The UK routine varicella vaccination programme, announced on the recommendation of the Joint Committee on Vaccination and Immunisation and now being rolled out through primary care and community pharmacy, has changed the shape of paediatric counter conversations. Parents who barely thought about chickenpox a year ago now want to know what is on offer, who gets it free, what it costs privately, and whether it clashes with anything else in the schedule.

This is a clinical decision-tree for the prescribing professional — community pharmacist prescribers, practice nurses and GPs delivering childhood vaccination — based on the Green Book, the UKHSA routine immunisation schedule and the summaries of product characteristics for Varilrix and Varivax. It is not a replacement for the full Green Book chapter, which remains the authoritative source.

The scheduling framework

The UK programme uses a two-dose varicella schedule. Eligible children are offered:

• First dose at 12 months of age, co-administered with MMR (as separate injections).
• Second dose at around 3 years 4 months of age, co-administered with the routine MMR second dose.

The two-dose schedule is preferred to single-dose because of the well-described phenomenon of breakthrough varicella after one dose — milder than wild-type chickenpox but still capable of transmission. A two-dose programme produces substantially higher seroprotection at the population level.

Products used in the UK are the live attenuated vaccines Varilrix (GSK) and Varivax (MSD), both based on the Oka strain. The two products are interchangeable where supply and clinical judgement require.

The UK routine immunisation schedule and Green Book Chapter 34 document the programme specifications as they evolve; prescribers should check the current version of both.

Catch-up cohorts

Catch-up is a clinical judgement informed by UKHSA guidance as the programme beds in. At the time of writing, the framework is:

• Children who missed the routine 12-month dose can receive catch-up at any time up to their pre-school booster appointment.
• Second doses can be brought forward where there is a household or outbreak exposure, provided the interval since the first dose is at least 4 weeks (Varilrix) or 3 months (Varivax), per the SmPC.
• Older children up to age 12 without evidence of past infection or vaccination can receive two doses at least 4 weeks apart.
• Adolescents aged 13 and older follow an adult-style two-dose schedule with a longer interval, and should have serological confirmation of non-immunity if clinically uncertain.

Contraindications and precautions

Varicella vaccine is a live attenuated vaccine. Standard live-vaccine contraindications apply.

Absolute contraindications:

• Known severe immunodeficiency — congenital, HIV with low CD4, on high-dose systemic steroids, on biologic therapy, recent haematopoietic stem cell transplant within specified window.
• History of anaphylaxis to a previous dose, gelatin or neomycin.
• Pregnancy (see below).

Precautions — defer rather than omit:

• Moderate or severe acute illness with fever.
• Recent receipt of blood products or immunoglobulin within the past 3–11 months, depending on product and dose (see Green Book Chapter 34 table).
• Children on salicylates (aspirin) — theoretical risk of Reye syndrome; avoid salicylates for 6 weeks after vaccination.
• Recent anti-varicella antiviral therapy — defer for 24 hours post-aciclovir, and ensure the child is not taking aciclovir during the two weeks after vaccination unless clinically necessary.

Household immunocompromise: a common counter question. Varicella vaccine virus transmission from a healthy vaccinee to a household contact is rare — case reports exist, typically only when the vaccinee develops a post-vaccination rash. The Green Book position is that vaccination of a healthy household contact of an immunocompromised individual is encouraged, because the risk of wild-type varicella transmission is substantially higher than the risk of vaccine-strain transmission. Advise parents to avoid contact between any post-vaccination rash and the immunocompromised household member until the rash resolves.

Concurrent-vaccine spacing

Live vaccines follow a two-rule principle:

1. Live vaccines can be given on the same day without restriction — MMR and varicella on the same visit are both licensed and recommended.
2. If two live parenteral vaccines are not given on the same day, they should be separated by at least 4 weeks. This applies to MMR and varicella, MMR and yellow fever, and so on.

Practical counter scenarios:

• MMR and varicella on the same day → both in, different limbs, no issue.
• MMR given last week, varicella this week → defer varicella to at least 4 weeks after MMR.
• Varicella given and parent asks about BCG or yellow fever → separate by 4 weeks.
• Inactivated vaccines (e.g. DTaP/IPV/Hib/HepB, rotavirus oral, MenB, PCV, 6-in-1) do not require 4-week separation from varicella. Give at the appointment that suits the child, observing product-specific co-administration data.

A small number of parents will request a standalone varicella appointment separated from MMR on preference grounds. Where local scheduling permits, this is reasonable provided the minimum 4-week interval between live vaccines is respected.

Pregnancy, fertility and adolescent girls

Pregnant women should not receive the varicella vaccine. Women of childbearing potential should be counselled to avoid pregnancy for 1 month after each dose. In practice, inadvertent vaccination in early pregnancy has not been associated with congenital varicella syndrome in follow-up cohorts, but the precautionary recommendation remains.

Breastfeeding is not a contraindication.

Side effects parents ask about

• Local reaction (redness, swelling, soreness) in 20–30% of children; self-limiting.
• Fever in 10–15%, usually within 2 weeks of dosing.
• Injection-site rash in a small proportion.
• Generalised varicella-like rash — typically a few spots, mild, 7–21 days after vaccination. Cover the spots if present; avoid contact with immunocompromised individuals until resolution.
• Febrile convulsion — a small increased risk in the 7–14 days after MMR-containing vaccines, particularly with MMRV combination products, which is one reason the UK programme favours separate MMR and varicella injections rather than a combined MMRV formulation for the first dose in this age group.

Counselling points for the pharmacy counter

1. Two doses. The first at 12 months, the second at the pre-school booster. Both matter.
2. Same day as MMR is fine and is the NHS approach.
3. Side effects are mild and self-limiting.
4. No contact with newborns, pregnant women or immunocompromised household members if a post-vaccination rash develops.
5. No aspirin for 6 weeks post-dose.
6. Wild-type chickenpox is usually mild but can cause serious complications — bacterial superinfection, pneumonia, encephalitis — which is why the UK programme has moved forward.

Further reading on PharmSee

• Chickenpox vaccine: UKHSA programme FAQ
• Chickenpox: pharmacy options for children
• Pharmacy travel health vaccinations

Find a UK community pharmacy on PharmSee.

Sources and caveats

Content drawn from Green Book Chapter 34 (Varicella), the UK complete routine immunisation schedule, NHS patient information and the BNF. Programme specifications evolve; prescribers should check the current Green Book and UKHSA guidance before each session. This article is a clinical reference for UK prescribing professionals, not a substitute for the Green Book chapter or the product SmPC.