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Your guide to varicella / chickenpox vaccination in the UK

We have a whole list of routine vaccinations for diseases that most of us wouldn’t dream of suffering nowadays: tetanus, diptheria, polio, and pneumococcal disease to name a few. That doesn’t mean that the list is complete though. There’s no real reason for anyone and especially not children to suffer or be endangered by diseases that can be safely and easily prevented. If we compare the UK immunisation schedule to that of the US, Canada, Australia, Germany, South Korea, Latvia, QatarCosta Rica, Ecuador, Uruguay, Mexico and other countries, as well as to the WHO List of Essential Medicines  we see a glaring omission in our schedule: chickenpox.

So what’s the deal with the chickenpox vaccine, how has it worked where it’s been deployed, and why don’t we have it here? Let’s find out.

This is going to be long, so you can flip around between sections here:

Background to the disease & vaccine:
Chickenpox and shingles have been known to humanity since ancient times and chickenpox especially is a familiar name in any household with small children. It has an incubation period of 10-21 days and is recognisable by its itchy rash. It’s usually a mild illness but in some patients there are serious side effects, which can include cellulitis, haemorrhage, encephalitis, pneumonia, and hepatitis, among others.1)

Varicella, or chickenpox, was first suggested to be linked with herpes zoster, or shingles, in 1888 and the relationship was proven in the 1950s when the underlying virus was identified and named as varicella zoster virus (VZV). The genome was sequenced in 1986.2)

There have been efforts since the 19th century to create some sort of vaccine, though they were unsuccessful, so interest in preventing the pox is not recent.  The vaccine was developed in Japan and was completed in 1974.3)

But chickenpox is a mild childhood illness! Well, that’s not really true. On average every year in the UK 25 people die of this disease, that’s more than from measles, mumps, pertussis, and Hib meningitis combined (at the time of article).4)

Possible complications include bacterial skin infections, sepsis (blood infection), encephalitis, pneumonia, toxic shock syndrome, nectrotising fasciitis, and other severe illnesses.5)

Studies have found that most deaths from chickenpox were not in a high risk category though immunocompromised people and those with underlying health issues are at serious risk. Of course this makes sense because there are more people who are non-immunocompromised than those who are, but it dispels the belief that only people with serious health complications are at risk of negative outcomes.7) In fact one of the most convincing reasons to consider routine vaccination against chickenpox is the huge benefit to healthy children10) and in Germany a study found that the severity of complications in otherwise healthy children has been underestimated.11)

So, we know that the disease is usually relatively mild but can be very serious and that there’s not really any way to predict who will be hit hard and who won’t be. The vaccine has been around for quite a long time and is in routine use all around the world and supported by the WHO, who take an evidence-based approach to other issues many of us care a lot about including breastfeeding and improving infant medical care. What have the results of the vaccine programs been like in other countries, though? Read on.

Introduction of the vaccine around the world

In 1995 the vaccine was introduced in the United States CDC’s immunisation schedule for the first time12) Originally given as a single dose, a significant level of protection was conferred, but studies began to find that it was not enough and there were still breakthrough infections.13) The decision was taken in 2006 to move chickenpox vaccination to be in line with other vaccinations and they began to recommend a booster14)


In the first 10 years of the US vaccination program, even with only one dose of the vaccine, chickenpox was nearly eliminated. In the first 12 years of the program deaths due to chickenpox decreased by 88%, and for those under 20 years old the decrease was 97%.15)

In that same period, there was a huge amount of research generated and a meta-analysis concludes that one dose was 84.5% effective at preventing chickenpox and 100% effective at preventing severe cases, with the expectation that the two dose scheme would change that even further.16)

In 2003 the government of Sicily rolled out the vaccine to all local health units there as part of the immunisation schedule. Within four years the rate of chickenpox incidence dropped from 95.7% to 9%, and that with only the single dose of the vaccine, as was the guidance at the time, with 87.5% of the measured birth cohort taking the vaccine.18) With two doses of the vaccine and full uptake the effect could be even greater, and will be as it is rolled out to more birth cohorts over time.  The early results of introduction of the single dose of the vaccine in Australia led to a significant decrease in hospitalisations, with the greatest decrease among children of 18-59 months, again based on the single vaccine.19)

Germany introduced the chickenpox vaccine into their immunisation schedule 11 years after the US, in 2006. Their main goal was to simply reduce the number of infections as well as to reduce cost of treating the disease, complications, and hospitalisation20)

Preliminary results within three years of introduction were a 55% reduction of chickenpox across all age groups, and 63% in 0-4 year olds.23) This result is lower than in other countries, but bear in mind that this was based on the single dose immunisation scheme, that no catchup vaccination for older children was offered, and that Germany has one the lowest immunisation rates in Europe24), so it is a strong result, all things considered. In 2009 the German schedule was updated to reflect research and introduced the second dose.25) A more detailed, more recent study found a 67% reduction in cases and hospitalisations in young children also decreased, even with continued comparatively low vaccination rates.27)

Therefore, we know that the vaccine is highly effective in reducing incidence of cases and the number of resulting complications.

However, people often worry about the safety of vaccines they’re not familiar with, or new vaccines. As mentioned above, this is not a new vaccine – it was developed over 40 years ago, has been in routine use in the US for 20 years and implemented in numerous other countries in the intervening years. This means that we have an excellent window of time over which to view how safe this vaccine is.

Of the 50 million doses distributed in the US over the first ten years, there was a rate of 53 reports of complication per 100,000 doses.28) Bear in mind that that includes side effects like rash and soreness at injection site – minor in comparison to the symptoms of even a mild case of chickenpox. Out of the 50 million doses in that period there have been only a few confirmed cases of pneumonia, severe rash, hepatitis, and shingles with meningitis. This is significantly lower than the rates of complication from wild chickenpox.29) This also includes cases where it turned out that the child has serious health problems that the doctor had not diagnosed prior to vaccination – presumably in these cases wild chicken pox could also cause them serious health issues.


Secondary transmission of chickenpox via the vaccine, or shedding, is sometimes held up as a concern. If you read package inserts they will usually mention this as a possibility and even the CDC mentions in passing that it’s possible.30) In reality this is legalese and technical language.

There are, at the time of writing this, 7 known cases32) believed to be from derived from secondary transmission, or shedding, out of the tens of millions of doses distributed around the world. Or to put it another way: many, many, many times less likely than being hit by lightning, which is not something most people plan their lives around.

These cases are so rare that they are documented in detail in peer-reviewed journals as fascinating case studies because of how uncommon they are.33) In the cases cited, the secondary cases were mild, though of course with only a handful of cases it’s impossible to say that that’s because they only caught a weakened form of the virus.  In fact, in the Japanese case cited above, the girl had already been vaccinated, making it a particularly odd incident.

Post-vaccine exposure to pregnant women

Shedding as a risk is sometimes brought up in the context of a pregnant woman being around recently vaccinated children. If shedding were a significant risk, this would indeed be a concern. However, given the incredibly low rates of secondary transmission, it seems like it should be more of a concern that the woman’s child will catch wild chickenpox and the mother will catch that, given how common chickenpox still is in the UK. In fact, only one case is documented of a pregnant mother catching chickenpox from her vaccinated child, and in that case no virus was detected in the foetus.35)

In cases where women didn’t know they were pregnant but were vaccinated against chickenpox, contrary to the legal warnings, there is no actual evidence of any harm. Indeed, a 2008 study found that over ten years of study there was no evidence for congenital varicella syndrome and varicella vaccine exposure.36) Of course it’s prudent to take a cautious approach, but the evidence suggests that the vaccine is ever safer than we realise.

Post-vaccine exposure to immunocompromised people

Package inserts also warn patients to avoid immunocompromised people, but with so incredibly few examples of shedding and such a risk of non-immunocompromised children catching chickenpox, this is questionable advice. A small study from the first years of the vaccine’s licenciature in the US found no cases of the vaccinated person transmitting the disease to the immunocompromised household member37) and in fact the US guidelines recommend that some immunocompromised patients actually receive the vaccination, including those suffering from certain forms of HIV38) and a very early pre-licenciature study found it safe to use for children with leukaemia in remission.39)

Another question is how long the chickenpox vaccine is effective for. So far, based on the time period we have available to study, the picture is quite good. Studies show a 10-20 year period of protection – that would be how long we have available to study, but the length of protection could be much higher as live vaccines typically confer long-lasting protection40) and studies have found that after two doses of the vaccine patients show similar titre levels similar to those of people who have had wild chickenpox.41) It’s also worth considering that once a routine vaccination scheme is implemented, this is less relevant because the disease won’t be circulating and exposure is highly limited.

Cost benefit

Of course, all of this costs money for a health care system to put into place. A lot of people feel that chickenpox is a mild illness and that adding the cost of the vaccine is more than the system can take. Well, that’s not really true. Aside from the ethical decision to take action to prevent deaths, there is of course the direct cost of purchasing and distributing the vaccine. However, there is also the reduction of costs from hospitalisations, medication for complications, aftercare, and the secondary costs of lost productivity because people need to miss work because either they are sick or their kids are. A German study found considerable cost benefit when looking at that total picture42) and a Singaporean43) and Canadian study found the same.44) A relatively recent review of the research found that when indirect costs are taken into account and possible negative effects relating to shingles are not included (dismissed as linked with plenty of evidence down the page here) “routine early-childhood vaccination programs are always cost saving”45) Another review found no net savings46) however, as other studies pointed out the the indirect benefits are understated in most research.

So it seems that, at best it is a savings across society, and at worst it’s not but still saves lives. Hard to lose, really.


Why the vaccine isn’t yet available in the UK & the disproven shingles link

I hope you’re thinking at this point that this sounds like a great deal. A disease that is usually not so bad but can be unpredictably fatal, is usually pretty miserable, and can cause some nasty scarring, and it can be prevented by two doses of a safe and effective vaccine and if most people take the vaccine the disease can be essentially eliminated! What’s the catch? Why don’t we have this in the UK?

The NHS has been very cautious in taking up a vaccine that has been around for over forty years, in spite of inclusion on the WHO list of essential medicines and nearly twenty years of solid history in multiple countries of benefits of broad scale rollout. First of all, as this BBC article points out, all discussion of vaccines takes place in the shadow of Andrew Wakefield’s totally discredited claims that the MMR vaccine causes autism. It’s impossible to step out of that shadow.

The shingles claims

But from a medical standpoint, you might have read some of the discussion here. The hesitation is based on the following.

In 1965 it was theorised that periodic exposure of adults who have already had chickenpox to cases of active chicken pox will protect them against reactivation of varicella zoster virus in the form of shingles47) and that has been supported by evidence.48) Several studies predicted or expressed concern that since routine vaccination would result in less chickenpox circulating in the population, there would be less exposure of adults to chickenpox, and therefore an increase of shingles cases.49) Since shingles is a disease with a higher morbidity rate than chickenpox this risk was deemed unacceptable in the UK.51)

But this hasn’t turned out to be the case and the research has decisively shut down this concern about vaccination.

A study looking at 16 years’ worth of data in Alberta found that shingles was on the rise before vaccination and therefore routine vaccination has not led to the increase of shingles.52) Two US studies found that variability in vaccination rates between states did not affect shingles rates.53) Another US study, covering 13 years of data, also found no effect of mass vaccination on shingles rates.55) A ten year study again found the same result.56) A study of 18 years of US Medicare claims found no link as well.57) A good discussion by epidemiologist Dr Craig Hales can be found here.

So that can be clearly put to rest as a reason to not introduce the vaccine.

In any case, even though this theory has been debunked, there is another reason why shingles should not interfere with routine childhood immunisation against chickenpox.  The rollout of a shingles vaccine for elderly adults has begun in the UK58), which will offer significant protection until such time as the adult population will have grown up without having suffered through chickenpox and most people won’t have been infected with the wild virus. So the shingles vaccine only needs to be a (relatively) short term solution, and ideally the same would hold for the chickenpox vaccine. If the disease was eradicated – as happened with smallpox – we could stop vaccinating.

It’s also worth noting that anti-vaccination lobbyists often argue against the chickenpox vaccination based on both the shedding and the shingles claims. In reality, if the vaccine was transmissible by shedding and if the shingles risk was real, then the shedding of the vaccine from vaccinated individuals would protect the older population against shingles, which conflicts with the claim that shingles is in fact increased by routine childhood vaccination. Neither argument is valid.


But we have to look at the cost and benefit. Up the page we looked at the cost benefit of routine vaccination to society. What is the actual direct cost, though?

In the 2015 British National Formulary for Children – the official guide to all medications available in the UK – listed the VZV vaccine at £27.31 or £30.21 per dose depending on the brand.59)

That is quite high, though many people pay that plus a huge retail markup today to get the vaccine administered privately. The cost to the NHS would not be anywhere near that once they buy in mass quantities. By way of comparison, the MMR vaccine is £7.64.60)

However, it’s important to remember that if rolled out it would probably be included as part of the MMRV tetravalent (four virus) vaccine, which is significantly cheaper than the standalone. This means a more cost-effective delivery of all four vaccines.

It’s worth mentioning a study that specifically discusses cost savings in England and Wales.61) The study at this point can be put aside as a point against routine chickenpox vaccination. There are several reasons for this, including that it assumes that shingles will rise as a result of routine vaccination of children. We know now that is not the case. It is based on a price that would not be correct if purchased en masse, when various cost-benefit studies specifically mention that the price is an important factor in determining the benefit62) Many assumptions were made about work loss, and household costs were based on North American figures.


Chickenpox is usually mild with no long-lasting effects, but for a certain proportion of people it’s severely harmful or even fatal and that is not limited to the immunocompromised or otherwise ill. There is a vaccine available, but it is not currently available on the NHS; however, word is that it will come soon. If you want to get the vaccine privately in the UK you can go to a private GP, a travel clinic, or another vaccination clinic that offers the vaccine. You can search for a local clinic here.

Citations   [ + ]

1, 5.
2, 3.
7, 15.
22, 42.
23, 25.

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