (HBV), thus vaccines for HBV are effective at preventing HDV. HEV is self-resolving and does not infect chronically, it is treated only with supportive therapy.