With thanks to Dr Vicky Agunloye, paediatric registrar and new Waltham Forest mum, for kicking off her parental FAQ series with a question that many GPs ring and ask me – and I always have to look it up…

Chicken pox , Varicella-Zoster Virus (VZV), is a common infection spread by droplet inhalation of the VZV from contacts with either chicken pox or shingles.

Most children have a mild disease course; however those that are immuno-compromised are at a significant risk of severe or fatal disease and need human Varicella Zoster Immunogloblin (VZIG) as soon as possible. Some neonates (<=7 days old) come into this category.

Who needs VZIG? :

1. Infants whose mothers develop chickenpox (but not herpes zoster) in the period 7 days before to 7 days after delivery. VZIG can be given without antibody testing in these infants.
2. An infant who has had significant contact  with a case of varicella when < 7 days of age and whose contact of VZV was not the mother and mother has no positive history of VZV herself.  In these cases, the VZIG should not be given past 7 days after the initial contact.

(Confirm patient has had significant contact, Box 1 in: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/327762/Chickenpox_immunoglobulin_Oct_2008.pdf )

Who does not need VZIG?

1. Term infants > 7 days old, even if they have had significant contact
2. An infant that has not had significant contact, see above.
3. A term infant who is < 7 days old, whose mother has a positive protective history of VZV.
4. Infants who have been exposed >10 days ago.

Whose VZV anti-bodies need checking before you can decide if VZIG is needed?

1. Infants <7 days whose mothers are unsure of their VZV status (you can check mothers or infants). However do not delay more than 7 days waiting for results.

Inform mothers that up to 50% of neonates exposed to maternal VZV who get VZIG still go on to get chickenpox, most are mild cases.

If infant becomes symptomatic despite VZIG, IV acyclovir is needed.

Other useful links:

1. http://cks.nice.org.uk/chickenpox#!scenariorecommendation:9
2. Page 434-435: http://www.clinicalguidelines.scot.nhs.uk/Renal%20Unit%20Guidelines/Nephrotic%20syndrome%20Guideline/Varicella%20doc.pdf