Chicken Pox Contacts in Immunosuppressed Children on Methotrexate, Biologics or Steroids
Flowchart
Introduction, Scope & Purpose
Varicella Zoster Virus (VZV) is a common, highly infectious virus spread by droplets or direct contact that causes chicken pox (varicella) and shingles (zoster). Chicken pox occurs most commonly in the spring time, however shingles occurs with equal frequency throughout the year.

A prodrome of one to two days of fever and malaise occurs infrequently in children. The pruritic rash of chicken pox usually starts centrally on the face, scalp, trunk and abdomen and may spread to the limbs. The rash occurs in crops and typically evolves from a maculopapular rash to vesicles or pustules, which subsequently scab over during the course of several days. The rash is often accompanied by fever. The typical duration is 5-7 days. The patient can be considered noninfectious once no new lesions are appearing and all existing lesions are scabbed dry. The secondary infection rate from household contact with a case of chickenpox can be as high as 90% and secondary cases are more likely to be more severe than primary cases due to the intensity of exposure. Transmission of VZV is most likely to take place in the early stages of chickenpox and for practical purposes a patient should be considered potentially infectious 1-2 days before the rash appears.

Herpes zoster (shingles) is caused by the reactivation of the varicella virus. Vesicles appear unilaterally in within 1-3 dermatomes, representing cranial or spinal ganglia where the virus has been dormant. Transmission can occur from patients with zoster as the lesions contain VZV, however it is much less contagious than chicken pox.

Patients starting immune suppressing drugs are tested for immunity via VZV IgG (Varicella Zoster Virus Immunoglobulin G) and if negative (level <150mIU/ml), they should be vaccinated if time allows (see definition section for immune suppressed patients) at least 4 weeks prior to starting immunosuppressive agents. Varicella vaccination may occur in those on Methotrexate as long as they are not also on steroids or other immune suppressive agents. The vaccines are live attenuated vaccines, given as two doses. The second dose should be given a minimum four weeks after the first dose. A mild rash may occur several weeks after the first dose. Two doses are 98% effective at preventing severe varicella.

Immunosuppressed patients are particularly at risk of developing disseminated or haemorrhagic varicella disease and so managing contacts effectively is important. Decisions need to be made regarding withholding doses of immune suppressive medication such as methotrexate and biologics or if steroid doses should be reduced (avoid abrupt withdrawal of high dose or long term steroids due to risk of adrenal crisis, and discuss with the local secondary care team lead/tertiary rheumatology centre for advice).

If an immunosuppressed child develops what appears to be chicken pox, but there is doubt, the diagnosis may be confirmed by swabbing the skin lesions (swab must be sent in viral transport medium) and by sending the sample to virology for VZV PCR. Blood (EDTA) for VZV PCR is an alternative if no vesicular fluid can be obtained, if there is strong clinical suspicious of chicken pox in an immunosuppressed child, treatment should be started, even if the blood VZV PCR is negative. Results are likely to take 48-72 hours.

Aciclovir is now used for both prophylaxis and treatment if symptomatic (See flow chart). If the patient has renal impairment e.g. Lupus nephritis, they may need a dose reduction or consideration for VZIG (Varicella Zoster Immunoglobulin can be given IM up to 10 days post exposure; supplies of VZIG are very limited and therefore should only be used where there is no good alternative). Prophylaxis is given from day 7, but may be beneficial up to day 14 from exposure (depending on when they present to you) and given for 7 days. 

Dose is 10mg/kg orally (up to max 800mg) 4 times a day and immune suppression is continued. If they develop chickenpox despite prophylaxis for urgent review and convert to full treatment dose and withhold DMARD or biologic until all spots crusted over. May need IV Aciclovir (as per BNFc dosing) until systemically well and no new lesions for 48 hours. Treatment is usually for 7 days. 

This is for all health care professionals having contact from patients who are are immune suppressed across the network. The policy applies in all health care settings including both primary care and secondary care areas. The aim is to ensure patients receive appropriate prophylaxis or treatment for chickenpox contacts, and that there is clear guidance when to withhold doses of immune suppressing drugs.
Definitions​
Immune Suppressed Patients
Patients who receive prednisolone at a daily dose (or its equivalent) of 2mg/kg/day for at least one week, or 1mg/kg/day for one month. For adolescents, an equivalent dose should be considered in those who receive 40mg of prednisolone per day for more than one week. Those on Methotrexate or other Disease Modifying Antirheumatic drugs (for example Azathioprine, MMF, Ciclosporin, Cyclophosphamide and Baricitinib) or biologic drugs (for example Adalimumab, Etanercept, Infliximab, Tocilizumab, Anakinra, Canakinumab, Abatacept, Rituximab, Secukinumab). All patients receiving systemic high-dose steroids are immune suppressed until at least three months after treatment has stopped.

Varicella Immunity
Those with Varicella IgG >150mIU/ml, or a detected VZV IgG response if your lab does not quantify levels, on blood testing are considered to have immunity. If the test is negative this means a level of <150mIU/ml was detected and they are not immune. 

Significant Varicella Contact
Usually considered to be in the same room for more than 15 minutes.
Guideline
As per Flowchart
Communication & Training Plans
Guideline will be made available on the PIER website, dissemination and raised awareness can occur via network leads at each center. This document can also be referenced in clinic letters by local rheumatology leads when being sent to GPs to raise awareness of it. 
Process for Monitoring Compliance
The purpose of monitoring is to provide assurance that the agreed approach is being followed. This ensures that we get things right for patients, use resources well and protect our reputation. Our monitoring will therefore be proportionate, achievable and deal with specifics that can be assessed or measured.
References​
  1. The Green Book chapter 34 Varicella
  2. BNFc Varicella-Zoster Immunoglobulin
  3. BNFc Aciclovir
  4. British Society for Rheumatology Guideline: Methotrexate use in paediatric and adolescent rheumatology : Information for health professionals
  5. Wessex Paediatric Oncology Guidelines: Management of viral infections, viral prophylaxis and vaccination guidance
  6. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment _data/file/812526/PHE_PEP_VZIG_guidance_for_health_professionals.pdf
Document Version: 
1.0

Lead Authors: 
Dr Lisa Bray, Paediatric Rheumatology Consultant, St. Richard's Hospital
​Dr Chrissie Jones, Paediatric ID Consultant, UHS
Approving Network:
Wessex Paediatric Rheumatology Network

Date of Approval: 
April 2022

Review Due:
April 2025