Varicella-zoster infection (chickenpox and shingles)

Queensland Health Guidelines for Public Health Units

Revision History

• Infectious Agent
• Notification Criteria
• Notification Procedure
• Public Health Significance and Occurrence
• Clinical Features
• Reservoir
• Mode of Transmission
• Incubation Period
• Period of Communicability
• Susceptibility and Resistance
• Management
• Preventive Measures
• References

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Infectious Agent

The infectious agent is Varicella zoster virus (human herpesvirus 3).

Notification Criteria

Varicella (chickenpox)

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires either:

1. Laboratory definitive evidence AND clinical evidence
   OR
2. Clinical evidence AND epidemiological evidence.

Laboratory definitive evidence

1. Isolation of varicella-zoster virus from a skin or lesion swab. If the case received varicella vaccine between 5 and 42 days prior to the onset of rash the virus must be confirmed to be a wild-type strain
   OR
2. Detection of varicella-zoster virus from a skin or lesion swab by nucleic acid testing. If the case received varicella vaccine between 5 and 42 days prior to the onset of rash the virus must be confirmed to be a wild type strain
   OR
3. Detection of varicella-zoster virus antigen from a skin or lesion swab by direct fluorescent antibody. If the case received varicella vaccine between 5 and 42 days prior to the onset of rash the virus must be confirmed to be a wild type strain
   OR
4. IgG seroconversion or a significant increase in antibody level, such as a fourfold or greater rise in titre to varicella-zoster virus (VZV) EXCEPT if the case has received a VZV-containing vaccine 8 days to 8 weeks prior to convalescent specimen collection. (NOTE: paired sera must be tested in parallel)

Clinical evidence

Acute onset of a diffuse maculopapular rash developing into vesicles within 24 – 48 hours and forming crusts (or crusting over) within 5 days.

Epidemiological evidence

An epidemiological link is established when there is:

1. Contact between two people involving a plausible mode of transmission at a time when:
   a.  one of them is likely to be infectious
   AND
   b.  the other has illness 10 – 21 days after contact
   AND
2. At least 1 case in the chain of epidemiologically-linked cases is laboratory confirmed.

Probable case

A probable case requires clinical evidence only.

Note: Laboratory confirmation should be strongly encouraged for vaccinated cases. If positive, samples should be referred for identification as a vaccine or wild type strain.

Herpes zoster (shingles)

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory evidence AND clinical evidence.

Laboratory definitive evidence

1. Isolation of varicella-zoster virus from a skin or lesion swab
   OR
2. Detection of varicella-zoster virus from a skin or lesion swab by nucleic acid testing
   OR
3. Detection of varicella-zoster virus antigen from a skin or lesion swab by direct fluorescent antibody.

Clinical evidence

A vesicular skin rash with a dermatomal distribution that may be associated with pain in skin areas supplied by sensory nerves of the dorsal root ganglia.

Probable case

A probable case requires clinical evidence only.

Note: Laboratory confirmation should be strongly encouraged for vaccinated cases. If positive, samples should be referred for identification as a vaccine or wild type strain.

Varicella-zoster infection - (not elsewhere classified)

Only confirmed cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence, either in the absence of clinical information or where clinical evidence does not meet criteria for varicella-zoster infection (chickenpox) or varicella-zoster infection (shingles).

Laboratory definitive evidence

1. Isolation of varicella-zoster virus
   OR
2. Detection of varicella-zoster virus by nucleic acid testing
   OR
3. Detection of varicella-zoster virus antigen by direct fluorescent antibody
   OR
4. IgG seroconversion or a significant increase in antibody level, such as a fourfold or greater rise in titre to varicella-zoster virus (VZV) EXCEPT if the case has received a VZV-containing vaccine 8 days to 8 weeks prior to convalescent specimen collection. (NOTE: paired sera must be tested in parallel).

Notification Procedure

Clinical notification – suspected cases

Cases may be suspected where there is clinical and epidemiological evidence.

Pathology Laboratories:

To notify on microbiological or serological confirmation by usual means.

Public Health Significance and Occurrence

In healthy children, chickenpox is usually a self-limiting disease requiring symptomatic treatment only. However, complications can occur in approximately 1% of cases, disease is generally more severe in adults and can cause serious and even fatal illness in immunocompromised persons of any age. ⁽¹⁾

Congenital varicella syndrome has been reported after varicella infection in the first and second trimesters of pregnancy and may result in fetal skin scarring, limb defects, ocular anomalies and neurologic malformations. There is a higher risk (2%) to the foetus when maternal infection occurs in the second trimester. ^(1,2)

Where the onset of varicella in pregnancy is between 5 days before delivery to 2 days after delivery there is a significant risk of the newborn experiencing severe varicella, estimated at 17 – 30%. ⁽³⁾

Before the universal varicella vaccination program commenced in Australia in 2005, approximately 83% of children were infected by 10-14 years of age, with about 240,000 cases, 1,500 hospitalisations and 7 – 8 deaths each year from varicella. Varicella hospitalisations in children aged 18 months to 4 years declined by 69% in the first 2.5 years following the introduction of the targeted immunisation. Herd immunity has been observed with most hospitalisations from varicella seen in children less than 18 months of age who were not eligible for vaccination. Since 2010 there has been little change in varicella hospitalisation rates; 2.1 per 100,000 population in 2013. ⁽⁴⁾

Shingles is often a serious illness in older adults and immunocompromised individuals. Shingles is uncommon before the age of 12 years, and most cases occur over the age of 50 years. ⁽⁵⁾

Clinical Features

Varicella is typically a mild childhood illness, but complications occur in approximately 1% of cases. Around 5% of cases are subclinical. ^(6,7)

The disease tends to be more severe in adults, especially in pregnant women and individuals with compromised immune systems. In immunocompromised individuals, varicella can lead to disseminated disease and may be fatal due to complications. ⁽⁸⁾

Varicella (chickenpox), caused by primary infection with varicella zoster virus, is characterised by the onset of slight fever and mild constitutional symptoms and a pruritic, (8) widespread maculopapular-vesicular rash, with lesions in varying stages of development.  Vesicular and pustular lesions are present for 3-4 days before crusting over. Lesions typically appear in crops and are more abundant on the trunk and proximal extremities. Mild, atypical and subclinical infections can occur particularly in vaccinated individuals. Secondary bacterial infections of the vesicles may cause scarring, or result in necrotising fasciitis or septicaemia, although this is rare. ⁽¹⁾

Herpes zoster (shingles) is a localised vesicular rash resulting from reactivation of latent varicella zoster virus in a period of waning immunity.  It is restricted to skin areas supplied by sensory nerves of a single or associated group of dorsal root ganglia. The rash is typically unilateral, most commonly affecting thoracic, cervical and ophthalmic dermatomes, causing severe pain. Paraesthesia is common and post-herpetic neuralgia can occur, lasting months or even years.

Occasionally permanent neurological damage, such as cranial nerve palsy or visual impairment can result. Herpes zoster is both more common and more severe in immunocompromised people.

Reservoir

Humans.

Mode of Transmission

Varicella: airborne; droplets; direct contact with nasopharyngeal secretions, or lesions of an infected person.

Herpes zoster: direct contact with lesions, vesicular fluid or indirectly through items contaminated with vesicular fluid.

Incubation Period

14 – 16 days on average (range 10 – 21 days).

Period of Communicability

The infectious period for chickenpox is typically 1 – 2 days before the onset of rash and until all the vesicles have crusted over, usually within 5 days of rash onset.

The infectious period for shingles is from the onset of vesicular rash until crusting of all lesions has occurred, usually 7-10 days.

Susceptibility and Resistance

Susceptibility to chickenpox is universal among those not previously infected or vaccinated. Susceptible people have an 80% – 90% risk of infection after household exposure to varicella.

One dose of varicella vaccine has an effectiveness estimated at 70%–90% (median 84%) for prevention of all varicella, and greater than 95% for prevention of moderate and severe disease in children followed for up to 10 years. Two doses of varicella vaccine produces an improved immune response that correlates with improved protection against disease.

Breakthrough varicella is wild-type varicella that occurs more than 42 days after vaccination. It is usually a mild case with no or mild fever, few lesions, and papules that do not generally progress to vesicles. However, breakthrough varicella infections are infectious.

Infection usually confers lifelong immunity.

Management

Cases

Investigation

Rule out varicella vaccine reaction as cause of the rash (a mild rash occurs in 1 – 5% of recipients of varicella vaccine, typically 1 – 3 weeks after vaccination). In consultation with the attending medical practitioner, ascertain any contact with anyone who may be pregnant or immunocompromised individuals.

Restriction

Chickenpox: cases should be excluded from childcare, school or work until all the vesicles have dried and crusted over – usually by the fifth day of the rash, or earlier for vaccinated children with breakthrough varicella. Vaccinated persons with varicella may develop lesions that do not crust (macules and papules only); these individuals should be isolated until no new lesions appear within a 24-hour period.

Shingles: children should be excluded from childcare or school until all vesicles have dried and crusted over. Adults may attend work dependent on a risk assessment including the location of the lesions and whether these can be covered with a waterproof dressing, and whether their work may expose those at high-risk of severe disease (see ‘high risk contacts’ below).

Treatment

There is no specific therapy for uncomplicated varicella infection. Antivirals are generally not recommended in healthy children with chickenpox but may be considered for use in individuals at risk for severe disease.

Children with chickenpox should not be given salicylates, due to an increased susceptibility to Reye’s syndrome.

Shingles: Antiviral medications (famciclovir, valaciclovir or acyclovir) may be effective in treating infections in patients with a rash less than 72 hours old. Antiviral medication may provide cases with pain relief, hasten healing of lesions and may help to reduce the incidence of postherpetic neuralgia.

High risk patients may require more intensive treatment and consultation with an infectious diseases physician is recommended.

Management of inpatients diagnosed with disseminated shingles should be discussed with the local hospital infection control team.

Counselling

The patient should be advised of the nature of the infection and its mode of transmission.

Contacts

Definition

Contacts at high risk of severe disease include:

• any person who is pregnant and not immune
• neonates whose birth parent develops varicella 7 days prior to and up to 1 month after delivery
• neonates exposed to varicella (other than from their birth parent) in the first month of life, if their birth parent is seronegative
• premature infants (born less than 28 weeks gestation or birthweight less than 1000g) exposed in hospital, regardless of their birth parent’s history of varicella
• immunocompromised individuals, particularly if known to lack detectable antibodies to varicella

Contacts at increased risk of transmission include:

• non immune healthcare workers
• non immune persons who are in enclosed environments such as prisons, boarding homes, childcare. ⁽⁹⁾

Exposure for these contacts is defined as:

• For chickenpox: living in the same household as a person with active chickenpox, or direct face-to-face contact with a person with chickenpox for at least 5 minutes or being in the same room for at least one hour. The period of infectivity is from 48 hours before the onset of rash (in the affected individual) until crusting of all lesions has occurred (usually within 5 days of rash onset). ⁽¹⁰⁾
• For shingles: living in the same household as a person with active shingles or having exposure to vesicles/vesicular fluid, from onset of rash (in the affected individual) until crusting of all lesions has occurred (usually 7-10 days). ⁽¹¹⁾

Management

Vaccination for post exposure prophylaxis:

• Post exposure vaccination can be given within 5 days after exposure, but is most effective within 3 days. (5)
• If varicella vaccine is not contraindicated, it can be offered to non-immune age-eligible children and adults who have had a significant exposure to varicella or herpes zoster and want protection against primary infection with varicella.
• A single dose of varicella vaccine can be provided to age eligible contacts under the NIP.
• Refer to Australian Immunisation Handbook | Varicella and the National Immunisation Program Schedule | Queensland for further information.

Zoster immunoglobulin (ZIG) for post exposure prophylaxis (contacts at high risk of severe disease only):

ZIG can prevent or ameliorate varicella in individuals at high risk of severe infection.

ZIG should not be delayed while waiting for varicella zoster testing in the case. ⁽⁵⁾

Neonates: Zoster immunoglobulin (ZIG) must be given as early as possible, via intramuscular injection to neonates whose mothers develop varicella 7 days prior to and up to 2 days after delivery, as neonatal mortality without ZIG is 30% in this setting.

Immunocompetent contacts at high-risk of severe infection (other than neonates): test for antibodies if practicable, as long as this does not delay ZIG administration for greater than 96 hours from their first significant exposure. Give by intramuscular injection.

Immunocompromised individuals: ZIG should be given intramuscularly within 96 hours after exposure but can be given up to 10 days after exposure. Immunocompromised contacts with recent evidence of detectable antibodies do not require ZIG, unless they have a history of transfusion or receiving intravenous immunoglobulin in the previous 3 months.⁽⁵⁾

ZIG is given intramuscularly according to the following table:^(5,12)

• The dose of ZIG recommended in the table differs from that in the product information to minimise wastage ⁽¹²⁾
• Normal human immunoglobulin can be used for the prevention of varicella if ZIG is not available
• ZIG can be ordered from Lifeblood (formally the Australian Red Cross) by consulting with the medical officer on
  07 3838 9233 or 07 3838 9010. Transportation of ZIG to a general practice surgery may have to be arranged through a private pathology company.

If the time since initial exposure has exceeded 96 hours, contacts at high-risk of severe disease should be referred to their treating specialist who may consider the use of acyclovir for prophylaxis.

Counselling:
Provide information on the nature of the infection and its mode of transmission.

For contacts at high-risk of severe infection, provide an explanation of the potential outcomes of chickenpox and the risks and benefits of ZIG.  (NB While ZIG may prevent or modify the course of chickenpox in pregnancy, it may not stop the risk of foetal infection.  Pregnant women given ZIG should be referred to their obstetrician).

Special situations

Isolation and infection prevention in hospital and residential aged care facilities:  

For recommended infection prevention precautions and isolation of patients in hospital,   refer to Table A2.5: Precautions for specific infections and conditions ⁽¹³⁾ or for residential care facilities, refer to Table 15: Precautions for diseases caused by respiratory viruses ⁽¹⁴⁾

Additional information is also available at the Australian Commission on Safety and Quality in Healthcare webpage, ‘Overview of the use of standard and transmission-based precautions’.⁽¹⁵⁾

Management of health care workers (HCW) diagnosed with varicella or shingles

Management of HCW contacts who are contacts of a confirmed case of chickenpox or disseminated shingles:

Work restrictions are generally not necessary for HCW contacts of confirmed localised shingles case. Assess any significant exposure (for example, direct unprotected contact with fluid from vesicles/lesions) for HCW who are non-immune. ⁽¹⁶⁾

Preventive Measures

All children <14 years of age are recommended to receive 2 doses of varicella-containing vaccine, with the first dose given at 18 months of age. One dose of varicella containing vaccine (MMRV) is funded through the NIP for children at 18 months of age. For details see the National Immunisation Program Schedule | Queensland. Children 12 months to <14 years of age are recommended to receive a second dose of varicella vaccine ≥4 weeks after the first dose. 2 doses of varicella-containing vaccine provide more protection and minimise the chance of breakthrough varicella in children <14 years of age.

Varicella vaccine is recommended for all non-immune adolescents aged ≥14 years and adults.

Varicella vaccine is funded through the NIP for adolescents and adults aged <20 years who have been incompletely vaccinated or do not have evidence of immunity to varicella. For details see the National Immunisation Program Schedule | Queensland. Adolescents (≥14 years of age) and adults need to receive 2 doses of varicella vaccine to achieve adequate protection from varicella.2,3 The 2 doses should be given at least 4 weeks apart. However, a longer interval between vaccine doses is acceptable.

References

1. Marin M, Bialek SR. Varicella/Herpes Zoster. In: Control of Communicable Diseases Manual [Internet]. American Public Health Association; 2015 [cited 2025 May 30]. (Control of Communicable Diseases Manual). Available from: https://ccdm.aphapublications.org/doi/abs/10.2105/CCDM.2745.151
2. Bhavsar SM, Mangat C. Congenital Varicella Syndrome [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 [cited 2025 May 30]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK568794/
3. Marin, MD M, Guris, MD D, Chaves SS, Schmid S, Seward JF. Prevention of varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP) [Internet]. National Centre; 2007 June [cited 2025 May 30] p. 1–40. Report No.: 56 (RR04). Available from: https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5604a1.htm
4. Cyra Patel, Aditi Dey, Han Wang, Peter McIntyre, Kristine Macartney, Frank Beard. Summary of National Surveillance Data on Vaccine Preventable Diseases in Australia, 2016-2018 [Internet]. Australian Government Department of Health and Aged Care; 2022 [cited 2025 July 7] p. 70–3. Report No.: Volume 26. Available from: https://www1.health.gov.au/internet/main/publishing.nsf/Content/2A15CD097063EF40CA2587CE008354F1/$File/summary_of_national_surveillance_data_on_vaccine_preventable_diseases_in_australia_2016_2018_final_report.pdf
5. Australian Technical Advisory Group on Immunisation (ATAGI). The Australian Immunisation Handbook [Internet]. Australian Government Department of Health and Aged Care; 2022. Available from: https://immunisationhandbook.health.gov.au/
6. Hamborsky J, Kroger A, Wolfe C, eds. Varicella. In: Epidemiology and prevention of vaccine-preventable diseases. 13thed. Washington, DC: Public Health Foundation; 2015.
7. Choo PW, Donahue JG, Manson JE, Platt R. The epidemiology of varicella and its complications. In: Journal of Infectious Diseases. 1995. p. 706–12.
8. Varicella. In: Plotkin’s Vaccines. 7th ed. Philadelphia, PA: Elsevier; 2018.
9. NHS Plus, Royal College of Physicians, Faculty of Occupational Medicine. Varicella zoster virus: occupational aspects of management. A national guideline [Internet]. London RCP; 2010. Available from: https://www.nhshealthatwork.co.uk/images/library/files/Clinical%20excellence/Varicella_zoster_guidelines_web_navigable.pdf
10. CDC. Infection Control. 2025 [cited 2025 May 30]. Varicella-Zoster Virus. Available from: https://www.cdc.gov/infection-control/hcp/healthcare-personnel-epidemiology-control/varicella.html
11. Yumi Hatsushika, Isao Nii, Tomohiro Taniguchi. Varicella caused by airborne transmission of a localised herpes zoster infection in a family. BMJ open. 2021;1–3.
12. Australian Product Information: Zoster Immunoglobulin-VF  AU PI 12.00 [Internet]. CSL Behring; [cited 2025 July 21]. Available from: https://labeling.cslbehring.com/PI/AU/Zoster-Immunoglobulin-VF/EN/Zoster-Immunoglobulin-VF-Product-Information.pdf
13. Australian Guidelines for the Prevention and Control of Infection in Healthcare | Australian Commission on Safety and Quality in Health Care [Internet]. [cited 2025 Apr 30]. Available from: https://www.safetyandquality.gov.au/publications-and-resources/resource-library/australian-guidelines-prevention-and-control-infection-healthcare
14. The Aged Care Infection Prevention and Control Guide: a supplementary resource for the Australian Guidelines for the Prevention and Control of Infection in Healthcare for aged care settings [Internet]. Australian Commission on Safety and Quality in Health Care; 2024 [cited 2025 Apr 30]. Available from: https://www.safetyandquality.gov.au/sites/default/files/2024-08/The-Aged-Care-Infection-Prevention-and-Control-Guide.pdf
15. Overview of the use of standard and transmission-based precautions | Australian Commission on Safety and Quality in Health Care [Internet]. [cited 2025 May 30]. Available from: https://www.safetyandquality.gov.au/publications-and-resources/resource-library/overview-use-standard-and-transmission-based-precautions
16. Queensland Infection Prevention and Control Unit. Vaccination of healthcare workers - guideline version 2.1 [Internet]. Queensland Health; 2025 [cited 2025 Apr 30]. Available from: https://www.health.qld.gov.au/__data/assets/pdf_file/0029/444872/vaccination-of-healthcare-workers.pdf