Basis for recommendation

Admission to hospital if serious complications are suspected

• This recommendation is pragmatic, based on what CKS considers to be good clinical practice.

Prescribing aciclovir

• The recommendation on the groups for whom aciclovir should be considered is based on guidance from Public Health England (PHE) Summary of antimicrobial prescribing guidance: managing common infection [PHE, 2021a] and is supported by expert opinion in the British National Formulary (BNF) [BNF, 2021]. Adults are more likely to develop complications of chickenpox than children. People who smoke, have severe lung or cardiovascular disease, or have a chronic skin disorder, are particularly at risk from complicated chickenpox [PHE, 2015; Kimberlin, 2018].
• A review by BMJ Clinical Evidence (search date January 2014) [Cohen, 2015a] found a systematic review of three randomized controlled trials, of which two studies compared the use of aciclovir with placebo in otherwise healthy adults with chickenpox (n = 148). The findings were that:
  • Aciclovir given within 24 hours of rash onset reduced the time to full crusting of lesions and reduced the number of lesions.
  • Aciclovir given more than 24 hours after rash onset showed no significant difference in time to full crusting of lesions or time to no new lesions.
• The recommended dose, duration, and window period for treatment with aciclovir, if indicated, is based on guidance from PHE [PHE, 2021a], the BNF [BNF, 2021], and the BNF for Children [BNF for Children, 2021].
• A Cochrane systematic review on aciclovir for treating varicella in otherwise healthy children and adolescents [Klassen, 2005] did not find sufficient evidence to support the use of aciclovir in young, immunocompetent children with self-limiting, uncomplicated chickenpox.
  • From the three studies identified, aciclovir was associated with a reduction in the maximum number of lesions and the number of days with fever, but there were no differences in the occurrence of complications of chickenpox in people taking aciclovir compared with placebo. A further literature search for this Cochrane systematic review in September 2008 did not find any new evidence requiring a change to the conclusions.
  • Findings are in agreement with expert opinion in American Academy of Pediatrics The Red Book [Kimberlin, 2018].
• CKS found no recent trials looking specifically at the effect of aciclovir on preventing complications of chickenpox in an adult population.

Giving advice

• This recommendation is pragmatic and is based on what CKS considers to be good clinical practice.

Bacterial superinfection

• The recommendation to consider the possibility of bacterial superinfection is based on a case review [Sturgeon et al, 2015] and one UK study (n = 613) that found that 32% of children and 17% of adults admitted to hospital with chickenpox had secondary bacterial skin infection [Bovill, 1998].

Basis for recommendation

Self-care measures

• The recommendations on self-care measures for symptomatic relief are based on review articles on the management of chickenpox and shingles infection [Allen, 2006; Kimberlin, 2018; BMJ Best Practice, 2020].

Advice on contacts

• This recommendation is based on information on the infectious period of chickenpox and groups at increased risk of complications of chickenpox in Immunisation against infectious disease: the 'Green book', published by Public Health England (PHE) [PHE, 2015] and a guideline from the Royal College of Obstetricians and Gynaecologists on Chickenpox in pregnancy [RCOG, 2015].
• The recommendation on advice on exclusion from school and nursery is based on the PHE document Health protection in schools and other childcare facilities [PHE, 2019b].

Seeking medical advice

• This recommendation is pragmatic and is based on what CKS considers to be good clinical practice.
• The advice to consider bacterial superinfection and dehydration as potential complications is extrapolated from the National Institute for Health and Care Excellence (NICE) guideline Fever in under 5's: assessment and initial management [NICE, 2013], expert opinion in review articles [Kimberlin, 2018; BMJ Best Practice, 2020], and a case review [Sturgeon et al, 2015].

Basis for recommendation

This recommendation is based on guidance from Public Health England (PHE) [PHE, 2021a] and expert opinion in review articles [Gould, 2014; BMJ Best Practice, 2020], and is pragmatic based on what CKS considers to be good clinical practice.

Paracetamol

• The recommendation to use paracetamol to relieve pain or fever is based on a guideline from the National Institute for Health and Care Excellence (NICE) Fever in under 5's: assessment and initial management [NICE, 2019], expert opinion in American Academy of Pediatrics The Red Book [Kimberlin, 2018], review articles [Gould, 2014; BMJ Best Practice, 2020], and the UK Medicines Information service (UKMi) [UKMi, 2019]. The information on licensing for children less than 2 months of age is based on the BNF for Children [BNF for Children, 2021].

Avoidance of NSAIDs

• The recommendation on avoidance of nonsteroidal anti-inflammatory drugs (NSAIDs) is based on concerns that use of NSAIDs in varicella may be associated with an increased risk of severe skin and soft tissue infections [Gould, 2014; de Martino, 2017; Kimberlin, 2018; Stone, 2018; UKMi, 2019; BMJ Best Practice, 2020].

Calamine lotion

• Calamine lotion is thought to relieve itch by evaporating from the skin to induce a cooling effect [Allen, 2006]. CKS found no evidence on the use of calamine lotion to treat itch in chickenpox, however it is considered to be an option as it is recommended by the authors of some review articles and there is anecdotal evidence to support its use [Allen, 2006; Tebruegge et al, 2006; Gould, 2014].

Antihistamines

• There is very limited evidence to support the use of topical or systemic antihistamines in relieving pruritus in those with chickenpox. CKS has based this recommendation on expert opinion in a review article [Gould, 2014] and the fact that Piriton® (but not generic chlorphenamine), is licensed for the symptomatic relief of itching due to chickenpox [ABPI, 2021a; ABPI, 2021b]. Chlorphenamine should not be given to those less than 1 year of age as it is not licensed for use in this age group [ABPI, 2021b]. In a literature review, only one poor-quality randomized trial was found that investigated the effect of antihistamines in chickenpox [Tebruegge et al, 2006]. CKS found no other randomized trials on the effect of antihistamines (including chlorphenamine) in people with chickenpox.

Topical crotamiton and colloidal oatmeal bath additives

• CKS found no evidence to justify the recommendation of topical crotamiton and colloidal oatmeal bath additives in chickenpox.

Basis for recommendation

Admission to hospital if severe symptoms

• This recommendation is based on expert opinion in guidance from the Royal College of Obstetricians and Gynaecologists (RCOG) Chickenpox in pregnancy that lists features of potentially life-threatening chickenpox which are indications for hospital admission [RCOG, 2015] and Public Health England (PHE) Guidance on the investigation, diagnosis and management of viral illness, or exposure to viral rash illness, in pregnancy [PHE, 2019a] that lists absolute indicators and contributory factors for hospital admission.

Seeking immediate specialist advice regarding further management

• CKS recommends seeking immediate specialist advice regarding the management of a pregnant woman with chickenpox because a pregnant woman is at increased risk of developing serious complications, is more likely to require hospitalization, and needs to be assessed and counselled regarding the risk of fetal varicella syndrome. In addition, antiviral treatment may be indicated and outpatient follow up for the fetus should be arranged [PHE, 2019a].
• Pregnant women are more at risk of serious complications of varicella (for example fulminating varicella pneumonia). This risk is greatest in the second, and early in the third, trimester [PHE, 2015].
• Guidelines from PHE [PHE, 2019a] and RCOG  [RCOG, 2015] list other features that may contribute to the need for hospitalization, including difficulty monitoring the woman; gestation in the latter half of pregnancy; complicated obstetric history; history of smoking or chronic lung disease; poor social circumstances; and the use of systemic corticosteroids in the last 3 months.
• The RCOG guideline on chickenpox in pregnancy [RCOG, 2015] advises that a pregnant woman needs to be informed of the small risk of fetal varicella syndrome and its implications if she develops varicella or shows serological conversion in the first 28 weeks of pregnancy. Women who develop chickenpox in pregnancy should be referred to a fetal medicine specialist, at 16–20 weeks or 5 weeks after infection, for discussion and detailed ultrasound examination. A neonatologist should be informed of the birth of all babies born to women who have had chickenpox at any gestation during pregnancy [RCOG, 2015].

Primary care management

• CKS recommends that oral antiviral treatment should only be prescribed in primary care on the advice of a specialist as there are limited data on the treatment of chickenpox in pregnancy. The UK Teratology Information Service (UKTIS) found that data on pregnancy/infant outcomes other than congenital malformation in pregnant women with exposure to aciclovir have not been adequately studied to allow evidence-based assessment of risk — UKTIS advise that this along with known risks posed by varicella infection in pregnancy should be considered when discussing treatment options [UKTIS, 2020].
• Guidance from the UK Health Security Agency (UKHSA) advises that all women exposed to chicken pox from 20 weeks gestation should be offered anti-viral post-exposure prophylaxis [UKHSA, 2023].
• Guidance from PHE and RCOG on chickenpox in pregnancy [RCOG, 2015; PHE, 2019a] recommends offering a 7-day course of oral aciclovir (with informed consent following a discussion with an obstetrician) if the woman presents within 24 hours of the onset of the chickenpox rash and is 20 weeks pregnant or more. The RCOG guideline also states that the use of aciclovir in pregnancy is off-label, therefore a discussion with the woman should include the risks and potential benefits [RCOG, 2015].
• If the woman is less than 20 weeks pregnant PHE and RCOG state that aciclovir should be considered with caution [RCOG, 2015; PHE, 2019a].
• Intravenous aciclovir is indicated if chickenpox is severe or there are any complications [PHE, 2019a].
• The recommendation to offer symptomatic treatment and give advice is based on expert opinion in review articles [Gould, 2014; BMJ Best Practice, 2020], and is pragmatic, based on what CKS considers to be good clinical practice.
• CKS recommends close monitoring of the woman and referral for urgent hospital assessment if fever persists or cropping of the rash continues after 6 days based on the PHE guideline Guidance on the investigation, diagnosis and management of viral illness, or exposure to viral rash illness, in pregnancy [PHE, 2019a].
• The recommendation to consider the possibility of bacterial superinfection is based on a case review [Sturgeon et al, 2015] and one UK study (n = 613) that found that 32% of children and 17% of adults admitted to hospital with chickenpox had secondary bacterial skin infection [Bovill, 1998].

Basis for recommendation

Self-care measures

• The recommendations on self-care measures for symptomatic relief are based on review articles covering the management of chickenpox infection [Allen, 2006; BMJ Best Practice, 2020].

Advice on contacts

• This recommendation is based on information on the infectious period of chickenpox and groups at increased risk of complications of chickenpox in Immunisation against infectious disease: the 'Green book', published by Public Health England (PHE) [PHE, 2015].

Seeking medical advice

• This recommendation is pragmatic and is based on what CKS considers to be good clinical practice and expert opinion in Immunisation against infectious disease: the 'Green book', published by PHE, which states that pregnant woman are at increased risk of severe disease and fulminating varicella pneumonia [PHE, 2015].

Basis for recommendation

Paracetamol and NSAIDs

• The recommendation to use paracetamol for pain and fever is based on expert opinion in review articles [Gould, 2014; BMJ Best Practice, 2020]. Paracetamol is not known to be harmful in pregnancy [BNF, 2021].
• Ibuprofen should be avoided because of concerns that use of nonsteroidal anti-inflammatory drugs (NSAIDs) in varicella may be associated with an increased risk of severe skin and soft tissue infections [Gould, 2014; de Martino, 2017; Kimberlin, 2018; Stone, 2018; UKMi, 2019; BMJ Best Practice, 2020]. In addition, UK Teratology Information Service recommends that use of ibuprofen is not advised in pregnancy, especially after 30 weeks of gestation when is associated with an increased risk of premature closure of the ductus arteriosus and oligohydramnios [UKTIS, 2019a].

Calamine lotion

• Calamine lotion is thought to relieve itch by evaporating from the skin to induce a cooling effect [Allen, 2006]. 
• CKS found no evidence on the use of calamine lotion to treat itch in chickenpox, however it is considered to be an option as it is recommended by the authors of some review articles and there is anecdotal evidence to support its use [Allen, 2006; Tebruegge et al, 2006; Gould, 2014].
• There is no available evidence on the safety of calamine lotion during pregnancy and lactation, however it has been used for many years with no reports of adverse effects [ABPI, 2016].

Chlorphenamine

• CKS found no evidence to support the use of chlorphenamine in pregnant women with chickenpox.
• Limited available data do not suggest an increase in the overall risk of congenital malformations if chlorphenamine is used in pregnancy [UKTIS, 2019b]. However, the manufacturer of chlorphenamine advises not using the drug during pregnancy unless considered by a physician to be essential [ABPI, 2021a]. Taking into account the lack of evidence that chlorphenamine offers symptomatic benefit in people with chickenpox, CKS does not recommend its use in pregnant women.

Topical crotamiton and colloidal oatmeal bath additives

• CKS found no evidence to justify the recommendation of topical crotamiton and colloidal oatmeal bath additives in chickenpox.

Basis for recommendation

Admission to hospital

• This recommendation is pragmatic, based on what CKS considers to be good clinical practice and the fact that chickenpox can be more severe in adults compared with children [PHE, 2015].

Antiviral treatment

• The recommendation on the groups for whom aciclovir should be considered is based on guidance from Public Health England (PHE) Summary of antimicrobial prescribing guidance: managing common infections [PHE, 2021a] and is supported by expert opinion in the British National Formulary [BNF, 2021]. Adults are more likely to develop complications of chickenpox than children. People who smoke, have severe lung or cardiovascular disease, or have a chronic skin disorder, are particularly at risk from complicated chickenpox [PHE, 2015; Kimberlin, 2018].
• A review by BMJ Clinical Evidence (search date January 2014) [Cohen, 2015a] found a systematic review of three randomized controlled trials, of which two studies compared the use of aciclovir with placebo in otherwise healthy adults with chickenpox (n = 148). The findings were that:
  • Aciclovir given within 24 hours of rash onset reduced the time to full crusting of lesions and reduced the number of lesions.
  • Aciclovir given more than 24 hours after rash onset showed no significant difference in time to full crusting of lesions or time to no new lesions.
• The recommended dose, duration, and window period for treatment with aciclovir, if indicated, is based on guidance from PHE [PHE, 2021a]; oral aciclovir 800 mg 5 times a day for 7 days for an immunocompetent, non-pregnant adult or adolescent (aged 14 years or older) with chickenpox who presents within 24 hours of rash onset, particularly for people with severe chickenpox or those at increased risk of complications, such as smokers.
• CKS found no recent trials looking specifically at the effect of aciclovir on preventing complications of chickenpox in an adult population.

Seeking urgent specialist advice about whether a mother should continue to breastfeed

• CKS advises seeking specialist advice regarding whether a mother with chickenpox should breastfeed in view of the risk of the infant developing chickenpox, and advice from the British National Formulary [BNF, 2021] and the manufacturer's Summary of Product Characteristics [ABPI, 2020] to use aciclovir when breastfeeding 'with caution'.
• Aciclovir is present at low concentrations in breastmilk and is not expected to adversely affect the infant; although data is limited it is considered to be the antiviral of choice where indicated for breastfeeding women [LactMed, 2018; SPS, 2020].
• Guidance from the Royal College of Obstetricians and Gynaecologists (RCOG) and PHE state that women with chickenpox should breastfeed if they wish to and are well enough to do so. If there are active chickenpox lesions close to the nipple, they should express breast milk from the affected breast until the lesions have crusted over. The expressed breast milk may be fed to the baby who is receiving treatment with varicella-zoster immunoglobulin and/or aciclovir [RCOG, 2015; PHE, 2019a]. These treatments should be initiated by a specialist.

Giving advice

• This recommendation is pragmatic, and is based on what CKS considers to be good clinical practice.

Bacterial superinfection

• The recommendation to consider the possibility of bacterial superinfection is based on a case review [Sturgeon et al, 2015] and one UK study (n = 613) that found that 32% of children and 17% of adults admitted to hospital with chickenpox had secondary bacterial skin infection [Bovill, 1998]. 

Basis for recommendation

Self-care measures

• The recommendations on self-care measures for symptomatic relief are based on review articles on the management of chickenpox [Allen, 2006; BMJ Best Practice, 2020].

Advice on contacts

• This recommendation is based on information on the infectious period of chickenpox and groups at increased risk of complications of chickenpox in Immunisation against infectious disease: the 'Green book', published by Public Health England [PHE, 2015] and a guideline from the Royal College of Obstetricians and Gynaecologists on Chickenpox in pregnancy [RCOG, 2015].

Seeking medical advice

• This recommendation is pragmatic and is based on what CKS considers to be good clinical practice and expert opinion in Immunisation against infectious disease: the 'Green book', published by Public Health England [PHE, 2015]. 

Basis for recommendation

This recommendation is based on guidance from Public Health England [PHE, 2021a] and expert opinion in review articles [Gould, 2014; BMJ Best Practice, 2020], and is pragmatic based on what CKS considers to be good clinical practice.

Paracetamol

• The recommendation to use paracetamol to relieve pain or fever is based on expert opinion in review articles [Gould, 2014; BMJ Best Practice, 2020] and the UK Medicines Information service [UKMi, 2015]. Paracetamol is not considered to be harmful in breastfeeding [BNF, 2021].

Avoidance of NSAIDs

• The recommendation on avoidance of nonsteroidal anti-inflammatory drugs (NSAIDs) is based on concerns that use of NSAIDs in varicella may be associated with an increased risk of severe skin and soft tissue infections [Gould, 2014; de Martino, 2017; Stone, 2018; UKMi, 2019; BMJ Best Practice, 2020].

Calamine lotion

• Calamine lotion is thought to relieve itch by evaporating from the skin to induce a cooling effect [Allen, 2006].
• CKS found no evidence on the use of calamine lotion to treat itch in chickenpox, however it is considered to be an option as it is recommended by the authors of some review articles and there is anecdotal evidence to support its use [Allen, 2006; Tebruegge et al, 2006; Gould, 2014].

Antihistamines

• Although Piriton® (but not generic chlorphenamine) is licensed for relief of itching associated with chickenpox [ABPI, 2021a], there is very limited evidence to support the use of topical or systemic antihistamines in relieving pruritus in people with chickenpox. Given the lack of evidence of effectiveness and the manufacturer's Summary of Product Characteristics stating that chlorphenamine may inhibit lactation, may be secreted in breast milk, and should only be used for breastfeeding women if considered essential [ABPI, 2021a], CKS does not recommend its use in breastfeeding women.

Topical crotamiton and colloidal oatmeal bath additives

• CKS found no evidence to justify the recommendation of topical crotamiton and colloidal oatmeal bath additives in chickenpox.

Basis for recommendation

Seeking immediate specialist advice regarding further management

• CKS recommends seeking specialist advice on the management of neonates with chickenpox because of the increased risk of severe disease and complications in this group [PHE, 2015; RCOG, 2015; PHE, 2021a] and the potential need for specialist treatment such as intravenous aciclovir [PHE, 2019a; Holland, 2020].

Giving advice on contact with other people

• This recommendation is pragmatic and based on what CKS considers to be good clinical practice.

Basis for recommendation

Admission to hospital

• This recommendation is pragmatic and is based on what CKS considers to be good clinical practice.
• Immunocompromised people with chickenpox are at increased risk of developing complications (such as pneumonia, encephalitis, hepatitis, and disseminated intravascular coagulopathy) [CDC, 2021].

Seeking specialist advice

• CKS recommends seeking specialist advice on the management of immunocompromised people with chickenpox because of the increased risk of severe disease and complications in this group, and the need for close monitoring [PHE, 2015; CDC, 2021; PHE, 2021a].
• Chickenpox may be more difficult to diagnose in immunocompromised people as they may have an atypical rash with more lesions (which can be haemorrhagic). The duration of illness may also be increased compared with an immunocompetent person [CDC, 2021].
• Even immunocompromised people who have received varicella-zoster immunoglobulin prophylaxis may develop severe or fatal varicella. Immunocompromised people should be carefully monitored and given aciclovir at the first sign of illness [PHE, 2015].

Advice about contact and seeking medical advice

• This recommendation is pragmatic, based on what CKS considers to be good clinical practice.

Basis for recommendation

Self-care measures

• The recommendations on self-care measures for symptomatic relief are based on review articles covering the management of chickenpox infection [Allen, 2006; BMJ Best Practice, 2020].

Advice on contacts

• This recommendation is based on information on the infectious period of chickenpox and groups at increased risk of complications from chickenpox in Immunisation against infectious disease: the 'Green book', published by Public Health England [PHE, 2015], information on chickenpox from the US Centers for Disease Control and Prevention [CDC, 2021], and a guideline from the Royal College of Obstetricians and Gynaecologists Chickenpox in pregnancy [RCOG, 2015].
• The recommendation on advice on exclusion from school and nursery is based on the Public Health England document Health protection in schools and other childcare facilities [PHE, 2019b].

Seeking medical advice

• This recommendation is pragmatic and is based on what CKS considers to be good clinical practice.
• The advice to bear in mind bacterial superinfection and dehydration as potential complications is extrapolated from the National Institute for Health and Care Excellence guideline Fever in under 5's: assessment and initial management [NICE, 2019], expert opinion in a review article [BMJ Best Practice, 2020], and a case review [Sturgeon et al, 2015].

Basis for recommendation

This recommendation is based on guidance from Public Health England (PHE) [PHE, 2021a] and expert opinion in review articles [Gould, 2014; BMJ Best Practice, 2020], and is pragmatic based on what CKS considers to be good clinical practice.

Paracetamol

• The recommendation to use paracetamol to relieve pain or fever is based on a guideline from the National Institute for Health and Care Excellence (NICE) Fever in under 5's: assessment and initial management [NICE, 2019], expert opinion in American Academy of Pediatrics The Red Book [Kimberlin, 2018], review articles [Gould, 2014; BMJ Best Practice, 2020], and the UK Medicines Information service (UKMi) [UKMi, 2019]. The information on licensing for children less than 2 months of age is based on the BNF for Children [BNF for Children, 2021].

Avoidance of NSAIDs

• The recommendation on avoidance of nonsteroidal anti-inflammatory drugs (NSAIDs) is based on concerns that use of NSAIDs in varicella may be associated with an increased risk of severe skin and soft tissue infections [Gould, 2014; de Martino, 2017; Kimberlin, 2018; Stone, 2018; UKMi, 2019; BMJ Best Practice, 2020].

Calamine lotion

• Calamine lotion is thought to relieve itch by evaporating from the skin to induce a cooling effect [Allen, 2006]. CKS found no evidence on the use of calamine lotion to treat itch in chickenpox, however it is considered to be an option as it is recommended by the authors of some review articles and there is anecdotal evidence to support its use [Allen, 2006; Tebruegge et al, 2006; Gould, 2014].

Antihistamines

• There is very limited evidence to support the use of topical or systemic antihistamines in relieving pruritus in those with chickenpox. CKS has based this recommendation on expert opinion in a review article [Gould, 2014] and the fact that Piriton® (but not generic chlorphenamine) is licensed for the symptomatic relief of itching due to chickenpox [ABPI, 2021a; ABPI, 2021b]. Chlorphenamine should not be given to those less than 1 year of age as it is not licensed for use in this age group [ABPI, 2021b]. In a literature review, only one poor-quality randomized trial was found that investigated the effect of antihistamines in chickenpox [Tebruegge et al, 2006]. CKS found no other randomized trials on the effect of antihistamines (including chlorphenamine) in people with chickenpox.

Topical crotamiton and colloidal oatmeal bath additives

• CKS found no evidence to justify the recommendation of topical crotamiton and colloidal oatmeal bath additives in chickenpox.

Significant exposure

• Significant exposure takes into account:
  • The type of varicella-zoster infection in the index case. Exposure is significant if the person has had contact with:
    • Chickenpox.
    • Disseminated zoster.
    • Immunocompetent people with exposed lesions (for example ophthalmic zoster).
    • Immunocompromised people with localized zoster on any part of the body (because this group may have increased viral shedding).
  • The timing of exposure in relation to the rash onset in the index case. Exposure is significant if the person was in contact with:
    • Chickenpox — from 24 hours before onset of rash to crusting of lesions.
    • Disseminated zoster — from 48 hours before onset of rash to crusting of lesions.
    • Localized zoster — day of onset of rash until crusting of lesions.
  • Closeness and duration of contact. Exposure is significant if it is through:
    • Maternal/neonatal contact.
    • Continuous home contact.
    • Contact in the same room (for example house or classroom) for 15 minutes or more, or contact on large open wards (particularly paediatric wards).
    • Face-to-face contact (for example having a conversation).

[PHE, 2015]

Basis for recommendation

• This recommendation is extrapolated from Immunisation against infectious disease: the 'Green book' [PHE, 2015] and Chickenpox: public health management and guidance [PHE, 2014 (updated 2019)] published by Public Health England and a guideline from the Royal College of Obstetricians and Gynaecologists on Chickenpox in pregnancy [RCOG, 2015].
• Post-exposure management aims to protect people at high risk of developing varicella and people who may transmit infection to those at high risk (for example healthcare workers) [PHE, 2015; UKHSA, 2023]. 

Basis for recommendation

Assessment

• This recommendation is based on Immunisation against infectious disease: the 'Green book' published by Public Health England [PHE, 2015] and the Royal College of Obstetricians and Gynaecologists guideline Chickenpox in pregnancy [RCOG, 2015].

Establishing immunity

• These recommendations are based on guidance from Public Health England Immunisation against infectious disease: the 'Green book' [PHE, 2015] and extrapolated from Guidance on the investigation, diagnosis and management of viral illness, or exposure to viral rash illness, in pregnancy [PHE, 2019a] which states that 'If a woman has a past history of chickenpox or shingles or two doses of a varicella containing vaccine, and is not immunosuppressed, protection can be assumed and reassurance given’ [PHE, 2019a].

Healthcare workers

• Recommendations are based on Immunisation against infectious disease: the 'Green book' [PHE, 2015] which states that healthcare workers (who have patient contact) who have a definite history of chickenpox or shingles can be considered protected. Those who have a negative or uncertain history of chickenpox or herpes zoster should be serologically tested and vaccine offered to those without varicella-zoster antibody.

Basis for recommendation

Assessment

• This recommendation is based on guidance from Public Health England (PHE) Immunisation against infectious disease: the 'Green book' [PHE, 2015] and Guidance on the investigation, diagnosis and management of viral illness, or exposure to viral rash illness, in pregnancy [PHE, 2019a] and the Royal College of Obstetricians and Gynaecologists (RCOG) Chickenpox in pregnancy [RCOG, 2015].

Reassurance if definite history of chickenpox or shingles

• This recommendation is based on guidance from PHE [PHE, 2019a] which states that 'If a woman has a past history of chickenpox or shingles or two doses of a varicella containing vaccine, and is not immunosuppressed, protection can be assumed and reassurance given’, guidance from RCOG [RCOG, 2015], and expert opinion in a review article [Holland, 2020].

No history of chickenpox and a history of significant contact

• CKS recommends seeking urgent specialist advice if a woman has no history of chickenpox and has had significant contact because of the risk of more serious illness and complications in pregnant women and the potential implications for the fetus [PHE, 2015].
• The recommendation on establishing the stage of gestation is based on Immunisation against infectious disease: the 'Green Book' which states that the risks to the fetus and neonate from maternal chickenpox are dependent on when the mother was infected [PHE, 2015]. 
• Antiviral agents are recommended for all pregnant women for post-exposure prophylaxis. VZIG may be used as post-exposure prophylaxis in those women for whom oral antivirals are contraindicated [PHE, 2015; PHE, 2014 (updated 2019); UKHSA, 2023].
• The statement that testing for varicella-zoster immunoglobulin G (VZV IgG) antibodies in primary care may be appropriate if results can be available within 24–48 hours of first exposure (to allow time for referral to secondary care for antiviral treatment where necessary) is based on guidance from RCOG [RCOG, 2015] and PHE [PHE, 2019a; PHE, 2021b].
• The recommendations on results of VZV IgG testing are based on guidance from PHE UK Standards for Microbiology Investigations: investigation of exposure to vesicular and non-vesicular rash in pregnancy [PHE, 2021b] and the RCOG guideline Chickenpox in pregnancy [RCOG, 2015].

Seeking urgent advice if rash develops after contact with chickenpox

• This recommendation is based on guidance from PHE Immunisation against infectious disease: the 'Green Book' [PHE, 2015] which advises that severe chickenpox can occur in a susceptible pregnant woman, even after VZIG prophylaxis, and that aciclovir treatment is required in this situation, and the UK Standards for Microbiology Investigations: investigation of exposure to vesicular and non-vesicular rash in pregnancy [PHE, 2021b].

Basis for recommendation

Assessment

• This recommendation is based on Immunisation against infectious disease: the 'Green book', published by Public Health England (PHE) [PHE, 2015] and the Royal College of Obstetricians and Gynaecologists (RCOG) guideline Chickenpox in pregnancy [RCOG, 2015].

Determining timing of contact 

• Immunisation against infectious disease: the 'Green book' advises giving varicella-zoster immunoglobulin (VZIG) to the neonate depending on when the mother develops varicella in relation to delivery [PHE, 2015]. This should only be done in a specialist setting.

Seeking urgent specialist advice

• CKS recommends seeking urgent specialist advice on the management of a neonate who has been exposed to chickenpox or shingles because severe disease or complications can develop in this group. Depending on the time of exposure, VZIG may be required. This is only available in secondary care.
  • Guidance from PHE [PHE, 2015; PHE, 2019a] states that around half of neonates exposed to maternal varicella become infected despite VZIG prophylaxis. Up to two-thirds of these infections are mild or asymptomatic but rare fatal cases have been reported where onset of maternal chickenpox occurred in the period 4 days before to 2 days after delivery. Early treatment with intravenous aciclovir is recommended for infants in this exposure category who develop varicella despite VZIG prophylaxis.
• CKS advises seeking specialist advice regarding whether a mother with chickenpox should breastfeed in view of the risk of the infant developing chickenpox, and advice from the British National Formulary [BNF, 2021] and the manufacturer's Summary of Product Characteristics [ABPI, 2020] to use aciclovir when breastfeeding 'with caution'.
  • Guidance from RCOG and PHE state that women with chickenpox should breastfeed if they wish to and are well enough to do so. If there are active chickenpox lesions close to the nipple, they should express breast milk from the affected breast until the lesions have crusted over. The expressed breast milk may be fed to the baby who is receiving treatment with varicella-zoster immunoglobulin and/or aciclovir [RCOG, 2015; PHE, 2019a]. These treatments should be initiated by a specialist.

Basis for recommendation

Assessment

• This recommendation is based on Immunisation against infectious disease: the 'Green book' published by Public Health England [PHE, 2015] and extrapolated from the Royal College of Obstetricians and Gynaecologists guideline Chickenpox in pregnancy [RCOG, 2015].

Seeking specialist advice

• CKS recommends urgently seeking specialist advice on the management of an immunocompromised person who has been in contact with chickenpox, in view of the potential for severe disease and complications in this group [PHE, 2015; CDC, 2021].

Testing for varicella-zoster antibody

• People who have had a significant exposure to chickenpox and who are immunocompromised should be tested for varicella-zoster antibody, regardless of their history of chickenpox [PHE, 2015]. CKS recommends seeking specialist advice to determine whether it is appropriate to do this in primary care. 
  • Testing for varicella-zoster immunoglobulin G (IgG) antibodies in primary care may be appropriate. However, local arrangements may differ and testing in secondary care and/or varicella-zoster immunoglobulin prophylaxis may be needed [PHE, 2015]. This should be administered in a specialist setting.