_ RCGP Learning

Written by Dr Toni Hazell

Chickenpox is a common and unpleasant childhood illness. More than 90% of the population have acquired antibodies to the causative infection (the varicella zoster virus) by the age of 15¹. For many it is a self-limiting illness (often leaving behind scars when scratching cannot be resisted), but there is a risk of significant complications, as listed in the box below. Those at a higher risk of complications include adults, adolescents, children aged under one, pregnant women and immunocompromised people. Around 20 people per year die of chickenpox in the UK³ and there is a risk of neonatal death if a susceptible woman contracts chickenpox in the week before delivery³.

The economic cost to the UK of parents taking time off work to provide childcare to their children with chickenpox is estimated to be over £24 million per year⁴ – the difficulties of taking prolonged time off work for childcare perhaps explains why one survey (the satisfyingly named SPOTTY study⁵ showed that 73% of UK paediatricians surveyed had privately vaccinated their child against varicella. As the author of this blog discovered last year, chickenpox can also wreak havoc if it appears two days before a family holiday!

Until recently, NHS chickenpox vaccination has only been offered to a small group of people. These include susceptible healthcare staff (including non-clinical, e.g. cleaners, porters etc), laboratory staff who work with the varicella virus, and close household contacts of immunocompromised patients, such as siblings of a child with leukaemia, or a child whose parent is having chemotherapy³. For patients who are due to start immunocompromising medication and are susceptible to varicella, vaccination is offered if there is enough time to give the two-dose course before the medication has to be started³.

This will change in January 2026, when universal vaccination begins on the NHS in all four countries of the UK ^6,7,8,9. Details of the programme are as follows¹⁰

• Offered to children at the age of 18 months.
• Given with measles, mumps and rubella as the MMRV vaccine.
• Booster at three years and four months of age.
• One-dose catch-up programme for children born between 1.1.2020 and 31.8.22, who can access the vaccine until the end of March 2028.
• No NHS offer of a single varicella vaccine.
• The MMR vaccine without varicella will no longer be available for the NHS routine childhood immunisation programme, although it will still be available for those who need the MMR vaccine in adulthood. Children who did not have MMR at the usual time and are brought later in childhood should be caught up with MMRV.

So why have the Joint Committee on Vaccination and Immunisation (JCVI), who decided against universal childhood varicella vaccination in 2009, changed their mind? The original decision was made on cost-effectiveness grounds, with an estimate that it would take 80-100 years for the programme to become cost-effective¹¹. The new decision has largely been based on two factors – a review of the prevalence of chickenpox complications, and a change in the way we think about shingles in adults.

The JCVI believe that the cost of chickenpox complications has probably been underestimated, affecting their assessment of of cost-effectiveness of the vaccine. It is likely that many people admitted with complications of chickenpox have had their admission coded with the name of the complication (pneumonia, meningitis, cellulitis etc) but that the code for chickenpox was not added, so the two weren’t linked for the purposes of cost calculation¹¹. The availability of the four-virus MMRV vaccine has also improved the cost-effectiveness calculation, as there is no need for another nurse appointment, over and above the one which would have been necessary for the MMR vaccine.

Another concern in 2009 was that vaccinating against chickenpox would put older adults at an increased risk of shingles, caused by reactivation of the varicella virus. The theory was that those who have had chickenpox in the past have their immunity regularly boosted by coming into contact with children who have varicella (which is infectious during the prodrome, before spots have appeared and children are kept at home) and that reducing chickenpox incidence in children would increase shingles in middle-aged adults. At the 2023 review it was clear that data from the United States (who have vaccinated against chickenpox since 1995) did not support this hypothesis11 – and we also now have the NHS shingles vaccination, which was not offered in 2009.

Vaccine hesitancy remains an issue in the UK, with only 85% of English 5 year olds having had two doses of MMR – uptake in some communities is significantly lower than that¹². It will be interesting to see whether the addition of varicella to the MMR vaccine reduces uptake further, due to unwarranted nerves about multiple vaccine, or whether the benefits of not having to look after an irritable child with chickenpox will encourage people to vaccinate, in turn increasing MMR uptake.

References

1. NICE CKS. Chickenpox. Nov 2023.
2. Oxford Vaccine Group. Chickenpox (varicella). Nov 2023.
3. UKHSA. Varicella: the green book, chapter 34. Sept 2024.
4. LSE. The true cost of chickenpox: at least £24 million in lost productivity a year in the UK. April 2022.
5. O'Mahony E, Sherman SM, Marlow R et al. UK paediatricians' attitudes towards the chicken pox vaccine: The SPOTTY study. Vaccine. 2024 Sep 17; 42 (22): 126199.
6. DHSC. Free chickenpox vaccination offered for first time to children. Aug 2025.
7. Department of health. Chickenpox vaccination to be offered to children in Northern Ireland from 2026. Aug 2025.
8. NHS Scotland. Changes to the Scottish Childhood Vaccination Schedule from 1 January 2026 (phase 2) – introduction of a routine Varicella Zoster (Chickenpox) vaccine. Nov 2025.
9. NHS Wales. New Chickenpox (Varicella) Vaccination Programme in Wales.
10. UKHSA and NHSE. Introduction of a routine varicella (MMRV) vaccination programme for children at one year and at 18 months. Oct 2025.
11. DHSC. JCVI statement on a childhood varicella (chickenpox) vaccination programme. Nov 2023.
12. UKHSA. Evaluating the impact of national and regional measles catch-up activity on MMR vaccine coverage in England, 2023 to 2024.Aug 2024.