• Fever - can precede the rash by 1-2 days and usually subsides by day 3 of the rash
• Rash - generally starts centrally (head and trunk) as red macules and progresses through the papular and vesicular stage before crusting. New lesions tend to appear over the first 5 days. Lesions at different stages are typically seen. They are intensely itchy and may affect any area of the body, including the pharynx and tonsils.   

In most cases diagnosis is based on clinical symptoms, and no further investigations are required. In cases of doubt send a skin swab of a wet skin lesion to virology for PCR.

In immunocompetent children over 28 days old who are otherwise healthy, anti-viral treatment is not normally required.³

For children are at risk of moderate disease (see below), consider oral Aciclovir:

These include children:

• Over 13 years of age if presenting within the first 24 hours and unvaccinated
• With concurrent severe skin disease e.g. eczema
• With pulmonary disease e.g. Cystic Fibrosis, chronic lung disease, asthma requiring inhaled steroids, interstitial lung disease.
• Taking aspirin
• Currently receiving short-course or intermittent oral corticosteroids e.g. 1-2mg/kg prednisolone for viral induced wheeze or exacerbation of asthma

Oral aciclovir can also be considered in neonates 7-28 days old who are well with limited skin lesions, particularly where there is no history of perinatal maternal varicella. The risk of severe disease in infants of this age is subject to debate, as they are usually relatively protected by maternal antibody. Oral aciclovir may be considered to reduce the duration of viral shedding, particularly in infants whose mothers have no history of chickenpox ⁴.  If presenting to ED or CDU, please discuss this with the paediatric medical registrar or ED/medical consultant prior to discharge. 

Prescribe the dose as per BNF-c ⁵

It is important to advise families on ensuring good fluid intake whilst taking aciclovir. Families should be safety-netted to return if children become more unwell or if new lesions are appearing after day 5 of illness.

In the following patients, IV aciclovir should be commenced:

Dose as per BNF-c  or for neonates please use the West of Scotland Neonatal drug monographs (Perinatal Network)

• Babies <7 days old: 7 days of treatment.
• In neonates 7-28 days old, IV aciclovir should be commenced if the infant is unwell, or if there is any doubt that the lesions could be due to HSV rather than VZV. Switch to oral aciclovir in these infants can be considered if clinical improvement, after discussion with the ID team.
• Immunocompromised Children: 7 days of treatment or until no new lesions for 48 hours (the higher BNF “immunocompromised” dose should be used). For examples of children with immune compromise, see Box 2 in Section 9. If in doubt, discuss with child’s clinical team.
• Children developing new crops of lesions for more than 5 days: Treat until 48 hours after the appearance of the last lesions, with the higher BNF “immunocompromised” dose.
• Children admitted with either virally-mediated complications, or serious bacterial complications with continuing new lesions – see Section 7 for further detail.
• Consider IV aciclovir for severe varicella in children not previously known to be immunodeficient, as this can be an indicator infection for severe immune compromise.

Aciclovir is renally excreted and has been shown to cause renal impairment, particularly in dehydrated patients. Adequate hydration should be maintained and there should be a low threshold for considering IV fluids, particularly in children on other nephrotoxic drugs. An accurate fluid balance should be recorded.  Renal profile (with creatinine) should be monitored every 2-3 days, or daily in patients with underlying renal dysfunction.  For further information and dosing in renal impairment, refer to the SmPC, sections 4.2 and 4.8. 

Symptomatic treatment for all Children:

• Paracetamol for fever
• Topical calamine can be used but there is no evidence of effect and it can dry the skin and increase itching
• Antihistamines (e.g cetirizine) can be used for itch
• Parents should be advised to keep children’s nails short, cover affected skin with loose light clothing and encourage oral fluids

NSAIDS (e.g Ibuprofen, diclofenac) are contra-indicated.

Secondary bacterial Infection

This is the most common complication

There needs to be a high index of suspicion for secondary bacterial infection if there is persisting fever beyond day 3 or recurring fever. In all children, fully expose and look for evidence of skin infection.

Children are at risk of invasive Group A Streptococcal infection and Staphylococcus aureus infection which can present as sepsis, cellulitis, pneumonia, septic arthritis, and osteomyelitis.

Cellulitis/Infected skin lesions – Treat with flucloxacillin. Low threshold for admission and IV antibiotic treatment. Consider adding clindamycin. 

Refer to the GGC guideline for Empirical antibiotic therapy in children 

NOTE: For the systemically unwell child with varicella and signs of secondary bacterial infection the antibiotic treatment regimes should all include high dose clindamycin –dose as per BNF-c

Clindamycin has high oral bio-availability and should be given orally unless there are concerns about absorption.

Necrotising Fasciitis

This is a rare complication of varicella. Consider in a child with fever, tachycardia, swelling or severe pain over an area of skin (can be present without fever). Crepitus may be present. Urgent surgical review is required, and antibiotics should be discussed with the microbiology or infectious diseases teams.

Toxic Shock Syndrome (TSS)

TSS can be associated with varicella. It is characterised by fever, hypotension, rash, multi-organ involvement and desquamation. Treatment involves fluid resuscitation and IV antibiotics – high-dose cefotaxime and clindamycin – dose as per BNF-c . PICU review should be requested. IV immunoglobulin can be considered after discussion with the infectious diseases consultant on call.  This is a blue/group 4 indication under the national demand programme.  An IVIG request form should be completed and sent to the pharmacy team.  Out of hours stocks can be obtained from the EDC (ground floor, QEUH) or PICU and the request form completed and submitted the following working day.

Varicella Pneumonia

This is more common in adolescents and adults
Patients present 1-6 days after the onset of the rash with cough, dyspnoea, fever and hypoxia with fine crackles over the lung fields.  Haemoptysis can be present. CXR shows diffuse bilateral nodular infiltrates.

Varicella pneumonia is treated with IV aciclovir - dose as per BNF-c but be aware that secondary bacterial pneumonia (especially Group A Streptococcus) is more common in children.  Concomitant antibiotics may be required.

Varicella Encephalitis

This can present with headache, vomiting, fever, confusion or seizures around 2-6 days after the onset of the rash. The need for imaging should be discussed with on call general paediatric consultant. CSF shows a pleocytosis with lymphocyte predominance

Treat with high dose IV aciclovir - CNS dose as per BNF-c and cover with cefotaxime CNS dose as per BNF-c pending CSF culture and PCR results.

Cerebellar Ataxia

This is the most common neurological complication. Patients can present at around 1 week with a developing broad-based gait. Other symptoms can include irritability, vomiting, tremor, headache, slurred speech, hypotonia and nystagmus. Children usually have a complete recovery in 2-4 weeks.

Antiviral treatments are not normally used because the disease is usually self-limiting, resolving in 1-3 weeks, and the primary pathogenic process is thought to be immune-mediated demyelination, rather than viral cytopathology.⁸

Some cases of varicella cerebellar ataxia can include cerebellitis. A rare complication can be acute hydrocephalus secondary to 4^th ventricle obstruction. Clinical assessment should look for signs of raised intracranial pressure. All cases should be discussed with the neurology team. Children presenting overnight should be admitted under the general paediatric team and discussed with the neurology team in the morning, unless there are concerns regarding raised intracranial pressure in which case urgent out of hours CT scan should be arranged.

Continuing Crops of Lesions Developing For Greater Than 5 Days.

Severe varicella is associated with prolonged viral replication. It is often associated with fever or other organ involvement. It can be a sign of immune compromise.

All children who are unwell with continuing new lesions after day 5 should be admitted for IV aciclovir -Immunocompromised dose as per BNF-c even if no previous evidence of immune compromise.

Please discuss these patients with the infectious diseases and immunology team.

Involvement of the eye

Where lesions develop that affect an eye an ophthalmology consult should be sought.

Hepatitis

Mild subclinical hepatitis is common. Liver enzymes are increased but recover without treatment. Rarely, mainly in immunocompromised patients, a symptomatic hepatitis can occur and is associated with a coagulopathy. No dose adjustment of aciclovir is necessary.

Haemorrhagic lesions/Petechiae

Haemorrhagic varicella is more likely to occur in immunocompromised children.

Thrombocytopenia can occur, but is generally asymptomatic and recovers without treatment.

In cases of petechiae, check FBC, coagulation and LFTS.

In cases of haemorrhagic varicella commence IV aciclovir- Immunocompromised dose as per BNF-c.

Where there are bacterial complications; if there is evidence of ongoing viral replication (e.g. new lesions) add in IV aciclovir, as per section 4.

Advise parents to bring their children back to hospital if they develop the following complications: 

• unusual redness, swelling or pain over an area of the rash
• refusal to drink fluids and reduced urine output/dry nappies
• high fever that persists for more than 3 days after the rash or the fever was gone and then has come back
• Change in the child’s behaviour
• Severe headache or difficulty walking
• Blisters are observed in the child’s eyes
• The child has difficulty breathing

For additional information, refer to the Healthier Together Patient Information Leaflet on Chickenpox.

The aim of post exposure prophylaxis is to protect individuals who are at high risk of severe chickenpox. Give prophylaxis to any child who is immunocompromised with a low antibody titre to Varicella Zoster Virus, after a significant exposure.² Follow the flowchart below.

Notes:

1. Some children not eligible for prophylaxis will be eligible for treatment if chickenpox develops and should therefore be advised to present if they become symptomatic – see Section 4. For other children, safety-net to present if they develop chickenpox with red flag features, as per Section 8
2. If a patient presents after day 7 of exposure, a 7 day course of antivirals can be started any time up to day 14 post exposure. The day of exposure is defined as the date of onset of the rash if the index case is a household contact OR the date of first contact.
3. Patients receiving regular intravenous or subcutaneous immunoglobulin do not require further prophylaxis, but may be offered treatment if they develop signs of infection.
4. If in doubt as to whether a child should receive post-exposure prophylaxis, contact their clinical team.

For further information, access UKHSA guidance.

Patients may still get chickenpox following prophylactic treatment and families should be advised on the symptoms and signs of infection and to present immediately should they develop.

Prophylaxis is recommended in certain groups of neonates in case of significant exposure – see Table 1 below for these scenarios.² Most at risk are neonates whose mother develops chickenpox in the week before or after delivery.

To determine if an exposure is significant, use the criteria in Box 2 in Section 9.

Table 1: adapted from: https://www.gov.uk/government/publications/post-exposure-prophylaxis-for-chickenpox-and-shingles/guidelines-on-post-exposure-prophylaxis-pep-for-varicella-or-shingles-january-2023#ref

Notes:

1. Sourcing intravenous prophylaxis
   The Varicella Zoster Immunoglobulin product available is VaritectCP. Stocks are held at the Queen Elizabeth Hospital in Glasgow. For supply, please contact your ward pharmacist in-hours, or the RHC pharmacist on-call out of hours. A drug monograph is available on the Perinatal Network website:
   https://perinatalnetwork.scot/guidance/neonatal-guidance/local-regional-drug-monographs/
   
   Where VaritectCP cannot be obtained within 96 hours of the exposure then offer IVIG immediately, rather than waiting to offer specific immunoglobulin. For dosing, see the monograph "Intravenous Immunoglobulin (IVIG) for Post Exposure Prophylaxis of Varicella" on the Perinatal Network website (link above).
   
   
2. Efficacy of VZIG and treatment of neonates who develop clinical illness
   Around 50% of infants given VZIG will still develop chickenpox but the course is likely to be milder. Families should be advised to bring the infant to hospital for assessment if symptoms or signs of chickenpox develop. Management of these infants should be discussed with the ID consultant on call following initial assessment. The incubation period of chickenpox in infants who have received VZIG can be up to 28 days.