9.11. Chickenpox (Varicella)
Updated 5 June 2026
Guidelines for Managing Chickenpox (Varicella)
This guidance is intended to assist healthcare workers in the management of patients, staff and visitors who present with symptoms suggestive of chickenpox. It is critical to implement these guidelines to prevent and control the spread of infectious diseases in an effort to avert any outbreaks.
Disease Description
Varicella, commonly known as chickenpox, is an acute, highly contagious viral illness caused by the Varicella-Zoster virus (VZV), a member of the herpesvirus family. While typically a mild and self-limiting disease in the pediatric population, VZV infection can present with increased morbidity and serious complications in adults and immunocompromised individuals. VZV remains latent in sensory ganglia following primary infection and can reactivate later in life as herpes zoster (shingles).
Modes of Transmission
| Mode | Description |
|---|---|
| Droplet or airborne transmission | Via droplets produced by coughing or sneezing during the early stages of illness. |
| Direct contact | Through direct contact with fluid from vesicular lesions in the later stages of illness. |
| Indirect contact | By freshly contaminated fomites. |
| Materno-fetal transmission | May also occur. |
Incubation Period
Ten to 21 days; commonly 14–16 days. The incubation period may be shortened in immunodeficient individuals and prolonged up to 28 days after passive immunization against varicella.
Period of Communicability
- As long as 5 days, but usually 1–2 days before onset of rash, and until all lesions have crusted over — usually about 5–7 days after rash onset.
- Contagiousness may be prolonged in individuals with altered immunity.
- Secondary attack rates in susceptible household contacts are as high as 90%.
- Susceptible individuals — defined as those without a prior history of varicella infection or vaccination — are at significant risk of acquiring infection upon exposure.
Clinical Presentation
The clinical course of varicella typically involves the following stages:
| Stage | Typical Presentation |
|---|---|
| Prodromal Phase (1–2 days) | Non-specific symptoms including fever, coryza, and malaise. |
| Exanthematous Phase | The hallmark of varicella is a pruritic, maculopapular rash that rapidly progresses through vesicular and then pustular stages before crusting over within 3–4 days. Lesions typically appear in crops, with lesions in various stages of development present simultaneously. |
| Contagious Period | Individuals are considered contagious from 1–2 days before rash onset until all lesions have crusted over, typically around 7 days after the appearance of the first vesicles. |
Complications
While generally benign in healthy children, varicella can lead to the following complications, particularly in vulnerable populations:
- Secondary bacterial skin infections
- Pneumonia, viral or bacterial
- Cerebellitis and encephalitis
- Hepatitis
- Thrombocytopenia
- Congenital varicella syndrome, if maternal infection occurs in the first 20 weeks of pregnancy
- Neonatal varicella, if maternal infection occurs within 5 days before to 2 days after delivery
High-risk groups for severe disease include: immunocompromised individuals, adults, pregnant women, neonates, and premature infants.
Diagnosis and Management
Clinical Diagnosis
Diagnosis of varicella is typically based on the characteristic clinical presentation, including history of exposure and the pathognomonic rash: crops of lesions in multiple stages simultaneously.
Laboratory Testing
- Laboratory confirmation is currently unavailable in the public sector in Saint Lucia.
- Private laboratories may send serum samples overseas for serological testing and diagnostic confirmation.
Note: Varicella in vaccinated persons, known as breakthrough disease, can be atypical — maculopapular with few or no vesicles. Maintain clinical suspicion even in vaccinated individuals.
Treatment
- Uncomplicated varicella in healthy individuals is primarily supportive and focuses on symptomatic relief.
- Avoidance of salicylates is recommended due to the risk of Reye's syndrome.
- Antiviral therapy, such as acyclovir, valacyclovir, or famciclovir, may be considered for individuals at higher risk of complications, including adults, adolescents, and immunocompromised patients, particularly if initiated within 24–72 hours of rash onset.
Isolation
Masks should be worn if there is any possibility of contact with others in the home setting. Patients should remain at home and avoid contact with susceptible individuals for at least 7 days after the onset of the rash, or until all lesions have crusted over.
Prevention Strategies
Vaccination is the most effective strategy for preventing varicella and its associated complications.
- Adult immunization: exposed susceptible adults should receive two doses of the varicella vaccine, administered at least one month apart.
- High-risk groups: vaccination is particularly important for healthcare workers, individuals working with young children, non-immune pregnant women, and susceptible contacts of immunosuppressed individuals.
Infection Control Measures
To minimize the risk of transmission, individuals with active varicella infection should:
- Remain at home and avoid contact with susceptible individuals for 7 days after rash onset, or until all lesions have crusted over.
- Practice diligent respiratory hygiene — cover the mouth and nose when coughing or sneezing.
- Refrain from sharing food, drinks, and personal items such as utensils.
Case Definitions
| Classification | Definition |
|---|---|
| Clinical Case | An illness with acute onset of generalized maculopapulovesicular rash, with classical crops of vesicles on the face/scalp spreading to trunk/limbs, with or without fever, flu-like symptoms, and general malaise, with no laboratory testing and without other apparent cause. |
| Probable Case | An acute illness with diffuse generalized maculopapulovesicular rash, lack of laboratory confirmation, and lack of epidemiologic linkage to another probable or confirmed case. |
| Confirmed Case | An acute illness with diffuse generalized maculopapulovesicular rash and either epidemiologic linkage to another probable or confirmed case, or laboratory confirmation. |
Breakthrough varicella note: In vaccinated persons who develop breakthrough varicella more than 42 days after vaccination, the disease is almost always mild, with fewer than 50 skin lesions and shorter duration of illness. The rash may be atypical, maculopapular, with few or no vesicles.
Laboratory Confirmation May Include
- Isolation of varicella virus from a clinical specimen
- Varicella antigen detected by direct fluorescent antibody (DFA) test
- Varicella-specific nucleic acid detected by PCR
- Significant rise in serum anti-varicella IgG antibody level by standard serologic assay
Outbreak Definition
| Setting | Outbreak Threshold |
|---|---|
| Childcare or school setting where children are < 13 years of age | Five or more cases occurring within a 3-week period (21 days). |
| School setting where children are ≥ 13 years of age | Three or more cases occurring within a 3-week period (21 days). |
| Residential settings and healthcare settings | Three or more cases occurring within a 3-week period (21 days). |
Management of Contacts
Evidence of Immunity
Any of the following constitutes evidence of immunity:
- Documentation of two doses of chickenpox vaccine administered at least 28 days apart, with the first dose given no earlier than the first birthday.
- Laboratory evidence of immunity to chickenpox or laboratory confirmation of disease.
- Diagnosis or verification of a history of chickenpox or shingles by a healthcare provider.
A person is deemed a contact if they have been within 3 feet for more than 1 hour in the same room, such as a classroom or cafeteria, of an infected person during the infectious period, or are a household contact.
| Contact Category | Recommended Management |
|---|---|
| Unvaccinated contacts without evidence of immunity | Individuals aged 12 months and older should receive their first varicella vaccination within 5 days of exposure. Vaccination within 3 days is optimal. |
| Fully vaccinated contacts or those with evidence of immunity | No exclusion or restrictions are recommended. |
| Unvaccinated contacts who refuse vaccination | Advise monitoring for onset of symptoms. No quarantine is necessary. |
VariZIG availability: VariZIG is currently unavailable in Saint Lucia as of 2025. Clinicians should contact the Epidemiology Unit for guidance on alternative management for high-risk contacts.
Management of Breakthrough Disease
- Varicella in vaccinated persons, or breakthrough disease, is a varicella-like rash occurring more than 42 days after vaccination.
- Susceptible persons can develop chickenpox after exposure to breakthrough disease.
- Persons with breakthrough disease should be excluded from school/work settings until no new lesions have appeared within a 24-hour period.
Residential Institutions and Healthcare Settings
- Airborne and contact precautions are recommended for patients with chickenpox until all lesions have crusted, usually 4–7 days after rash onset.
- Employees with chickenpox should be placed on leave immediately.
- Assess immunization status of all exposed patients and healthcare workers, including persons involved in direct patient care and those who work in the patient care setting.
- Only immune staff should care for patients with chickenpox infection.
- Exposed, susceptible patients should be placed under airborne and contact precautions from the 8th through the 21st day after exposure to the index patient, or 28 days for those who received VariZIG.
- Exposed healthcare workers who have received 2 doses of vaccine should be monitored daily during days 8–21 after exposure by an infection control nurse to determine clinical status, including daily screening for fever, skin lesions, and systemic symptoms.
- Exposed healthcare workers who have received 1 dose of vaccine should receive the second dose within 3–5 days post-exposure, provided 4 weeks have elapsed after the first dose. After vaccination, management is similar to 2-dose vaccine recipients.
- Healthcare workers who do not receive a second dose, or who received it more than 5 days after exposure, should be excluded from work for days 8–21 after exposure.
Notification and Reporting
Chickenpox (Varicella) is a NOTIFIABLE DISEASE in Saint Lucia. ALL suspected and confirmed cases MUST be reported to the Epidemiology Unit at the Ministry of Health. Outbreaks must be reported within 24 hours of identification.
Key Messages for Healthcare Workers
- Maintain clinical suspicion for varicella in any patient presenting with a pruritic, vesicular rash in crops, including vaccinated individuals who may present atypically.
- Do NOT administer aspirin or salicylate-containing products to any patient with suspected or confirmed varicella.
- Initiate antiviral therapy, such as acyclovir, early — within 24–72 hours of rash onset — for adults, adolescents, and immunocompromised patients.
- Enforce airborne and contact precautions immediately for any patient with active varicella in a healthcare setting.
- Report all suspected and confirmed cases and outbreaks to the Epidemiology Unit.
Reference List
- Centers for Disease Control and Prevention (2024). Chickenpox (Varicella): For Healthcare Professionals. Available from: https://www.cdc.gov/chickenpox/hcp/index.html
- Ontario Public Health Standards (2022). Infectious Disease Protocol — Chickenpox (Varicella). Available from: https://files.ontario.ca/moh-ophs-chickenpox-varicella-en-2022.pdf
- Centers for Disease Control and Prevention. Strategies for the Control and Investigation of Varicella Outbreaks. Lopez A, Marin M. Available from: https://www.cdc.gov/chickenpox/hcp/outbreak-control.html
- World Health Organization (2023). Varicella and Herpes Zoster Vaccines: WHO Position Paper. Weekly Epidemiological Record, 89(25), 265–288.