Varicella-zoster virus: Difference between revisions

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−
== Background ==
 +
==Background==
   
−
=== Microbiology ===
 +
===Microbiology===
−
* dsDNA virus in the Alphaherpesvirus family, related to HSV
  
−
* Key glycoproteins
  
−
** gB II target of neutralizing antibodies like VZIg
  
−
** gC gp IV not essential
  
−
** gE gp I binds Fc IgG
  
−
** gH gp III fusion function
  
−
** gL glycosylation
  
   
  +
*dsDNA virus in the ''Alphaherpesvirinae'' subfamily within the [[Herpesviridae]] family, related to HSV
−
=== Epidemiology ===
  
  +
*Key glycoproteins
−
* Varicella is more late winter or spring in temperate climates, often corresponds to school year
  
  +
**gB II target of neutralizing antibodies like VZIg
−
* Acquired by 5-10 years old in temperate climates
  
  +
**gC gp IV not essential
−
** In tropical climates, more susceptibility in adults
  
  +
**gE gp I binds Fc IgG
−
* Incubation period is 21 days
  
  +
**gH gp III fusion function
−
* Infectiousness lasts from 24h before rash (around time of fever) to the final crusting
  
  +
**gL glycosylation
−
* Transmitted airborne, respiratory secretions; ''not'' transmitted on fomites
  
   
−
=== Pathophysiology ===
 +
===Epidemiology===
−
* Transmitted by respiratory route
  
−
* Primary viremia infects liver and RES (~14 days)
  
−
* Secondary viremia causes dissemination to skin
  
   
  +
*Varicella is more late winter or spring in temperate climates, often corresponds to school year
−
== Clinical Presentation ==
  
  +
*Acquired by 5-10 years old in temperate climates
  +
**In tropical climates, more susceptibility in adults
  +
*Incubation period is [[Usual incubation period::10 to 21 days]]
  +
*Infectiousness lasts from 24h before rash (around time of fever) to the final crusting
  +
*Transmitted airborne, respiratory secretions; ''not'' transmitted on fomites
   
  +
===Pathophysiology===
−
=== Primary infection (varicella) ===
  
−
* Primary infection usually benign in childhood
  
−
* Primary infection can be severe in adolescents, adults, and immunocompromised hosts
  
−
* New vesicle formation stops within 4 days
  
−
* Presentation modified by prior vaccination
  
−
** Less severe, fewer vesicles, less classic rash
  
−
* Vaccine-associated: can also get infected by the vaccine strain itself
  
   
  +
*Transmitted by respiratory route
−
==== Differential Diagnosis ====
  
  +
*Primary viremia infects liver and RES (~14 days)
−
* [[Enterovirus]]
  
  +
*Secondary viremia causes dissemination to skin
−
* [[Staphylococcus aureus]]
  
−
* Drug reactions
  
−
* Contact dermatitits
  
−
* Eczema herpeticum
  
−
* Insect bites
  
   
  +
==Clinical Manifestations==
−
==== Breakthrough ====
  
−
* 20% of vaccinated children still acquire varicella
  
−
* Milder, fewer sequelae
  
   
−
==== Sequelae ====
 +
===Primary Infection (Varicella)===
−
* SSTI: invasive GAS including nec fasc
  
−
* Hepatitis, especially in immunocompromised, transplant, and AIDS (can be severe)
  
−
* Diarrhea, pharyngitis, otitis, nephritis, transient arthritis, myocarditis, ...
  
−
* Neurologic
  
−
** Acute cerebellar ataxia
  
−
** Diffuse encephalitis
  
−
** Aseptic meningitis, transverse myelitis, strokes
  
−
* Reye syndrome: vomiting, excitability, delirium, and coma
  
−
** Secondary to varicella and concomitant aspirin
  
−
* Respiratory: pneumonitis can be severe
  
−
** Typically develops days after rash
  
−
** Consider [[Is treated by::acyclovir]] ± [[prednisone]]
  
   
  +
*Primary infection usually benign in childhood
−
==== High-risk populations ====
  
  +
*Primary infection can be severe in adolescents, adults, and immunocompromised hosts
−
* Pregnancy
  
  +
*New vesicle formation stops within 4 days
−
** Spontaneous abortions, IUFD, prematurity
  
  +
*Presentation modified by prior vaccination
−
** Congenital varicella syndrome
  
  +
**Less severe, fewer vesicles, less classic rash
−
*** Highest risk <20 weeks
  
  +
*Vaccine-associated: can also get infected by the vaccine strain itself
−
*** Cutaneous defects, cicatral scarring and limb atrophy
  
−
*** Microcephaly, autonomic dysfunction
  
−
** If primary varicella 5 days before to 2 days after delivery, high risk of mortality
  
−
* Immune-compromised hosts
  
−
** Can have progressive disease with prolonged lesions and multiorgan infection
  
   
  +
====Differential Diagnosis====
−
=== Herpes zoster (shingles) ===
  
   
  +
*[[Enterovirus]]
−
* Varicella reactivation from dorsal root ganglia
  
  +
*[[Staphylococcus aureus]]
−
* Dermatomal
  
  +
*Drug reactions
−
* Herpes ophthalmaticus (CN V1)
  
  +
*Contact dermatitits
−
* Ramsay-Hunt syndrome
  
  +
*Eczema herpeticum
−
* Post-herpetic neuralgia
  
  +
*Insect bites
   
−
==== Risk factors ====
 +
====Breakthrough====
   
  +
*20% of vaccinated children still acquire varicella
−
* Rising age predict zoster as well as postherpetic neuralgia
  
  +
*Milder, fewer sequelae
−
** 50% by age 85 years
  
−
* Post-surgery
  
−
* [[HIV]] (even with normal CD4)
  
−
* Transplant (HSCT > SOT)
  
   
−
==== Immunocompromized ====
 +
====Sequelae====
   
  +
*[[SSTI]] caused by secondary bacterial infection with invasive [[GAS]], and can including [[necrotizing fasciitis]]
−
* May become disseminated
  
  +
*[[Hepatitis]], especially in immunocompromised, transplant, and advanced HIV (can be severe)
−
* Can become chronic with episodic viremia
  
  +
*[[Diarrhea]], [[pharyngitis]], [[otitis]], [[nephritis]], transient [[arthritis]], [[myocarditis]], ...
−
* Prophylaxis
  
  +
*Neurologic
−
** HSCT: prophylax with valacyclovir for 1+ year following transplant (longer if GVHD)
  
  +
**Acute cerebellar ataxia
−
** SOT: 3-6 mo after transplant and for duration of lymphodepletion
  
  +
**Diffuse encephalitis
  +
**Aseptic meningitis, transverse myelitis, strokes
  +
*[[Reye syndrome]]: vomiting, excitability, delirium, and coma
  +
**Secondary to varicella and concomitant aspirin
  +
*Respiratory: [[pneumonitis]] can be severe
  +
**Typically develops days after rash
  +
**Consider [[Is treated by::acyclovir]] ± [[prednisone]]
   
  +
====High-Risk Populations====
−
== Diagnosis ==
  
   
  +
*Certain populations are at higher risk for severe complications
−
* PCR most common, sensitive and specific, can be tissue, serum, CSF, saliva, etc
  
  +
*Pregnancy
−
* Multinucleated giant cells on histology
  
  +
**[[Spontaneous abortion]], [[IUFD]], [[prematurity]]
−
* Cell culture
  
  +
**[[Congenital varicella syndrome]]
−
* Serology
  
  +
***Highest risk <20 weeks
  +
***Cutaneous defects, cicatral scarring and limb atrophy
  +
***Microcephaly, autonomic dysfunction
  +
**If primary varicella 5 days before to 2 days after delivery, high risk of mortality
  +
*Immune-compromised hosts
  +
**Can have progressive disease with prolonged lesions and multiorgan infection
   
  +
===Herpes Zoster (Shingles)===
−
== Management ==
  
−
* [[Is treated by::Valacyclovir]] preferred to [[Is treaed by::acyclovir]]
  
−
** Main side effect of valacylovir is headache
  
   
  +
*Varicella reactivation from dorsal root ganglia
−
=== Normal host ===
  
  +
*Typically a dermatomal distribution
−
* '''Primary varicella'''
  
  +
*Herpes ophthalmaticus (CN V1)
−
** Simple VZV infection, start ASAP (<72 hours) after onset of rash if going to treat; or, don't treat
  
  +
*Ramsay-Hunt syndrome
−
** If higher risk or severe sequelae, more likely to treat
  
  +
*Post-herpetic neuralgia
−
** 5 days in normal host
  
−
* '''Zoster'''
  
−
** Start treatment within 72 hours to reduce new lesions (doesn't affect PHN)
  
   
  +
====Risk Factors====
−
=== Immunocompromised host ===
  
−
* '''Primary varicella''': start with IV [[Is treaed by::acyclovir]], then step down to oral [[Is treaed by::valacyclovir]]
  
−
* '''Zoster''': start with IV [[Is treaed by::acyclovir]], then PO with close followup, until no new lesions for 2 days (minimum 7 days)
  
−
* '''Pregnancy''': treat zoster if more than 50 lesions
  
−
* '''Ophthalmic zoster''' should be treated (involve Ophtho)
  
−
* '''Acute retinal necrosis''': IV [[Is treaed by::acyclovir]] for 10 to 14 days, with steroids (involve Ophtho)
  
−
* '''Ramsay Hunt syndrome''': PO antiviral with prednisone
  
   
  +
*Rising age predict zoster as well as postherpetic neuralgia
−
=== Post-exposure management ===
  
  +
**50% by age 85 years
−
* Identify contacts: very long list, includes anyone with 5 minutes of face-to-face time, adjacent rooms or beds, ...
  
  +
*Post-surgery
−
** Infectious 1-2 days before onset of rash
  
  +
*[[HIV]] (even with normal CD4)
−
* '''Isolation''' of contacts
  
  +
*Transplant (HSCT > SOT)
−
** Exposed patients without evidence of immunity should be discharge as soon as possible
  
−
** If not discharged, isolate them starting 8 days from exposure (in airborne)
  
−
** Duration of isolation 21 days; if VZIg (or IVIg), extend duration of isolation to 28 days
  
−
** i.e. day 8 to 21 if no VZIg, day 8 to 28 if VZIg
  
−
* '''Post-exposure vaccination'''
  
−
** Recommended for everyone, assuming that there is no documented immunity and there is no contraindication
  
−
** Within 3-5 days post-exposure
  
−
* '''VZIg''' (or IVIg, if VZIg not available)
  
−
** Indications
  
−
*** Immune-compromised without evidence of immunity
  
−
*** Pregnant woman without evidence of immunity
  
−
*** Child of mother she had primary chicken pox 5 days before to 2 days after delivery
  
−
*** Preterm >28 days without evidence of immunity
  
−
*** Preterm <28 weeks gestation
  
−
*** HSCT who have not had their vaccine post-transplant
  
−
** Start within 10 days after exposure
  
   
−
=== Vaccination ===
 +
====Disseminated Zoster====
   
  +
*May become disseminated in immunocompromised patients, typically after transplantation
−
=== Varicella ===
  
  +
**Involvement of visceral organs, or
−
* Live attenuated varicella vaccine at 12 months then again at 4 to 6 years
  
  +
**Multidermatomal involving 3 or more dermatomes
−
* Can use for PEP if within 3 days of exposure to reduce severity and duration
  
  +
*Can become chronic with episodic viremia
−
* Live vaccine, so must be at least 12 months
  
  +
*Prophylaxis
−
* Two doses 90% effective, though can wane over time
  
  +
**HSCT: prophylax with [[valacyclovir]] for 1+ year following transplant (longer if GVHD)
−
* Adverse effects
  
  +
**SOT: 3-6 mo after transplant and for duration of lymphodepletion
−
** Injection site reaction 20%
  
−
** Rash with 2-5 lesions (1-3%) or generalized within 1 month (3-5%); it is infectious
  
−
** Febrile seizures: MMR + VZV at 12 months has higher risk of febrile seizures
  
−
** Disseminated, including meningitis
  
−
* See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-24-varicella-chickenpox-vaccine.html Canadian Immunization Guide]
  
   
−
=== Zoster ===
 +
==Diagnosis==
  +
−
* '''Shingrix''' (non-live recombinant; 2 doses, 6 months apart; '''more effective''') and '''Zostavax''' (live attenuated, 1 dose)
  
  +
*PCR most common, sensitive and specific, can be tissue, serum, CSF, saliva, etc
−
** If Zostavax, give Shingrix after 7 years as a booster
  
  +
*Multinucleated giant cells on histology
−
** If recent zoster, wait three years after an episode
  
  +
*Cell culture
−
** Zostavax-induced immunity wanes fairly quickly while Shingrix-induced immunity appears to be much more durable
  
  +
*Serology
−
* Indicated in all people ≥50 years old to reduce risk of zoster and PHN
  
  +
−
** History of VZV or vaccination doesn't matter, everyone can get it
  
  +
==Management==
−
* See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-8-herpes-zoster-(shingles)-vaccine.html Canadian Immunization Guide]
  
  +
  +
*[[Is treated by::Valacyclovir]] preferred to [[Is treated by::acyclovir]]
  +
**Main side effect of valacylovir is headache
  +
**Ideally started early, within 72 hours of symptom onset
  +
  +
===Normal host===
  +
  +
*'''Primary varicella'''
  +
**Simple VZV infection, start ASAP (<72 hours) after onset of rash if going to treat; or, don't treat
  +
**If higher risk or severe sequelae, more likely to treat
  +
**5 days in normal host
  +
*'''Zoster'''
  +
**Start treatment within 72 hours to reduce new lesions (doesn't affect PHN)
  +
  +
===Immunocompromised host===
  +
  +
*'''Primary varicella''': start with IV [[Is treated by::acyclovir]], then step down to oral [[Is treaed by::valacyclovir]]
  +
*'''Herpes zoster''': start with IV [[Is treated by::acyclovir]], then PO with close followup, until no new lesions for 2 days (minimum 7 days)
  +
*'''Pregnancy''': treat zoster if more than 50 lesions
  +
*'''Ophthalmic zoster''' should be treated (involve Ophtho)
  +
*'''Acute retinal necrosis''': IV [[Is treated by::acyclovir]] for 10 to 14 days, with steroids (involve Ophtho)
  +
*'''Ramsay Hunt syndrome''': PO [[Is treated by::acyclovir]] or [[Is treated by::valacyclovir]], with prednisone
  +
*'''CNS disease''': IV [[Is treated by::acyclovir]] for 10 to 14 days
  +
  +
==Prevention==
  +
  +
===Infection Prevention and Control===
  +
  +
*Airborne isolation required for primary varicella and disseminated zoster
  +
  +
===Post-Exposure Management===
  +
  +
*Identify contacts: very long list, includes anyone with 5 minutes of face-to-face time, adjacent rooms or beds, ...
  +
**Infectious 1-2 days before onset of rash
  +
*'''Isolation''' of contacts
  +
**Exposed patients without evidence of immunity should be discharge as soon as possible
  +
**If not discharged, isolate them starting 8 days from first exposure (in airborne)
  +
**Duration of isolation 21 days; if VZIg (or IVIg), extend duration of isolation to 28 days
  +
**i.e. day 8 to 21 if no VZIg, day 8 to 28 if VZIg
  +
*'''Post-exposure vaccination'''
  +
**Recommended for '''all susceptible''' exposed individuals, assuming that there is no documented immunity and there is no contraindication
  +
**Within 3-5 days post-exposure to prevent disease (or any time because they need vaccination anyway)
  +
*'''VZIg''' (or IVIg, if VZIg not available)
  +
**Indicated ''only'' for '''susceptible''' individuals with significant '''exposure''' who are at '''high risk''' of poor outcome and have a '''contraindication''' to vaccination
  +
***That is, anyone who is already fully vaccinated or is eligible for vaccination is ineligible for VZIg
  +
***If their serostatus is unknown and can be checked within 96 hours, then do that first (except for patients with HSCT, who get immunized regardless)
  +
**High risk groups include:
  +
***Neonates exposed to mother who had onset of varicella 5 days before to 2 days after delivery
  +
***Infant in NICU who is [[preterm]] <28 weeks or weighs <1000 g, regardless of maternal immunity
  +
***[[Pregnancy]] (again, only if susceptible)
  +
***Immunocompromised individuals, including [[HIV]] with CD4 <200 or <15%
  +
***[[HSCT]] who have not completed their vaccines post-transplant, regardless of prior immunity
  +
**Significant contact includes:
  +
***Continuous household contact
  +
***Indoors for more than 1 hour, including same hospital room
  +
***15 minutes face-to-face contact
  +
***Touch lesions, clothes, or bedsheets
  +
**Start within 4 days of exposure to prevent disease, or within 10 days of exposure to attenuate it
  +
  +
===Vaccination===
  +
  +
====Varicella====
  +
  +
*Live attenuated varicella vaccine at 12 months then again at 4 to 6 years
  +
*Can use for PEP if within 3 days of exposure to reduce severity and duration
  +
*Live vaccine, so must be at least 12 months
  +
*Two doses 90% effective, though can wane over time
  +
*Adverse effects
  +
**Injection site reaction 20%
  +
**Rash with 2-5 lesions (1-3%) or generalized within 1 month (3-5%); it is infectious
  +
**Febrile seizures: MMR + VZV at 12 months has higher risk of febrile seizures
  +
**Disseminated, including meningitis
  +
*See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-24-varicella-chickenpox-vaccine.html Canadian Immunization Guide]
  +
  +
====Zoster====
  +
  +
*Vaccination prevents episodes of herpes zoster (HZ) as well as decreasing post-herpetic neuralgia (PHN)
  +
*Indicated in all people ≥50 years old to reduce risk of zoster and PHN
  +
**History of VZV or vaccination doesn't matter, everyone should get it
  +
*In Canada, preferentially use Shingrix, as it is more effective than the live vaccine
  +
**If received Zostavax, wait at least 1 year before giving a booster with Shingrix
  +
**If recent episode of HZ, wait at least 1 year before vaccinating
  +
*See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-8-herpes-zoster-(shingles)-vaccine.html Canadian Immunization Guide]
  +
  +
{| class="wikitable"
  +
!
  +
!Recombinant
  +
!Live Attenuated
  +
|-
  +
|Brand Name
  +
|Shingrix
  +
|Zostavax II
  +
|-
  +
|Schedule
  +
|2 doses, 2-6 months apart
  +
|1 dose
  +
|-
  +
|Effectiveness
  +
|>90% for HZ and PHN, and persists over time
  +
|50-70% for HZ and 70% for PHL, but decreases significantly by 5 years
  +
|}
  +
  +
=== Antiviral Prophylaxis ===
  +
  +
* [[Acyclovir]] 400 mg p.o. twice daily (though range is 200 mg once daily to 300 mg three ties daily)
  +
* [[Valacyclovir]] 500 mg p.o. daily (or 250 mg daily)
  +
* [[Famciclovir]] 500 mg p.o. daily
   
 
[[Category:Herpesviridae]]
  
[[Category:Herpesviridae]]

Latest revision as of 09:43, 16 September 2024

Background

Microbiology

  • dsDNA virus in the Alphaherpesvirinae subfamily within the Herpesviridae family, related to HSV
  • Key glycoproteins
    • gB II target of neutralizing antibodies like VZIg
    • gC gp IV not essential
    • gE gp I binds Fc IgG
    • gH gp III fusion function
    • gL glycosylation

Epidemiology

  • Varicella is more late winter or spring in temperate climates, often corresponds to school year
  • Acquired by 5-10 years old in temperate climates
    • In tropical climates, more susceptibility in adults
  • Incubation period is 10 to 21 days
  • Infectiousness lasts from 24h before rash (around time of fever) to the final crusting
  • Transmitted airborne, respiratory secretions; not transmitted on fomites

Pathophysiology

  • Transmitted by respiratory route
  • Primary viremia infects liver and RES (~14 days)
  • Secondary viremia causes dissemination to skin

Clinical Manifestations

Primary Infection (Varicella)

  • Primary infection usually benign in childhood
  • Primary infection can be severe in adolescents, adults, and immunocompromised hosts
  • New vesicle formation stops within 4 days
  • Presentation modified by prior vaccination
    • Less severe, fewer vesicles, less classic rash
  • Vaccine-associated: can also get infected by the vaccine strain itself

Differential Diagnosis

Breakthrough

  • 20% of vaccinated children still acquire varicella
  • Milder, fewer sequelae

Sequelae

High-Risk Populations

  • Certain populations are at higher risk for severe complications
  • Pregnancy
  • Immune-compromised hosts
    • Can have progressive disease with prolonged lesions and multiorgan infection

Herpes Zoster (Shingles)

  • Varicella reactivation from dorsal root ganglia
  • Typically a dermatomal distribution
  • Herpes ophthalmaticus (CN V1)
  • Ramsay-Hunt syndrome
  • Post-herpetic neuralgia

Risk Factors

  • Rising age predict zoster as well as postherpetic neuralgia
    • 50% by age 85 years
  • Post-surgery
  • HIV (even with normal CD4)
  • Transplant (HSCT > SOT)

Disseminated Zoster

  • May become disseminated in immunocompromised patients, typically after transplantation
    • Involvement of visceral organs, or
    • Multidermatomal involving 3 or more dermatomes
  • Can become chronic with episodic viremia
  • Prophylaxis
    • HSCT: prophylax with valacyclovir for 1+ year following transplant (longer if GVHD)
    • SOT: 3-6 mo after transplant and for duration of lymphodepletion

Diagnosis

  • PCR most common, sensitive and specific, can be tissue, serum, CSF, saliva, etc
  • Multinucleated giant cells on histology
  • Cell culture
  • Serology

Management

  • Valacyclovir preferred to acyclovir
    • Main side effect of valacylovir is headache
    • Ideally started early, within 72 hours of symptom onset

Normal host

  • Primary varicella
    • Simple VZV infection, start ASAP (<72 hours) after onset of rash if going to treat; or, don't treat
    • If higher risk or severe sequelae, more likely to treat
    • 5 days in normal host
  • Zoster
    • Start treatment within 72 hours to reduce new lesions (doesn't affect PHN)

Immunocompromised host

  • Primary varicella: start with IV acyclovir, then step down to oral valacyclovir
  • Herpes zoster: start with IV acyclovir, then PO with close followup, until no new lesions for 2 days (minimum 7 days)
  • Pregnancy: treat zoster if more than 50 lesions
  • Ophthalmic zoster should be treated (involve Ophtho)
  • Acute retinal necrosis: IV acyclovir for 10 to 14 days, with steroids (involve Ophtho)
  • Ramsay Hunt syndrome: PO acyclovir or valacyclovir, with prednisone
  • CNS disease: IV acyclovir for 10 to 14 days

Prevention

Infection Prevention and Control

  • Airborne isolation required for primary varicella and disseminated zoster

Post-Exposure Management

  • Identify contacts: very long list, includes anyone with 5 minutes of face-to-face time, adjacent rooms or beds, ...
    • Infectious 1-2 days before onset of rash
  • Isolation of contacts
    • Exposed patients without evidence of immunity should be discharge as soon as possible
    • If not discharged, isolate them starting 8 days from first exposure (in airborne)
    • Duration of isolation 21 days; if VZIg (or IVIg), extend duration of isolation to 28 days
    • i.e. day 8 to 21 if no VZIg, day 8 to 28 if VZIg
  • Post-exposure vaccination
    • Recommended for all susceptible exposed individuals, assuming that there is no documented immunity and there is no contraindication
    • Within 3-5 days post-exposure to prevent disease (or any time because they need vaccination anyway)
  • VZIg (or IVIg, if VZIg not available)
    • Indicated only for susceptible individuals with significant exposure who are at high risk of poor outcome and have a contraindication to vaccination
      • That is, anyone who is already fully vaccinated or is eligible for vaccination is ineligible for VZIg
      • If their serostatus is unknown and can be checked within 96 hours, then do that first (except for patients with HSCT, who get immunized regardless)
    • High risk groups include:
      • Neonates exposed to mother who had onset of varicella 5 days before to 2 days after delivery
      • Infant in NICU who is preterm <28 weeks or weighs <1000 g, regardless of maternal immunity
      • Pregnancy (again, only if susceptible)
      • Immunocompromised individuals, including HIV with CD4 <200 or <15%
      • HSCT who have not completed their vaccines post-transplant, regardless of prior immunity
    • Significant contact includes:
      • Continuous household contact
      • Indoors for more than 1 hour, including same hospital room
      • 15 minutes face-to-face contact
      • Touch lesions, clothes, or bedsheets
    • Start within 4 days of exposure to prevent disease, or within 10 days of exposure to attenuate it

Vaccination

Varicella

  • Live attenuated varicella vaccine at 12 months then again at 4 to 6 years
  • Can use for PEP if within 3 days of exposure to reduce severity and duration
  • Live vaccine, so must be at least 12 months
  • Two doses 90% effective, though can wane over time
  • Adverse effects
    • Injection site reaction 20%
    • Rash with 2-5 lesions (1-3%) or generalized within 1 month (3-5%); it is infectious
    • Febrile seizures: MMR + VZV at 12 months has higher risk of febrile seizures
    • Disseminated, including meningitis
  • See the Canadian Immunization Guide

Zoster

  • Vaccination prevents episodes of herpes zoster (HZ) as well as decreasing post-herpetic neuralgia (PHN)
  • Indicated in all people ≥50 years old to reduce risk of zoster and PHN
    • History of VZV or vaccination doesn't matter, everyone should get it
  • In Canada, preferentially use Shingrix, as it is more effective than the live vaccine
    • If received Zostavax, wait at least 1 year before giving a booster with Shingrix
    • If recent episode of HZ, wait at least 1 year before vaccinating
  • See the Canadian Immunization Guide
Recombinant Live Attenuated
Brand Name Shingrix Zostavax II
Schedule 2 doses, 2-6 months apart 1 dose
Effectiveness >90% for HZ and PHN, and persists over time 50-70% for HZ and 70% for PHL, but decreases significantly by 5 years

Antiviral Prophylaxis

  • Acyclovir 400 mg p.o. twice daily (though range is 200 mg once daily to 300 mg three ties daily)
  • Valacyclovir 500 mg p.o. daily (or 250 mg daily)
  • Famciclovir 500 mg p.o. daily
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