Chickenpox vaccination service clinical update
- Estimated Time: 60 minutes.
- Difficulty: Intermediate.
- Categories: Chickenpox.
- Quiz: Pass the quiz to pass this course.
Please read our CPD disclaimer before enrolling.
- Understand where to seek up-to-date information on Chickenpox and vaccination including how guidance currently varies across the UK.
- Learn about the cause, characteristics and epidemiology of Chickenpox.
- Find out about the epidemiology of Chickenpox.
- Understand how to assess who is suitable for the pneumococcal vaccination.
- Understand how to address vaccine hesitancy and also learn about when it can be helpful to suggest the Chickenpox vaccination to your patients.
- Find out and become familiar with the Chickenpox vaccines available.
- Learn about how to store, prepare and administer the vaccines available.
- Describe the information you should give to patients after the vaccination.
- Pre-empt some of the questions that patients may ask.
Record your CPD
Before starting this course we recommend you reflect on what you know already. The revalidation form below is a useful tool to help you reflect on what you know before commencing the course. We will give you the chance to fill it in at the end so that you can record your learning.
Creating a record of achievement is a very important aspect of continuing professional development so we will give you a chance to complete an assessment at the end too. If you successfully complete that we will send you a record of achievement for this course.
Introduction and background
Chickenpox, also called varicella, is a common and highly infectious disease caused by the varicella-zoster virus (VZV). It is most common in children under ten years old, in whom it usually causes only mild symptoms. (1)
The chance of contracting chickenpox from household contact can be as high as 90%. Because of the high prevalence in childhood, 90% of adults raised in the UK are immune to VZ virus. Historically the incidence of chickenpox has been seasonal, with peak transmission from March to May. This seasonality has been less marked in recent years. (1)
Signs and symptoms of Chickenpox
Symptoms of chickenpox typically start with one or two days of fever and malaise. This does not always occur, particularly in young children. Fluid-filled blisters (vesicles) begin to appear on the face and head, spreading to the trunk and abdomen and finally to the limbs. (1)
The number of vesicles can range from so few as to not be noticeable, to so numerous that they combine and cover large areas of the body. After 3-4 days the blisters begin to scab over, although fresh crops of vesicles often occur. (1)
Transmission of the virus
Varicella is transmitted by direct person to person contact and by droplet spread. It can also be spread by contact with fabrics, such as clothes, bedding or towels, that have been contaminated with fluid from blisters. (1)
The incubation period before symptoms arise is between one and three weeks from the date of infection. During the first few days of symptoms, there is a high viral load in the nose and throat and in the fluid-filled vesicles before they dry up. (1)
The infectious period is from one to two days before the rash appears and until all vesicles are dry. This takes longer in people who are immunosuppressed. (1)
Following significant exposure to VZV (chickenpox or shingles), the aim of post-exposure prophylaxis is to protect individuals at high risk of severe disease and healthcare workers who may transmit to high-risk patients. (1)
Individuals should meet the following criteria: (1)
- Significant exposure to chickenpox or herpes zoster (shingles).
- A clinical condition that increases the risk of severe varicella (e.g. pregnant women, neonates and immunosuppressed patients).
- No antibodies to VZV.
Human Varicella Zoster Immuoglobulin (VZIG)
There are two licensed VZIG preparations available in the UK; distributed by Bio Products Laboratories in England and Wales and the Protein Fractionation Centre (PFC) in Scotland and Northern Ireland. (2)
VZIG is prepared from pooled plasma from non-UK donors with sufficiently high VZ antibody levels. Supply of VZIG is scarce due to the limited availability of suitable donors. Its use is therefore restricted to those at greatest risk of severe illness, or in whom the vaccines are contraindicated. (2)
VZIG is reserved for post-exposure prophylaxis of VZV in non-immune individuals at high risk of severe disease. (2)
This includes: (2)
- Pregnant women, especially up to early in the third trimester.
- Neonates whose mothers develop chickenpox within 7 days before or after delivery.
- Neonates whose mothers have no prior history of chickenpox.
- Premature infants less than 28 weeks gestation or neonates with low birth weight.
- Adults and children with no prior history of chickenpox;
- and receiving immunosuppressive therapy such as steroids, chemotherapy or radiotherapy.
- or with congenital or acquired immunodeficiency disorders.
Non-immune status will usually be confirmed by antibody testing prior to use of VZIG, to prevent wastage. (1)
National immunisation programmes
Varicella vaccination is NOT routinely recommended as part of the UK childhood immunisation programme.
- Pre-exposure vaccination: (1)
- The aim of vaccination is to protect those most at risk of serious illness from exposure.
- This is done by vaccinating healthy, non-immune close-contacts of at risk individuals (e.g. family members).
- This includes non-immune healthcare workers (who will themselves be protected from exposure in the workplace).
- Vaccination should also be offered to laboratory staff who may be exposed to VZV in the course of their work.
There are two varicella vaccines available in the UK; (1)
Both contain live attenuated virus derived from the Oka strain of varicella-zoster virus.
The vaccines are used to immunise non-immune, healthy individuals who are in regular or close contact with at-risk individuals, such as immunocompromised patients.
Specific individuals to consider include healthcare workers and family members/household contacts of immunocompromised patients.
Varivax® is licensed for vaccination against varicella in individuals from 12 months of age. Varivax® can be administered to infants from 9 months of age under special circumstances, for example in outbreak situations. (3)
Varivax® may also be administered to non-immune individuals who have been exposed to varicella (post-exposure prophylaxis). Vaccination up to 3 days post-exposure may prevent clinical infection or lessen the severity of illness. Vaccination from 3 to 5 days post-exposure may lessen the severity of illness. (3)
Varilrix® is licensed for immunisation against varicella in healthy subjects from the age of 9 months. (4)
Vaccination is recommended for non-immune, healthy, close contacts of people at risk of severe infection. The aim is to reduce the transmission of wild-type virus to high-risk patients. (4)
Close contacts include parents and siblings of high-risk patients and healthcare workers.(4)
Varivax® – dosage schedule
Individuals should receive two doses of Varivax® to ensure optimal protection against varicella. (3)
In Individuals from 9 to 12 months of age, the second dose should be given after a minimum interval of 3 months. (3)
In Individuals from 12 months to 12 years, there should be a minimum interval of one month between the first and second doses. (3)
Individuals from 13 years of age should receive two doses given 4-8 weeks apart. (3)
Varilrix® – dosage schedule
Two doses should be given to ensure optimal protection against varicella. (4)
In children from 9 to 12 months of age, the second dose should be given after a minimum interval of 3 months. (4)
In all patients, over 12 months of age, the second dose should be given after an interval of at least 6 weeks but in no circumstances less than 4 weeks. (4)
The two-dose vaccination schedule provides about 98% protection in children and about 75% protection in adolescents and adults (for the vaccine). (1)
In both age groups, those who contract varicella have fewer lesions and milder symptoms than unvaccinated individuals. (1)
For Varivax® there is data on protective efficacy for up to 9 years following vaccination. (3)
Varilrix® has demonstrated persistent efficacy up to ten years post-vaccination. (4)
The need for booster doses has not been determined yet. (3)
Pregnancy and breast-feeding
Both vaccines are contraindicated in pregnancy. (3,4)
Pregnancy should be avoided for 1 month following the second dose of the vaccine. (3,4)
It is not known if the varicella vaccine can harm the foetus, although no cases of foetal harm have been documented. (3,4)
The manufacturers of both vaccines do not recommend their use in breastfeeding mothers due to a theoretical risk of transmission to the infant. (3,4)
However, studies have shown that the vaccine virus is not transmitted to the infant during breastfeeding therefore the green book states that breastfeeding mothers can be vaccinated. (1)
Both vaccines are contraindicated in: (3,4)
- Hypersensitivity to a previous dose of any varicella vaccine.
- Hypersensitivity to any vaccine excipient, especially neomycin and gelatin.
- Pregnancy (avoid for 1-month post-vaccination).
- Blood dyscrasias, leukaemia or lymphoma.
- People receiving immunosuppressive therapy (including high-dose steroids).
- Congenital or acquired immunodeficiency.
- Active untreated tuberculosis.
- Any illness with fever >38.5°C (low-grade fever itself is not a contraindication).
Excipients listed below: (3)
- This vaccine may contain a trace amount of neomycin.
- Hydrolysed gelatin.
- Sodium chloride.
- Monosodium L-glutamate.
- Anhydrous disodium phosphate.
- Potassium dihydrogen phosphate.
- Potassium chloride.
Varilrix® excipients are listed below: (4)
- Amino acids.
- Varilrix® is contra-indicated in people with a history of hypersensitivity to neomycin.
Vaccine side effects
As with all vaccines, the rare risk of anaphylaxis should be considered and the necessary emergency treatment made available. (3,4)
Up to 10% of adults and 5% of children develop a vaccine-associated rash within one month of immunisation. (1)
Transmission of the vaccine virus to close contacts has occurred very rarely. (1)
Very rare cases of herpes zoster (shingles) have occurred. (3,4)
Below are some of the common or very common adverse effects of the vaccine. Please consult the summary of product characteristics for a comprehensive list of known adverse effects.
Very common side-effects (affecting more than 1 in 10 people) include the following: (3,4)
- Injection site pain, redness and swelling.
Common side-effects (affecting fewer than 1 in 10 people) include the following: (3,4)
- Varicella-like rash at the injection site.
- Generalised varicella-like rash.
- Upper respiratory infections (children only).
Any discomfort can be managed with paracetamol.
Salicylates (including aspirin) should be avoided for 6 weeks following vaccination due to an association with Reye’s syndrome. (3,4)
Reporting side effects
If a patient tells you about any side effects please remember to submit a report via the Yellow Card Scheme. You can report a side effect here or search for MHRA Yellow Card in the Google Play or Apple App Store.
Vaccine virus transmission
Transmission of vaccine virus from people who have been vaccinated to non-immune close contacts has been documented, but the risk is very low. (1)
All documented cases of vaccine transmission have included the presence of a post-vaccination rash. (1)
If the vaccinee develops a post-vaccination rash within four to six weeks of either dose they should avoid close contact with at-risk individuals until the rash has completely cleared. (4)
In the absence of a post-vaccination rash the risk of transmission is extremely small. (4)
The vaccine virus strain can also cause latent infection in the vaccinee and reactivate later to cause herpes zoster (shingles). The risk with the vaccine strain is substantially lower than with wild-type varicella. (1)
Co-administration with other vaccines
Varicella can be given at the same time as other live vaccines, for example, MMR.
The vaccines should be given at different sites, preferably in different limbs.
If live vaccines cannot be given simultaneously then a minimum interval of 4 weeks should be left.
Co-administration of live vaccines
After a live vaccine is given, the vaccine virus will begin to replicate and elicit an immune response. Natural interferon is produced in response to the live vaccine. (1)
If a second live vaccine is given during this time the interferon may prevent replication of the second vaccine virus. (1)
The MMR vaccine has been shown to attenuate the response to the varicella vaccine. It is therefore recommended to leave an interval of at least four weeks between live vaccines. (1)
However, if live vaccines are given simultaneously each vaccine virus will begin to replicate at the same time. Production of interferon will not affect the immune response. Live vaccines should either be given simultaneously or after an interval of four weeks. (1)
Varivax® should be administered intramuscularly (IM). It can be given subcutaneously (SC) in patients with bleeding disorders. (3)
Varilrix® should only be administered subcutaneously (SC). (4)
In all cases, the anterolateral aspect of the thigh should be used in young children and the deltoid area in older children and adults. (3,4)
We have highlighted here some of the aspects you may wish to consider around reconstitution and visual inspection of the vaccines.
Both vaccines are presented as lyophilised preparations for reconstitution with a supplied diluent. (1,3,4)
Varivax® is an off-white powder which on reconstitution produces a clear, colourless to pale yellow liquid. (3)
Varilrix® is a cream/yellow/pink-coloured pellet which on reconstitution may vary from a peach-coloured to a pink solution due to minor variations in pH. (4)
Reconstitute the vaccines using the diluent and instructions provided by the manufacturer. Gently agitate the vials until fully dissolved. (3,4)
Both reconstituted products should be checked for foreign or particulate matter and for the correct physical appearance. (3,4)
Avoid contact with alcohol or disinfectants as they may inactivate live vaccines. (3,4)
There are a number of important factors to consider when storing these vaccines. You may wish to consider the following: (1,3,4)
- All vaccines are sensitive to heat or cold to some extent.
- The unreconstituted vaccine and diluent should be stored in the original packaging at +2⁰C to +8⁰C.
- The vaccines should be used immediately after reconstitution to avoid any loss of potency.
- Reconstituted Varivax® should be discarded after 30 minutes if not used.
- Reconstituted Varilrix® vaccine can be stored at +2⁰C to +8⁰C for a maximum of one hour prior to use.
Frequently asked questions
In this section, we have called on the experience of other pharmacists running successful Chickenpox vaccination services. People accessing your service will have many questions so it is vital that you can answer, know where to access the information and also when to escalate concerns.
What should I do if I feel ill or have side effects after my vaccination?
Side effects are usually mild and can be managed with rest, plenty of water to drink and a simple analgesic such as paracetamol. You should not take aspirin for at least six weeks after your vaccination.
Could the vaccine virus be transmitted from me to my family members?
There have been very rare cases of transmission of the vaccine virus strain. These are only known to have occurred when a chickenpox-type rash has developed within 6 weeks of vaccination. If this happens you should avoid close contact with vulnerable people until the rash has completely cleared.
Can the vaccine cause shingles?
The vaccine virus strain can lie dormant in your body, just like the real infection, and reactivate later to cause shingles. This has only been documented rarely and the risk of it happening with the vaccine is much lower than with the real chickenpox infection.
Will the vaccine stop me from getting chickenpox?
No vaccine is 100% effective and some people who are vaccinated against varicella may still catch chickenpox. However varicella vaccines have been shown to be over 90% effective for up to ten years.
Can the vaccine cause chickenpox infection?
Varicella vaccines are live attenuated vaccines. This means they contain a live virus that has been weakened. The virus replicates in your body and you develop antibodies to it. Some of the side-effects of the vaccine are similar to chickenpox infection, including a rash in some cases. Symptoms are usually much milder than the disease itself.
Can anyone have the vaccine?
The vaccines are only recommended for healthy people in order to protect close contacts who are at high risk of severe disease. If you are pregnant or have a weakened immune system you may be offered varicella zoster immunoglobulin instead of a vaccine.
Final course assessment
Record your CPD
Congratulations on completing this course. Here is another chance to reflect on and record your learning. We would love to know if your knowledge has improved as a result of completing this course. We also welcome your feedback.
- Public Health England (PHE); Varicella: the green book, chapter 34; Published 20 March 2013, Last updated 26 June 2019.
- Summary of medicinal Product Characteristics (SmPC), Human Varicella-Zoster Immunoglobulin 100 IU/ml solution for injection; Bio Products Laboratory Limited, Updated 28-Mar-2019.
- Summary of medicinal Product Characteristics (SmPC), Varivax® powder and solvent for suspension for injection in a pre-filled syringe; Merck Sharp & Dohme (UK) Limited, Updated 11-Feb-2021.
- Summary of medicinal Product Characteristics (SmPC), Varilrix® 10 3.3 PFU/0.5ml powder and solvent for solution for injection; GlaxoSmithKline UK, Updated 20-Feb-2020.