The Turnstone: talking about vaccines #29

Chickenpox and shingles (5 minute read)

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When we talk about an illness like COVID-19, we are often casual in how we use words like disease and virus, sometimes using them as if they are interchangeable. However, there are important distinctions – officially, for example, COVID-19 is the name of a disease, while the virus which causes the disease has the name SARS-CoV-2.

This month, I’m talking about two different diseases, and the virus which causes both, so the distinction is important. The virus is called varicella zoster virus, and you’ve probably never heard of it. However, the two diseases caused by this virus, chickenpox and shingles, will be familiar, perhaps painfully so.

Even though they are caused by the same virus, chickenpox and shingles are two different diseases. They have different symptoms and they affect different groups of people. But there are vaccines available which protect against both diseases. I have put together resources to help you understand both diseases and their vaccines.

Chickenpox – the disease

Chickenpox is the name given to the disease caused by the varicella zoster virus when the infected person has caught the virus from someone else. Confusingly, the disease chickenpox is sometimes known by the name varicella. Even more confusingly, it has nothing to do with chickens and it is not a pox virus, that is, it’s no relation of smallpox, monkeypox, cowpox and camelpox. The internet is full of theories about the origin of the name, although I’ve found nothing authoritative.

The virus which causes chickenpox is highly contagious, causing fever and an itchy rash which can affect the whole body. Mostly it doesn’t cause serious problems, although the itching can be miserable and lead to infections as a result of scratching. Sometimes, chickenpox can result in permanent scars. However, in some cases it can be a serious disease. It is particularly dangerous in pregnant women, young babies and those with weakened immune systems.

Here is some basic information on chickenpox from the National Health Service in Britain (5 minute read).

Chickenpox - NHS (www.nhs.uk)

Here is some slightly more detailed information from New Zealand’s Immunisation Advisory Centre (6 minute read)

Varicella (chickenpox) | Immunisation Advisory Centre (immune.org.nz)

Chickenpox rash (image credit: CDC/ K.L. Herrmann)

Shingles – the disease

Usually, when we recover from a disease caused by a virus, the virus is gone from our body, but chickenpox is different. When we recover from chickenpox, the virus hides in our body, in nerves near the spine. Most of the time, it is kept under control by our immune system, but if our immune system is weakened, the virus can cause disease again. This disease is known as shingles (also known as herpes-zoster).

Shingles most often affects those over 50 or those with a weakened immune system, for example as a result of cancer treatment. Its most notable feature is a rash which affects only one side of the body, usually in a confined area (as opposed to chickenpox, which affects the whole body). I’ve been lucky enough to escape it so far, but I’ve been told that it’s particularly painful, as opposed to the rash from chickenpox, which is itchy. Around one in five people who get shingles then develop a painful condition called post-herpetic neuralgia, which is a lasting nerve pain. The risk of developing this condition increases as you get older.

If someone with shingles comes into contact with someone who has never had chickenpox, they can pass on the virus which causes both diseases. In particular, this is a risk to babies who are too young to be vaccinated – so take care if you do get shingles.

Here’s some basic information about shingles (4 minute read)

Herpes zoster (shingles) | Immunisation Advisory Centre (immune.org.nz)

The following link has good information about post-herpetic neuralgia (4 minute read)

Shingles (mate huaketo hei) | Health Navigator NZ

Vaccines

Now, here is where things might get a bit more confusing. In New Zealand, there are three vaccines available against the varicella zoster virus, and the picture is probably similar overseas, depending on where you are.

First, there is the chickenpox vaccine, which has the name Varilrix. In New Zealand, this is given as a single dose to children aged 15 months. This is a live virus vaccine (like the measles vaccine and the oral polio vaccine), which comes with benefits and risks. It’s very effective, but it can’t be given to those with a weakened immune system.

Here’s some basic information from the New Zealand Ministry of Health about Varilrix. The link may take you to the chickenpox summary page, but there’s a blue box with the word “prevention” – if you click on that you’ll be taken to the vaccine information (3 minute read).

Chickenpox | Ministry of Health NZ

There are also two vaccines available which can prevent, or at least reduce the severity of, shingles.

In New Zealand, you can get a free shingles vaccine if you are 65 or over. The vaccine is also available for those aged 50-64, but you have to pay, and it costs hundreds of dollars.

If you get a shingles vaccine right now, it’s not certain which of the two vaccines you will be given. That’s because New Zealand is currently changing over from one type of vaccine to another. Until the end of July 2022, the vaccine which was funded for those 65 and over was Zostavax. This is a live virus vaccine, and like the chickenpox vaccine it can’t be given to those with weakened immune systems. From the start of August, the funded vaccine is Shingrix. This is the same type of vaccine as the Novavax vaccine for COVID-19, known as a recombinant subunit vaccine. The vaccine contains no live virus, just fragments of the coat protein. This means it is safe for those with weakened immune systems.

The following site has a good comparison of the two vaccines (3 minute read).

Shingles vaccine | Health Navigator NZ

The following page, from the Oxford Vaccine Group, gives more detailed information about Zostavax, with a smaller amount about Shingrix (7 minute read).

Shingles Vaccine | Vaccine Knowledge (ox.ac.uk)

The following page, from the US Centres for Disease Control gives more detailed information about Shingrix (6 minute read)

Shingles Vaccination: What Everyone Should Know | CDC

For more information

Here is a good summary of the differences between chickenpox, shingles, and their vaccines. It’s very useful although it does have a USA perspective (2 minute read).

Chickenpox versus shingles—What’s the difference? - APIC

Finally, here’s a fascinating, plain English article from a microbiologist which looks at the science of chickenpox and shingles in more depth (7 minute read)

The chickenpox virus has a fascinating evolutionary history that continues to affect peoples' health today (theconversation.com)

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