As part of our Vaccine Engagement Day campaign, we are sharing a series of blogs exploring vaccines, from major public health successes to future innovations. In our first post, we focus on vaccines that protect against chickenpox and shingles.
Chickenpox. We all know it. Statistically, you’ve had it. And you still do – technically, at least.
Varicella zoster virus causes both chickenpox (aka varicella) and shingles (aka herpes zoster). Found worldwide, varicella is extremely contagious and has been infecting humans for millions of years. Without vaccination programmes, the lifetime risk for infection is over 90%.
Unlike some viruses, varicella very rarely mutates. Compared to the flu, which gains around 40 new mutations every year, varicella is estimated to gain one new mutation every 200-400 years! This stability makes it an excellent target for vaccination. There is only one known version of the virus, and it does not naturally infect animals or insects. In theory, widespread vaccination could significantly reduce its circulation.
Understanding chickenpox: infection, symptoms and risks
While more common in children, anyone can catch chickenpox, and symptoms are often worse for adults. The characteristic rash usually develops a few weeks after the infection begins, and can appear anywhere on the body. After a few days, the itchy rash develops into small, fluid-filled blisters that scab over. Chickenpox can spread before the rash appears and remains infectious until all blisters have healed - the fluid in the blisters contains live viruses that can spread if the blisters burst. Other routes of infection include coughs and sneezes from infected people, and you can catch chickenpox from someone with shingles if you’ve never chickenpox before.
In most cases, chickenpox resolves on its own. However, it can become serious, especially for babies, pregnant people, and those with weakened immune systems. Complications can include bacterial infections following scratching (which can leave the skin open to bacterial infections), pneumonia, hepatitis, and in rare cases, inflammation of the brain, stroke or seizures. If someone is pregnant when they get infected, it can cause birth defects and even miscarriages. Before vaccination in the United States (US), chickenpox caused over 10,000 hospitalisations and more than 100 deaths each year.
Pox parties
Because chickenpox was so widespread, catching it used to be considered a normal part of childhood. Some parents even even intentionally exposed children to infection in so called “pox parties”, hoping they would “get it over with” early.
We now understand much more about the risks - there’s no way to know who might develop serious complications from infection, and what the long-lasting impact of those complications might be. Today, intentional exposure to infectious diseases is strongly discouraged, and the best way to protect against chickenpox is vaccination.
The chickenpox vaccine
Chickenpox (and by extension, shingles) is a vaccine-preventable disease.
Varicella vaccines were first developed in the 1970s in Japan and have been used in Europe since the 1980s. In the early 2000s, varicella vaccines were combined with other vaccines, including the MMRV vaccine, which protects against measles, mumps, rubella, and varicella, and has been shown to provide around 95% protection against chickenpox for more than a decade post-vaccination.
The vaccine is given in two doses, with the first generating protection, and the second enhancing and prolonging that protection. Numerous studies over several decades have shown the safety and effectiveness of varicella vaccines, with a 2019 report showing serious side effects occurred in only 0.8 doses per million given (0.00008% of doses).
The vaccine is a live attenuated vaccine, meaning it contains a weakened version of the varicella virus that the immune system can recognise and respond to without causing disease. The vaccines used today are based on the very first, developed in Japan by Michiaki Takahashi (and colleagues) in the early 1970s, using a weakened version of varicella called the ‘Oka’ strain. If a vaccinated person later encounters varicella, immune memory helps prevent infection or reduce its severity.
From January 2026, vaccination against chickenpox has been introduced as part of the routine childhood schedule in the UK in the form of the MMRV vaccine. MMRV has been used for over a decade in countries like Canada, Australia, and Germany with strong results. In the US alone, varicella vaccination has prevented over 90 million cases in just 25 years, and is estimated to have saved the lives of around 2,000 people. Vaccination against chickenpox has also been shown to decrease the number of shingles cases.
Take a look at our guide to childhood vaccinations to understand how vaccines work and the vaccination schedule for children, including MMRV. Adults can also receive the vaccine based on their risk of catching or transmitting the disease – contact your GP to see if you’re eligible.
What’s the difference between chickenpox and shingles?
Chickenpox and shingles are both caused by the varicella virus. For many years, the two conditions were thought to be separate. It was only in the mid-20th century that researchers, including Thomas Huckle Weller, showed that the varicella zoster virus could be isolated from both chickenpox and shingles, revealing that they are two stages of the same infection.
The difference depends on if this is your first time encountering the virus. If it is, you’ve got chickenpox. After chickenpox, the virus does not leave the body. Instead, it becomes dormant in nerve cells, sometimes for decades. Later in life, it can reactivate as shingles.
Shingles vaccination: protecting health later in life
Around 1 in 4 adults will develop shingles (herpes zoster) during their lifetime, most commonly in people over 50 or those with weakened immune systems. While shingles often has no clear cause, factors like stress, illness, or medicines that suppress the immune system can increase the likelihood of the virus reactivating.
One reason shingles becomes more common with age lies in how our immune system changes over time. Protection against the varicella zoster virus relies heavily on T cells, and as we get older, this T cell response gradually weakens.
Recognising shingles and its complications
Unlike chickenpox, shingles usually affects a specific area of the body. Early symptoms often begin with burning, stabbing, or tingling pain in a localised band across the body, face or neck. This occurs because the reactivated virus travels along a nerve to the skin, then causing the blistering rash8 - which was discovered in a landmark study led by Dr. Donald Gilden in 1983 (and subsequent studies by his group), which proved that varicella zoster virus DNA lies present in the sensory ganglia of humans.
Usually, it takes up to 4 weeks for the rash to heal and most people recover without any complications. However, some people experience skin infections, scarring, muscle weakness, vision loss, or a rare condition called Ramsay Hunt syndrome, where shingles affects the facial nerve and can cause facial weakness and hearing problems.
One of the most common complications is post-herpetic neuralgia (PHN), where severe nerve pain continues for up to 6 months after the rash has disappeared. This persistent pain can be debilitating and may affect everyday activities, like dressing and cooking/eating, significantly reducing quality of life. PHN has also been linked to depression, anxiety, sleeplessness, and weight loss. For older adults, these complications can have an even greater impact, particularly for those already living with other health conditions or reduced mobility.
Shingles itself is not contagious. However, because it is caused by the same virus as chickenpox, someone with shingles can pass the virus to people who have never had the infection or the vaccine. For this reason, it’s best to avoid close contact with certain groups while you have shingles, including pregnant people who have never had chickenpox, people with weakened immune systems, and babies younger than one month.
The introduction of shingles vaccination in the UK
For much of history, shingles was largely managed after it occurred, rather than prevented. This began to change in the UK in 2013, when a national shingles immunisation programme was introduced for adults aged 70, with a phased catch-up programme for those aged 71-79. The programme initially used a single dose of the live attenuated vaccine Zostavax®.
Even with moderate uptake, early evaluations demonstrated clear benefits. Within the first five years of vaccination in England, it was estimated that around 40,500 GP consultations and 1,840 hospitalisations related to shingles were prevented among adults aged 70-79 years. The vaccine was also shown to reduce the risk of PHN, one of the most debilitating shingles complications.
Newer vaccines and stronger protection
From September 2023, the UK shingles vaccination programme began transitioning from Zostavax® to a newer vaccine, Shingrix®, which provides higher and longer lasting protection. Clinical studies have shown that Shingrix® is around 97% effective in adults over 50 years of age, and 91% effective in adults over 70 years, providing strong protection against shingles and its complications.
Preventing shingles has important benefits beyond avoiding the rash itself. Severe pain, complications like PHN, and hospitalisation can place significant strain on individuals, families, and the NHS. In England alone, before widespread vaccination, shingles accounted for an estimated 41,780 hospital days each year, costing the healthcare system around £13 million annually.
Take a look at our guide to vaccinations for adults over 65 to learn more about eligibility and protection later in life.
Together with childhood vaccination against chickenpox, the shingles vaccine demonstrates how immunisation can protect people at different stages of life. By reducing both the risk of infection and the complications that follow, they offer another powerful example of why there is so much reason to #CelebrateVaccines.
By Ellie Pearson, External Affairs Intern and Madeline Crouch, Marketing and Communications Officer