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Post-exposure prophylaxis against varicella-zoster virus infection

Post-exposure prophylaxis against varicella-zoster virus infection
Literature review current through: May 2024.
This topic last updated: Nov 29, 2021.

INTRODUCTION — Varicella-zoster virus (VZV) is one of eight herpesviruses known to cause human infection and is endemic worldwide. VZV infection causes two clinically distinct diseases: varicella (chickenpox) and herpes zoster (shingles).

Primary infection with VZV causes chickenpox, with fever and a characteristic vesicular rash. Although varicella is usually a mild, self-limited illness, it can be associated with complications, such as secondary bacterial infection, pneumonia, hepatitis, and encephalitis. Severe, sometimes fatal, complications are more common in adults, certain newborns, immunocompromised people, and pregnant women.

After primary varicella infection, VZV establishes latency in sensory ganglia, and reactivation of latent VZV can result in the painful dermatomal skin infection of herpes zoster. Herpes zoster is most commonly seen in older adults (greater than 50 years of age) and immunocompromised people. Some immunocompromised patients can develop disseminated infection (eg, multiple vesicular skin lesions in a generalized distribution distant from the dermatomes affected by the herpes zoster rash).

Patients who are susceptible to VZV infection are at risk of acquiring VZV after a significant exposure to a person with chickenpox or herpes zoster. This topic will provide an overview of the use of active immunization (varicella vaccine), passive immunization (Varizig), and antiviral post-exposure prophylaxis in nonimmune individuals after a potential exposure to VZV.

More detailed discussions of post-exposure prophylaxis for pregnant women, transplant recipients, and health care workers, as well as the use of varicella vaccine for routine immunization in children and adults, are presented elsewhere.

(See "Varicella-zoster virus infection in pregnancy", section on 'Post-exposure prophylaxis'.)

(See "Prevention of viral infections in hematopoietic cell transplant recipients", section on 'VZV postexposure prophylaxis'.)

(See "Immunizations in solid organ transplant candidates and recipients", section on 'Varicella exposure'.)

(See "Prevention and control of varicella-zoster virus in hospitals".)

(See "Vaccination for the prevention of chickenpox (primary varicella infection)".)

DEFINITIONS

Susceptibility to VZV infection — A person is considered susceptible to VZV infection if they do not meet one of these criteria for evidence of immunity [1,2]:

Written documentation of two doses separated by ≥28 days and both doses administered after age 12 months (although an interval ≥3 months between doses is recommended for children ages 1 through 12 years, the second dose is considered valid if the interval is ≥28 days) [1].

For routine varicella immunization, the first dose is recommended at age ≥12 months and the second at age 4 to 6 years. However, because vaccine failure may occur after a single dose, children <4 years of age are considered susceptible if they have not received two doses separated by ≥28 days. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Breakthrough varicella'.)

This criterion is not applicable for patients undergoing allogeneic hematopoietic cell transplant (HCT), which may ablate prior immune responses. Criteria for post-exposure against VZV in HCT recipients are discussed separately. (See "Immunizations in hematopoietic cell transplant candidates, recipients, and donors", section on 'Varicella exposure'.)

Laboratory evidence of immunity or laboratory confirmation of disease (eg, immune globulin G [IgG] antibodies to VZV; positive VZV polymerase chain reaction assay, direct fluorescent antibody staining of a specimen, or culture); commercially available antibody assays detect disease-induced antibody but may not reliably detect vaccine-induced antibody. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Post-vaccination serology' and "Diagnosis of varicella-zoster virus infection".)

Although serologic testing may provide evidence of prior infection in unvaccinated immunocompetent individuals [3], it has a limited role in determining the need for post-exposure prophylaxis because it may be unreliable for detecting immunity in immunocompromised patients and those with immunity due to vaccination. In addition, laboratory turnaround time may not allow for timely preventive interventions (ie, active immunization within five days, passive immunization within 10 days). (See 'Approach to post-exposure prophylaxis' below.)

Diagnosis or verification of prior typical varicella infection or herpes zoster infection by a health care provider. (For people reporting a history of mild or atypical varicella, verification requires documentation of an epidemiologic link to a typical case or to a laboratory-confirmed case because other diseases can mimic mild or atypical varicella [1,4,5]).

Birth in the United States before 1980 (when the prevalence of varicella was high) and not immunosuppressed, pregnant, or a health care worker. Individuals who are immunosuppressed, pregnant, or health care workers must have serologic evidence of immunity, documentation of completed immunization, or verification of typical disease because they are at increased risk of developing severe infection, increased risk of transmitting varicella to those at high risk for severe infection, and/or increased risk of being exposed to varicella.

People born outside the United States before 1980 must satisfy one of the other criteria for evidence of immunity because the prevalence of varicella in the country of origin may not be known.

Significant exposure — What constitutes a significant VZV exposure depends upon the type and severity of VZV infection in the source and the type and timing of exposure [1,6]. The risk of acquiring VZV is higher after exposure to persons with varicella than after exposure to persons with localized herpes zoster [7].

Source with varicella or disseminated herpes zoster – VZV is transmitted by inhalation of aerosolized virus from skin lesions and/or infected respiratory secretions [7,8]. (See "Clinical features of varicella-zoster virus infection: Chickenpox", section on 'Transmission and virology'.)

If the source has wild-type varicella (including varicella in a vaccinated individual [ie, breakthrough varicella]) or disseminated herpes zoster infection, we consider household contacts and those who had face-to-face indoor contact for ≥5 minutes to have had a significant exposure to VZV. In a hospital setting, this includes those patients in the same room or in adjacent hospital beds in a large ward. Other experts consider only close-proximity exposures of more than one hour to be significant [1,6]. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Breakthrough varicella'.)

Patients with varicella are generally considered infectious from one to two days before the onset of rash until all the lesions have crusted. The secondary attack rate for varicella in susceptible household contacts may be as high as 90 percent [1,9].

Patients with disseminated zoster are infectious until all the lesions have crusted.

We generally do not consider exposure to a source who developed a localized rash after varicella vaccination to be a significant exposure for immunocompetent individuals. Whether it is significant for an immunocompromised host should be considered on a case-by-case basis depending upon the level of immune suppression. Healthy vaccinated persons have a minimal risk for transmitting vaccine-associated virus to contacts, and secondary cases of varicella caused by vaccine virus are generally mild [10]. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Transmission of vaccine virus'.)

What constitutes a significant exposure in HCT recipients is discussed separately. (See "Prevention of viral infections in hematopoietic cell transplant recipients", section on 'VZV postexposure prophylaxis'.)

Source with localized herpes zoster – If the source has active localized herpes zoster, we consider the exposure to be significant when a susceptible patient has direct contact (eg, touching, hugging) with the source [1,6]; however, the risk of transmission is considerably lower with localized herpes zoster than with varicella or disseminated zoster infection.

In addition, patients may be at risk for VZV transmission if there is close, but not direct, contact with the source because airborne transmission from localized zoster may occur, but it is unclear how frequently this occurs. (See "Prevention and control of varicella-zoster virus in hospitals", section on 'Transmission from persons with zoster'.)

APPROACH TO POST-EXPOSURE PROPHYLAXIS — Management of susceptible patients depends upon the nature of the exposure, the patient's risk of developing serious disease, and whether the patient is eligible for varicella vaccine [1].

Vaccine prophylaxis for eligible patients

Who is eligible? — After a significant exposure to VZV, susceptible adults or children should be vaccinated with monovalent varicella vaccine if they are eligible; there are no data available on the combination measles, mumps, rubella, varicella vaccine for post-exposure vaccination [11]. To be eligible for vaccine prophylaxis, patients must meet all of the following criteria:

Age ≥12 months.

Not pregnant.

Not immunocompromised (eg, without primary or acquired T lymphocyte immunodeficiencies; without malignant neoplasms of the bone marrow or lymphatic system; not receiving immunosuppressive therapy); patients with HIV infection are discussed below. (See 'Patients with HIV infection' below.)

No history of severe reaction to varicella vaccine or varicella vaccine component.

Patients who received antiviral therapy with acyclovir, valacyclovir, or famciclovir within the previous 24 hours or antibody-containing immune globulin or blood product within the previous 3 to 11 months (table 1) may have a diminished response to varicella vaccine. For such patients, we individualize decisions about post-exposure vaccination after a discussion of the risks and benefits.

For children (<18 years of age) who require ongoing salicylate therapy, there is a possible risk of Reye syndrome with varicella vaccination. Although Reye syndrome was associated with the use of salicylates during wild-type varicella infection, no cases of Reye syndrome have been reported following varicella vaccine [1]. For children who require salicylate therapy, we individualize decisions about post-exposure vaccination after a discussion of the risks of vaccination versus wild-type infection.

Post-exposure prophylaxis with varicella vaccine prevents infection in 70 to 90 percent of susceptible persons and decreases severity of disease in those who develop varicella [12-18]. Several case series demonstrated that varicella vaccine is efficacious for post-exposure prophylaxis among household contacts of individuals with varicella [13-15]. In one report, 18 susceptible contacts vaccinated within three days of exposure did not develop varicella, whereas 19 unvaccinated contacts developed varicella [14].

The efficacy of varicella immunization in containing transmission was also assessed in a retrospective investigation of a varicella outbreak in 1996 (soon after the licensure of varicella vaccine), in which there were exposures comparable to household exposures [18]. Of 214 children enrolled in a day care center, 148 had no prior immunization or history of varicella. Among those who were vaccinated after the exposure, the frequency of varicella was significantly reduced in vaccinated compared with unvaccinated children (14 versus 88 percent). When varicella occurred, the clinical illness was less severe in vaccinated children and resulted in fewer days absent from the day care center. Varicella vaccine was estimated to be 86 percent effective against all forms of disease and 100 percent effective against moderate to severe disease.

Although the evidence of benefit in adults is indirect, because most studies were done in children, we administer post-exposure vaccination to adults because of their increased risk of complicated infection.

Timing

≤5 days after exposureVaricella vaccine is most effective if it is administered within five days of the exposure.

Exposed patients ≥12 months of age who were previously unvaccinated should receive the first dose within five days of the exposure. The recommended timing for the second dose varies with age [1]. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Schedules in the United States'.)

Exposed patients ≥4 years of age who have only received one dose of vaccine should receive the second dose within five days after exposure to varicella provided ≥28 days have elapsed after the first dose.

>5 days after exposure – Unvaccinated patients with a significant exposure who present >5 days after exposure can be observed for 21 days to see if disease develops, and treatment can be considered at that time. (See "Treatment of varicella (chickenpox) infection".)

Alternatively, antiviral prophylaxis may be reasonable, particularly in those who are at increased risk for complications from varicella but who do not meet criteria for varicella immune globulin (eg, adults, adolescents, children with chronic cutaneous or pulmonary disorders, secondary cases in a household). (See 'Role of antiviral prophylaxis' below.)

If varicella does not develop after 21 days, patients should be vaccinated to prevent future disease. Varicella vaccine should be administered ≥24 hours after discontinuation of antiviral therapy. (See "Vaccination for the prevention of chickenpox (primary varicella infection)".)

Eligible patients without significant exposure — Susceptible children and adults should be vaccinated against VZV even if it is determined that there was not a significant exposure, since varicella vaccination is recommended for children ≥12 months of age, adolescents, and adults without evidence of immunity [1]. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Indications and schedules'.)

Passive immunoprophylaxis — In the post-exposure setting, passive immunoprophylaxis against VZV infection typically consists of varicella-zoster immune globulin.

Target groups — Passive immunization with varicella-zoster immune globulin (eg, Varizig) is indicated for susceptible individuals after a significant exposure if they are ineligible for varicella vaccine prophylaxis, at high risk for severe infection and/or complications, and can receive immunoprophylaxis within 10 days of exposure [19,20].

Persons at high risk for severe infection and/or complications who are ineligible for varicella vaccine prophylaxis include [6,20]:

Immunocompromised patients of any age who lack evidence of immunity to VZV. This includes those with primary and acquired T lymphocyte immunodeficiencies, persons who are immunocompromised due to an underlying neoplastic disease (eg, hematologic malignancy), and individuals receiving immunosuppressive therapies. However, patients receiving monthly high-dose (≥400 mg/kg) intravenous immune globulin (IVIG) are likely to be protected if the most recent dose of IVIG was administered ≤3 weeks before exposure [20]. Patients with HIV infection are discussed below. (See 'Patients with HIV infection' below.)

Indications for Varizig in patients undergoing hematopoietic cell transplant (HCT) are discussed separately. (See "Prevention of viral infections in hematopoietic cell transplant recipients", section on 'VZV postexposure prophylaxis'.)

Pregnant women who lack evidence of immunity to VZV.

Newborns of mothers who develop varicella five days before to two days after delivery. Mother-to-child transmission of VZV can occur transplacentally in utero or via close perinatal or postnatal contact. (See "Varicella-zoster virus infection in pregnancy" and "Varicella-zoster infection in the newborn".)

Hospitalized premature infants born at ≥28 weeks of gestation whose mothers do not have evidence of immunity.

Hospitalized premature infants born at <28 weeks of gestation or who weigh ≤1000 g at birth, regardless of maternal evidence of immunity to varicella.

Given their immature T cell immunity, we also consider healthy term infants who are exposed to VZV within the first two weeks of life to be at increased risk for severe varicella if the mother does not have evidence of immunity to VZV. Other experts do not consider these infants to be candidates for passive immunoprophylaxis [6].

In several small case series, immune globulin products have reduced attack rates after exposure to varicella and modulated the severity of disease (eg, fewer lesions, less visceral involvement) [21-26]. Most studies of immunoprophylaxis have not included a placebo arm, so efficacy is inferred from historical data, which demonstrate transmission rates of greater than 90 percent after household exposure to VZV infection, and which demonstrated high complication rates in immunocompromised children with varicella. Some recipients of zoster immune globulin developed asymptomatic seroconversion, providing evidence of aborted or subclinical infection [26].

These early studies used products other than Varizig. There are limited clinical data regarding the efficacy of Varizig; however, Varizig is made by a process almost identical to varicella-zoster immune globulin (VZIG). In a study of 60 pregnant females with varicella exposure, patients were randomly assigned to either VZIG or Varizig based on time from exposure (ie, 1 to 4 days or 5 to 10 days) [22]. The efficacy and safety of the two products were similar over the 28-day period of follow-up; 29 percent developed varicella in the Varizig group compared with 42 percent in the VZIG arm. The duration following varicella exposure to the intervention did not affect efficacy.

There are no published data regarding the efficacy of Varizig in the prevention of varicella infection in HCT recipients or in HIV-infected patients.

Administration

Preferred formulation – Varizig is the preferred formulation for passive immunization. If Varizig cannot be obtained, then IVIG can be used [1].

Varizig – Varizig is a purified human varicella-zoster immune globulin made from plasma containing high levels of antivaricella antibodies (IgG) [27]. During preparation, Varizig undergoes filtration and inactivation to decrease the transmission of known viruses, such as HIV and hepatitis viruses.

Varizig is administered as a single dose intramuscularly. It is supplied in vials containing 125 international units. It is dosed according to weight as follows:

-<2 kg – 62.5 international units

-2.1 to 10 kg – 125 international units

-10.1 to 20 kg – 250 international units

-20.1 to 30 kg – 375 international units

-30.1 to 40 kg – 500 international units

-≥40 kg – 625 international units

Additional information on administration of varicella-zoster immune globulin is discussed in the drug information topic within UpToDate.

IVIG – IVIG contains antivaricella antibody titers that vary from lot to lot. The recommended dose for varicella prophylaxis is 400 mg/kg, administered as a single dose intravenously. IVIG should be considered an alternative therapy, since limited data exist regarding efficacy.

Time interval from exposure – Candidates for Varizig should receive it as soon as possible and within 10 days of exposure [20]. In an open-label study of post-exposure prophylaxis in 507 immunocompromised individuals, pregnant individuals, and newborn infants, the incidence of varicella was similar whether Varizig was administered ≤96 hours or >96 hours to 10 days after exposure (6.2 and 9.4 percent, respectively) [28].

Need for additional doses – In patients who receive immunoprophylaxis, the duration of protection is unknown but is expected to be at least three weeks. If a high-risk patient has another exposure to VZV ≥3 weeks after administration of the initial dose of immune globulin (Varizig or IVIG), another dose of Varizig should be administered [20].

Monitoring and follow-up

Monitoring for varicella – Patients who have received immunoprophylaxis need close follow-up to determine if immunoprophylaxis was effective, since 20 to 30 percent of patients may still develop infection (although it is usually attenuated) [21]. Patients who receive immunoprophylaxis should be monitored for 28 days after exposure because immunoprophylaxis may prolong the incubation period (typically 10 to 21 days) [1,6,23].

Any patient who is at high risk for severe or complicated VZV infection who develops signs and symptoms of varicella should receive prompt antiviral therapy. (See "Treatment of varicella (chickenpox) infection", section on 'Immunocompromised hosts' and "Treatment of varicella (chickenpox) infection", section on 'Pregnant women'.)

Eligibility for future varicella vaccination – Patients who receive passive immunization should be evaluated to see if they are eligible to receive varicella vaccine at a later date (eg, after delivery for pregnant women, after discontinuation of immunosuppressive therapy). However, varicella vaccine should be delayed at least five months after receipt of Varizig and eight months after receipt of IVIG (table 1) [6,27].

Role of antiviral prophylaxis — Antiviral prophylaxis with acyclovir or valacyclovir may prevent clinical varicella infection after an exposure, although efficacy data are limited. Antiviral prophylaxis is an option for patients who cannot receive varicella vaccine or immune globulin (eg, due to lack of availability, timing, or contraindications). (See 'Vaccine prophylaxis for eligible patients' above and 'Passive immunoprophylaxis' above.)

Potential target groups — Decisions regarding antiviral prophylaxis for VZV infection are made on a case-by-case basis, depending in part upon the patient's underlying condition.

Immunocompetent patients – Antiviral therapy is not routinely used for post-exposure prophylaxis in immunocompetent patients since vaccination with varicella vaccine is the preferred approach, and there are limited data regarding the efficacy of antiviral therapy for preventing disease. In addition, effective treatment can be administered to those who develop disease. (See "Treatment of varicella (chickenpox) infection".)

However, some clinicians may choose to administer antiviral prophylaxis to susceptible immunocompetent patients who cannot receive the varicella vaccine within five days of exposure (eg, due to delay in seeking treatment, limited availability, or contraindication to vaccination). (See 'Regimen' below.)

Immunocompromised patients – The decision to use acyclovir prophylaxis in immunocompromised patients must be determined on a case-by-case basis since there are few studies evaluating the efficacy of preventive antiviral therapy in this setting [29,30]. Although antiviral therapy is generally safe, it is unclear how effective it will be since patients with impaired T cell immunity may not develop an immune response to VZV and may still be at risk for infection when antiviral therapy is discontinued, as therapy is virostatic not virucidal.

Despite these concerns, some experts routinely administer antiviral therapy to immunocompromised patients if Varizig is not available. (See 'Regimen' below.)

Prevention of VZV infection in patients undergoing solid organ transplant or HCT is discussed separately. (See "Prevention of viral infections in hematopoietic cell transplant recipients", section on 'VZV postexposure prophylaxis' and "Immunizations in solid organ transplant candidates and recipients", section on 'Varicella exposure'.)

Pregnant women – The decision to use acyclovir prophylaxis in pregnant patients who cannot receive immunoprophylaxis must be determined on a case-by-case basis since there are no studies evaluating the efficacy of preventive antiviral therapy in this setting.

Regimen — For patients in whom antiviral prophylaxis is chosen, we initiate it on days 7 to 10 after exposure and continue it for one week [6,31-33]. Delaying prophylaxis until days 7 to 10 allows for the early steps of replication to occur and may allow a patient to develop some immunity without developing disease. However, some experts prefer to administer a more prolonged course in highly immunocompromised patients. (See "Prevention of viral infections in hematopoietic cell transplant recipients", section on 'VZV postexposure prophylaxis' and "Immunizations in solid organ transplant candidates and recipients", section on 'Varicella exposure'.)

Acyclovir or valacyclovir is usually used for prophylaxis. Valacyclovir is better absorbed than acyclovir and has a more convenient regimen, but its safety and efficacy have not been established for children <2 years of age. While famciclovir can be used in adults, we preferentially use valacyclovir for VZV prophylaxis because valacyclovir provides higher antiviral drug concentrations than famciclovir.

Children and adolescents:

Doses for patients with normal renal function are as follows [6,34]:

Acyclovir – 20 mg/kg per dose (maximum dose 800 mg) four times daily orally for seven days

Valacyclovir (for children ≥3 months of age) – 20 mg/kg per dose (maximum dose 1 g) three times daily orally for seven days

We check baseline renal function in children if there is concern for dehydration. Dose adjustments for individuals with reduced kidney function are found in the drug information topic within UpToDate.

Adults:

Doses for patients with normal renal function are as follows:

Acyclovir – 800 mg five times per day orally for seven days

Valacyclovir – 1 g three times per day orally for seven days

Dose adjustments for reduced kidney function are described in the drug information topics within UpToDate.

In a nonrandomized study that compared placebo with acyclovir (40 or 80 mg/kg daily in four divided doses) given on days 7 to 9 after exposure and continued for seven days in 50 children with household exposure to varicella, fewer children in the acyclovir group developed varicella (16 versus 100 percent) [35]. Among children in the acyclovir group who developed varicella, the incidence of fever and severity of skin lesions were also reduced. In a subsequent study, a seven-day course of acyclovir prophylaxis started within three days after exposure was largely ineffective compared with initiation 6 to 10 days after exposure [32].

Follow-up — We typically provide varicella vaccination one to two months after exposure to unvaccinated patients who received antiviral prophylaxis and did not develop varicella, provided they have no contraindications to vaccine. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Contraindications and precautions'.)

As an alternative, to avoid unnecessary vaccination, it may also be reasonable to obtain varicella serology four to six weeks after exposure and provide immunization to those who are nonimmune.

SPECIAL CONSIDERATIONS

Patients with HIV infection

Severely immunocompromised — For patients with HIV infection who are severely immunocompromised (eg, children with a CD4 T lymphocyte cell percentage <15 percent and adolescents and adults with CD4 count <200 cells/microL) we favor Varizig for post-exposure prophylaxis if Varizig can be administered within 10 days. This is consistent with guideline recommendations from the United States Department of Health and Human Services [31,36]. Some experts provide antiviral prophylaxis beginning five to seven days after exposure, instead of Varizig, but antiviral prophylaxis has not been formally studied in this population. (See 'Administration' above and 'Role of antiviral prophylaxis' above.)

Varicella vaccine is contraindicated in this population. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Contraindications and precautions'.)

Not severely compromised — Decisions regarding post-exposure prophylaxis in patients with HIV infection who are not severely immunocompromised are made on a case-by-case basis, given the lack of data in this population. For adolescents and adults, we generally prefer antiviral prophylaxis. (See 'Role of antiviral prophylaxis' above.)

Although varicella vaccine is not contraindicated in this population, guideline panels do not recommend varicella vaccine for post-exposure prophylaxis in patients with HIV infection because successful prophylaxis requires a rapid and robust response, which has not been studied in these patient groups [6,31,36].

Outbreak setting — Varicella vaccination is recommended for control of varicella outbreaks [1,17,18]. During an outbreak, healthy children who had only received one dose of vaccine prior to exposure should receive a second dose, provided that the age-appropriate interval has elapsed since the first dose [1]. (See "Vaccination for the prevention of chickenpox (primary varicella infection)", section on 'Schedules in the United States'.)

Persons who are vaccinated for the purpose of post-exposure prophylaxis can return to school immediately.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Varicella-zoster virus".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Beyond the Basics topics (see "Patient education: Vaccines for adults (Beyond the Basics)" and "Patient education: Vaccines for children age 7 to 18 years (Beyond the Basics)" and "Patient education: Chickenpox prevention and treatment (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

Varicella-zoster virus (VZV) infection causes two clinically distinct diseases: varicella (chickenpox) and herpes zoster (shingles). (See 'Introduction' above.)

Patients without evidence of prior varicella infection or vaccination are susceptible to VZV infection after a significant exposure. What constitutes a significant VZV exposure depends upon the type and severity of VZV infection in the source and the type and timing of exposure. The risk of acquiring VZV is higher after exposure to persons with varicella or disseminated herpes zoster than after exposure to persons with localized herpes zoster. (See 'Susceptibility to VZV infection' above and 'Significant exposure' above.)

Management of susceptible patients depends upon the nature of the exposure, the patient's risk of developing serious disease, and whether the patient is eligible for post-exposure prophylaxis with varicella vaccine.

For susceptible adults or children who are eligible for varicella vaccine and had a significant exposure within the last five days, we recommend vaccination with the monovalent varicella vaccine rather than observation or antiviral prophylaxis (Grade 1B). In observational studies, post-exposure prophylaxis with varicella vaccine prevented infection in ≥70 percent of susceptible persons and decreased severity in those who developed disease. (See 'Vaccine prophylaxis for eligible patients' above.)

For susceptible adults or children who are ineligible for varicella vaccine prophylaxis and are at greatest risk for severe infection and/or complications, we recommend varicella immune globulin (Varizig) if it can be given within 10 days of exposure (Grade 1B). (See 'Passive immunoprophylaxis' above.)

Antiviral prophylaxis is an option for patients who cannot receive varicella vaccine or immune globulin (eg, due to lack of availability, timing, or contraindications). Decisions regarding antiviral prophylaxis for VZV infection are made on a case-by-case basis, depending in part upon the patient's underlying condition. Although antiviral therapy may reduce the risk of developing varicella infection, there are minimal data on the efficacy of this approach, particularly in immunocompromised patients. (See 'Role of antiviral prophylaxis' above.)

Susceptible patients who did not receive varicella vaccine after the exposure should be reassessed for future vaccination (eg, pregnant women after delivery, immunocompromised patients no longer receiving immunosuppressive therapy). However, varicella vaccine should be delayed until at least five months after receipt of Varizig or intravenous immune globulin and 14 days after acyclovir therapy. (See 'Monitoring and follow-up' above and 'Follow-up' above.)

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Topic 8273 Version 31.0

References

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