Routine vaccines, extraordinary impact: Hepatitis B
Hepatitis B kills more people each year than AIDS-related illnesses, yet an effective vaccine exists. Ensuring every child has access to it is crucial to fighting back.
- 4 November 2021
- 8 min read
- by Linda Geddes
It is often referred to as the silent killer, because for years the infection can go undetected, quietly spreading to other people, before symptoms of severe liver disease or liver cancer become apparent. In other cases, the infected person never becomes seriously ill, but the discovery that they’re carrying the virus can condemn them to decades of worry.
Approximately nine in ten infants who catch the virus develop chronic hepatitis B, and roughly a quarter of them will eventually die from severe liver disease – which is why infant and childhood vaccination against HBV is so important.
“Whenever I get a pain in my side, it is always accompanied by the anxiety of ‘Is this liver cancer, is my liver being damaged?” says Dr Thomas Tu, a hepatitis B researcher at the University of Sydney in Australia who discovered he was infected with hepatitis B virus when he was 14.
“Even something as benign as holding a baby: I have to really watch myself, because there is this potential that I could transmit the virus to this child through small scratches, or something like that. Both myself and the baby would need to have scratches for transmission to occur, because the virus is spread through blood. But there’s always that anxiety at the back of my head.”
The first description of epidemic jaundice was on Sumerian clay tablets from the third millennium BCE. The Sumerians believed the cause was a devil called Ahhazu who attacked the liver – the home of the soul. Epidemic jaundice was also reported by the Greeks and Romans during the Middle Ages and during various military campaigns including the Siege of Saint-Jean-d’Acre in 1799, as well as during the American Civil War.
Often silent, sometimes deadly
A hundred times more infectious than HIV, and responsible for around 884,000 deaths globally each year, hepatitis B has never gone away. But without routine childhood immunisation, the global toll of deaths and severe illness related to this disease would be many times worse. And, although immunisation is drastically cutting the rate of infections among children and adolescents, the large pool of existing carriers and the difficulty of ensuring that vaccinated children receive all three doses, means hepatitis B remains a major public health challenge.
Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). Some people who catch it are only ill for a few weeks (an acute infection), with symptoms such as yellowing of the eyes and skin, dark urine, nausea, vomiting, abdominal pain and extreme tiredness. A proportion of them will develop liver failure and die, but others experience no symptoms.
Around 95% of adults who survive this initial infection successfully clear the virus from their bodies with no further health consequences. However, the younger a person is when they are infected, the greater the risk that they will develop a lifelong infection called chronic hepatitis B, which can eventually lead to severe liver damage (cirrhosis) or a type of liver cancer called hepatocellular carcinoma.
Approximately nine in ten infants who catch the virus develop chronic hepatitis B, and roughly a quarter of them will eventually die from severe liver disease – which is why infant and childhood vaccination against HBV is so important. Among adults and older children who become chronically infected with HBV, about 15% will die from hepatitis-related complications.
“The pernicious thing about hep B is that you may be infected when you’re born, but the symptoms don’t come up until 40, 50, 60 years later, when the first sign that you have hep B could be that your liver is failing, or you have liver cancer,” says Tu, who is now aged 35. “By that time, it is too late to do anything about it.”
Stigma ruins lives
The virus is transmitted in body fluids, such as blood or semen, with some adults having been infected as a result of blood transfusions or contaminated medical equipment, as well as through needle-sharing or unprotected sex.
Unfortunately, this creates a stigma around the disease which can leave those diagnosed with it feeling even more lonely and isolated. However, the majority of chronic hepatitis B infections occur during or very soon after birth as a result of transmission from an infected mother to her child. This is most likely how Tu became infected. The virus can also be passed from child to child through, for example, scratches acquired during rough play or sharing toothbrushes.
“I have cared for several young women (likely infected at birth) who were devastated when they discovered they had HBV infection, due to incorrect beliefs about likely routes of virus transmission. They could not understand how they had become infected, as they were still virgins and had no history of injecting drug use,” says Dr Mark Douglas, a virologist and infectious diseases specialist at Westmead Hospital and the University of Sydney, who regularly treats patients with chronic hepatitis.
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“One young woman had been beaten by her father, ostracised by the whole family and thrown out of her home. In other cases, marriages were under threat after [the male or female partner received] a diagnosis of HBV, because of perceived infidelity.”
Vaccine development and coverage
HBV isn’t the only cause of viral hepatitis – hepatitis A, C, D and E viruses also exist. However, it wasn’t until the early 1960s that the surface protein of HBV was discovered, paving the way for diagnostic tests that could distinguish between these different viruses, as well as the first vaccine against HBV.
The current hepatitis B vaccine is a protein-based subunit vaccine, containing the HBV surface antigen (HBsAg) – a protein found on the surface of the virus. The World Health Organisation (WHO) recommends that all infants receive the vaccine as soon as possible after birth, preferably within 24 hours, followed by a further two or three doses at least four weeks apart. Protection lasts at least 20 years and is probably lifelong.
Between 1990 to 2019, the proportion of children getting all three doses of the vaccine soared from 1% to 85% globally. This has substantially reduced transmission of the virus during the first five years of life, with chronic HBV infections among under-fives now at less than 1%, down from around 5% during the pre-vaccine era. However, success across regions is uneven. Although 14 countries in Africa have achieved a prevalence of less than 1%, across sub-Saharan Africa it is closer to 2.5%.
Coverage with the initial birth dose is also relatively low at 43% globally, and only 6% in the WHO African Region. A key issue is accessing mothers within 24 hours of giving birth in countries where births are often not supervised by medical professionals. In November 2018, the Gavi Board decided that, subject to availability of funding for the 2021 to 2025 strategic period, it would make support available for rolling out hepatitis B birth doses across lower-income countries.
The WHO has also set a target of eliminating viral hepatitis caused by hepatitis B and hepatitis C as a public health threat by 2030. Doing so will require more than boosting rates of childhood vaccination, as the preventative vaccine has no impact on existing infection. According to the WHO, there were 296 million people living with chronic hepatitis B infection in 2019, with 1.5 million new infections each year.
The power, and limitations, of hepatitis B treatment
Increased screening and diagnosis of adults is essential – particularly expectant mothers. If they test positive, the WHO recommends giving antiviral drugs to suppress levels of virus in their bodies, and reduce the risk of transmission to their babies. Antiviral drugs can also be taken by other adults who are chronically infected with HBV to suppress levels of the virus in their bodies.
“The limitation of that medication is that it’s considered as a lifetime treatment,” says Tu. “As soon as you stop taking those drugs, the virus comes back, and so what you’re asking people to do is to take and buy medications for the rest of their lives, which is not accessible to many people.”
Other strategies include wider implementation of blood safety strategies, such as screening blood donors, ensuring medical equipment is properly sterilised, and safer sex practices, including the use of condoms.
A major focus for hepatitis B researchers such as Tu is the development of drugs that could clear the virus from people who are chronically infected with it. Although the virus has been with us for millennia, it is only in the past 15 years that researchers have mastered techniques for growing it in the laboratory, and infecting cells – an essential step towards finding a cure.
Until that happens, Tu advises those infected with HBV to equip themselves with knowledge and to find support by connecting with other infected people. To this end, he has set up a global peer-led, volunteer-driven forum called HepBCommunity.org, to support to those living with and affected by hepatitis B.
It is important that people realise they are not alone, he says: “Almost 300 million people around the world also have this condition; that’s twice as many people as those who have green eyes.
“The other important thing to know is that a hepatitis B infection is not a death sentence in most cases. It can be managed, either with ongoing monitoring, and/or medications. It is not something that automatically means you are going to die soon.”