The Turnstone: talking about vaccines #32
The Turnstone: talking about vaccines #32
Be kind to your liver (7 minute read)
The liver
As long as it keeps on working, the liver is an organ that most of us probably think about very little. But it is actually an extraordinary organ. It has a number of completely different functions, such as filtering toxins from the blood, storing sugars and making bile, which helps us to digest fat. But it is also the only solid organ in the body capable of almost complete regeneration.
So, before I continue with today’s topic, which is Hepatitis B vaccination, I’m going to share a couple of resources about the wonderful liver.
Video about the functions of the liver (3 minute video)
What does the liver do? - Emma Bryce - YouTube
Article about liver regeneration (11 minute read)
Why Is the Liver So Amazing? · Frontiers for Young Minds (frontiersin.org)
Hepatitis
The term “hepatitis” refers to inflammation of the liver, which can have a number of different causes. One common cause is a virus, or rather a number of different viruses, creatively named hepatitis A, B, C, D and E. The viruses are unrelated to each other and each virus is different in its transmission and effect on the body. I will share resources about each of the viruses, as well the vaccines, which are widely available only for hepatitis A and hepatitis B.
The viruses
Hepatitis A
Hepatitis A has been in the New Zealand news recently, as there were a number of cases associated with imported frozen berries. Here are a couple of links with information about the outbreak.
Ministry of Health updates on the outbreak associated with frozen berries (3 minute read).
Hepatitis A and frozen berries | Ministry of Health NZ
Ministry for Primary Industries advice on the risk associated with frozen berries (2 minute read)
Risk of Hepatitis A from frozen berries | NZ Government (mpi.govt.nz)
A news item which includes an interview with someone who caught hepatitis A (4 minute read, 4 minute audio)
Victim of Hep A from imported frozen berries describes ordeal | RNZ
The hepatitis A virus is spread by food and water contaminated with human waste. It is common in countries which have poor sanitation, but is rare in New Zealand and other countries with good water and sewage treatment. A crucial point about transmission is the long incubation period of the virus – it can take 2-7 weeks for someone to show symptoms – and the fact that people are infectious for at least two weeks before they show symptoms. Usually, symptoms last 1-2 weeks, but the virus can cause serious illness and even death. However, it does not cause chronic infections.
Fact sheet from World Health Organisation (6 minute read)
General information with a New Zealand focus (7 minute read)
Hepatitis A | Health Navigator NZ
Hepatitis B
The hepatitis B virus is spread by contact with bodily fluids, in the same way as the HIV virus which causes AIDS. However, the hepatitis B virus is 50-100 times more infectious than HIV. In areas where the virus is common, it often passes from mother to child at birth, or is spread between young children. When babies and young children are infected, around 95% of the time they will go on to develop a chronic hepatitis B infection, which puts them at much greater risk of potentially fatal liver disease when they are older. In contrast, when adults are infected with the virus, they develop chronic infection only 5% of the time. This is why it is so crucial to protect babies and young children.
Of all the different hepatitis viruses, hepatitis B causes the greatest number of deaths around the world.
Fact sheet from World Health Organisation (7 minute read)
General information with a New Zealand focus (7 minute read)
Hepatitis B infection | Health Navigator NZ
Additional New Zealand information on chronic hepatitis B (5 minute read)
Chronic Hepatitis B | Health Navigator NZ
Hepatitis C
The hepatitis C virus is carried in the blood and is spread by contact with infected blood, for example by inadequate sterilisation of medical equipment or sharing needles for injected drugs. Most people have no symptoms at first, but around 70% of those who are infected go on to develop chronic infection. As with hepatitis B, people with chronic infections are at much higher risk of potentially fatal liver disease in the future.
Fact sheet from World Health Organisation (7 minute read)
General information with a New Zealand focus (6 minute read)
Hepatitis C (pokenga huaketo) | Health Navigator NZ
Hepatitis D
The hepatitis D virus is different from all the other hepatitis viruses. It cannot reproduce without the hepatitis B virus, even though the two viruses are not related. Because it can’t reproduce without hepatitis B, it only infects people who already have hepatitis B , or who are unlucky enough to be exposed to both viruses at once. It is mostly transmitted by contact with blood, and less commonly by other bodily fluids. Someone who is infected with hepatitis B and D is much more likely to develop severe liver disease than someone infected with hepatitis B alone.
Fact sheet from World Health Organisation (7 minute read)
Hepatitis E
The hepatitis E virus is like the hepatitis A virus – it is spread by food and water contaminated with human waste. Hepatitis E has a long incubation period, on average 5-6 weeks, and then it causes symptoms similar to those of hepatitis A. However, despite the similarities, the two viruses are not related.
Fact sheet from World Health Organisation (7 minute read)
Vaccines
There are widely available vaccines for hepatitis A and B, as well as a very new vaccine for hepatitis E.
Hepatitis A vaccines
There are vaccines available which protect against hepatitis A. In New Zealand, these are funded only for a limited group of people, such as transplant patients and children with chronic liver disease. The vaccines are also recommended for others at risk from hepatitis A, but in New Zealand these groups are not funded. Hepatitis A vaccination is also suggested for travellers in some regions of the world.
The hepatitis A vaccines are inactivated virus vaccines, which means they contain viruses which have had their genetic material destroyed so that they cannot infect cells. The following link has a video explaining the difference between live virus vaccines and inactivated virus vaccines, and why inactivated vaccines aren’t quite as effective as live vaccines.
How do inactivated vaccines work? | COVID-19 Info Vaccines (covid19infovaccines.com) (2 minute read and 5 minute video)
There are two different brands available in New Zealand, and there are also combination vaccines which protect against hepatitis A and either hepatitis B or typhoid. The first link gives you an overview of hepatitis A vaccines in New Zealand, including information on who is funded to receive the vaccine. The second and third links take you to the full information about the vaccines, on the Immunisation Advisory Service website. These links will take you to a summary but you can see more information by clicking where it says “in depth” and “datasheet”.
Hepatitis A vaccine | Health Navigator NZ (5 minute read)
Havrix | Immunisation Advisory Centre (immune.org.nz)
Avaxim | Immunisation Advisory Centre (immune.org.nz)
Here is information on hepatitis A vaccination for the USA (4 minute read).
Hepatitis A Vaccine Information Statement | CDC
Hepatitis B vaccines
There are vaccines available which protect against hepatitis B. These are protein subunit vaccines, the same type as the Novavax vaccine against Covid-19. Worldwide, the use of these vaccines has resulted in a decrease in both hepatitis B and hepatitis D.
Here is a video explaining how the Novavax vaccine is made and how it works (4 minute video).
How do protein-based vaccines work? | COVID-19 Info Vaccines (covid19infovaccines.com)
In New Zealand, the hepatitis B vaccine is part of the immunisation schedule for babies. It is also funded as a separate vaccine for some groups at higher risk, and recommended but not funded for some other groups. The first link gives you an overview of hepatitis B vaccines in New Zealand, including who is funded to receive the vaccine. The second and third links take you to the full information about the vaccines available on the Immunisation Advisory Service website. These links will take you to a summary but you can see more information by clicking where it says “in depth” and “datasheet”.
Hepatitis B vaccine | Health Navigator NZ (5 minute read)
Engerix-B | Immunisation Advisory Centre (immune.org.nz)
Vaccine for babies (given as a combination vaccine which also includes vaccines against other diseases)
Infanrix-hexa | Immunisation Advisory Centre (immune.org.nz)
Here is information on hepatitis B vaccination for the USA (4 minute read).
Hepatitis B Vaccine Information Statement | CDC
Other hepatitis viruses
According to the World Health Organisation, there are no effective vaccines available for hepatitis C. Hepatitis B vaccine protects against hepatitis D in those who are not already infected with either virus. However, once someone is infected with hepatitis B, there is no effective vaccine against hepatitis D. There is a hepatitis E vaccine available for use in outbreak situations, first used in South Sudan this year. See the following link for an article about it from Doctors Without Borders (4 minute read).
Once again, you've given me good information to think about - I've never thought of needing to get Hepatitis vaccines. My husband got vaccinated when he was a medical worker, and I think that one vaccination lasts for his lifetime? I'm not sure. But now I realize I don't know which hepatitis he was vaccinated against.
Thanks Heather. I hadn't thought about hepatitis vaccines much either until I saw it on New Zealand's vaccination schedule and thought I'd look into it. I was surprised how complicated it turned out to be.
It's not entirely clear how long the hepatitis vaccines last, but a single dose doesn't last too long. If I remember correctly from the information, with the full regime (usually 2 or 3 doses) then it's at least 10 years. With medical workers, it was probably hepatitis B, since that's a big risk with needle stick injuries and other contact with bodily fluids.