What is the recommended management and prophylaxis for varicella (chickenpox) in healthy children, adolescents, adults, pregnant women, newborns, and immunocompromised patients?

Chickenpox Management

All individuals without evidence of immunity should receive two doses of varicella vaccine, with specific timing based on age, and high-risk exposed individuals require varicella zoster immune globulin (VariZIG) for post-exposure prophylaxis within 10 days of exposure. 1

Routine Vaccination Strategy

Healthy Children (12 months - 12 years)

• First dose at 12-15 months of age administered subcutaneously (0.5 mL) 1
• Second dose at 4-6 years (before school entry), though it may be given earlier if ≥3 months have elapsed since the first dose 1
• If the second dose is inadvertently given >28 days after the first (but <3 months), it remains valid and need not be repeated 1
• Two-dose efficacy reaches 98.3% compared to 94.4% with single dose, reducing breakthrough disease risk 3.3-fold 1

Adolescents and Adults (≥13 years)

• Two 0.5-mL doses given 4-8 weeks apart subcutaneously for all without evidence of immunity 1
• Only single-antigen varicella vaccine is approved for this age group (MMRV not licensed for ≥13 years) 1
• Priority groups requiring special consideration include: healthcare personnel, household contacts of immunocompromised persons, teachers, daycare employees, college students, military personnel, inmates, and nonpregnant women of childbearing age 1

Catch-Up Vaccination

• All individuals who previously received only one dose should receive a second dose 1
• Minimum interval: 3 months for children <12 years; 4 weeks for persons ≥13 years 1
• The catch-up dose may be administered at any interval longer than the minimum recommended 1

Post-Exposure Prophylaxis

VariZIG Administration

VariZIG should be administered as soon as possible after exposure, but can be given up to 10 days post-exposure (extended from the previous 96-hour window). 1, 2

Dosing: 125 IU per 10 kg body weight, maximum 625 IU (five vials), minimum 62.5 IU for infants ≤2.0 kg 1

High-Risk Groups Requiring VariZIG

Immunocompromised patients without evidence of immunity 1, 3

• Includes those on steroid therapy >2 mg/kg body weight or total of 20 mg/day prednisone equivalent 1
• Varicella incidence after VariZIG administration: 4.5% in this population 2

Pregnant women without evidence of immunity 1, 4

• Varicella during first two trimesters can cause congenital varicella syndrome 1
• Routine antenatal screening for immunity is recommended 1
• Varicella incidence after VariZIG: 7.3% 2
• Postpartum vaccination should be given to those without immunity 1

Newborns and premature infants 1, 4

• Newborns whose mothers develop varicella 5 days before to 2 days after delivery 1
• Premature infants ≥28 weeks gestation if mother lacks immunity 1
• All premature infants <28 weeks gestation or ≤1,000 g at birth, regardless of maternal immunity 1
• Varicella incidence after VariZIG in infants: 11.5% 2

Post-Exposure Vaccination (Alternative for Eligible Individuals)

• Healthy, non-pregnant individuals without evidence of immunity who are vaccine-eligible should receive varicella vaccine within 3-5 days of exposure 3
• This may prevent infection or attenuate disease severity 3, 5
• After VariZIG administration, wait ≥5 months before administering varicella vaccine 1

Active Disease Management

Monitoring After VariZIG

• Observe patients for 28 days post-exposure (extended incubation period with VariZIG) 1
• Institute antiviral therapy immediately if signs or symptoms develop 1

Antiviral Treatment

Oral acyclovir prophylaxis should be considered for susceptible pregnant women exposed to VZV who did not receive VariZIG or have risk factors for severe disease 4

Intravenous acyclovir is indicated for:

• Pregnant women with complicated varicella at any stage of pregnancy 4
• Newborns presenting unwell with chickenpox 4
• Adults with severe chickenpox 5

Special Populations and Situations

Breastfeeding and Isolation

• Breastfeeding is encouraged for babies infected with or exposed to VZV 4
• Mothers with chickenpox or zoster do not need isolation from their own baby 4
• Newborns do not require isolation from siblings with chickenpox if given VariZIG 4

Healthcare Settings

• Healthcare personnel must be vaccinated due to severe disease risk in immunocompromised patients and high transmission risk 1
• Substantial exposure in hospitals includes sharing a room or direct face-to-face contact with infectious patients 1

School and Institutional Requirements

• All students entering school, college, and postsecondary institutions should have received 2 doses or have other evidence of immunity 1
• School-entry requirements should be enforced at all grade levels including college 1

Common Pitfalls

• Do not delay VariZIG beyond 10 days - while earlier is better, administration up to 10 days post-exposure shows comparable efficacy to earlier administration 1, 2
• Do not assume bone marrow transplant recipients are immune - they should be considered non-immune regardless of prior history 1
• Do not use MMRV vaccine for persons ≥13 years - only single-antigen varicella vaccine is licensed for this age group 1
• Do not forget extended monitoring - patients receiving VariZIG require 28-day observation period, not the standard 21 days 1