Is the varicella (chickenpox) vaccine recommended for individuals who have never been exposed to varicella (chickenpox)?

From the Guidelines

The varicella vaccine is recommended for individuals who have never been exposed to varicella, as it provides effective prevention against the disease and its complications. According to the Advisory Committee on Immunization Practices (ACIP) recommendations [ 1 ], all healthy adults should be assessed for varicella immunity, and those who do not have evidence of immunity should receive 2 doses of single-antigen varicella vaccine 4-8 weeks apart. This recommendation is based on the fact that varicella vaccine is an effective prevention tool for decreasing the burden attributable to varicella disease and its complications [ 1 ].

Key Points to Consider

• The varicella vaccine is approximately 85% effective in preventing varicella and >95% effective in preventing severe varicella disease [ 1 ].
• Breakthrough varicella disease that occurs after vaccination frequently is mild and modified [ 1 ].
• Second dose catch-up varicella vaccination is recommended for children, adolescents, and adults who previously received 1 dose, with a minimum interval of 3 months for children aged <12 years and 4 weeks for persons aged >13 years [ 1 ].
• The vaccine is recommended for individuals who might be at increased risk for exposure or transmission, including healthcare professionals, household contacts of immunocompromised persons, and persons who live or work in environments in which transmission of VZV is likely [ 1 ].

Recommendation

Individuals who have never been exposed to varicella should receive 2 doses of single-antigen varicella vaccine 4-8 weeks apart, as recommended by the ACIP [ 1 ]. This recommendation prioritizes the prevention of varicella disease and its complications, and is based on the strongest and most recent evidence available [ 1 ].

From the FDA Drug Label

What is VARIVAX and how does it work? VARIVAX is also known as Varicella Virus Vaccine Live. It is a live virus vaccine that is given as a shot. It is meant to help prevent chickenpox. Chickenpox is sometimes called varicella (pronounced VAR ih sell a). VARIVAX contains a weakened form of chickenpox virus. VARIVAX works by helping the immune system protect you or your child from getting chickenpox

The varicella (chickenpox) vaccine is recommended for individuals who have never been exposed to varicella (chickenpox), as it helps prevent chickenpox by protecting the immune system against the virus.

• The vaccine is given as a shot to people who are 12 months old or older.
• A second dose should be given to those who first get the vaccine when they are 13 years old or older.
• The vaccine may not protect everyone who gets it, but it has been shown to be effective in preventing chickenpox in a significant portion of the population 2.
• Clinical trials have demonstrated the efficacy of the vaccine in preventing varicella, with estimated vaccine efficacy for the 10-year observation period being 94% for 1 dose and 98% for 2 doses 2.

From the Research

Varicella Vaccine Recommendation

The varicella vaccine is recommended for individuals who have never been exposed to varicella (chickenpox) due to the following reasons:

• High infectivity and potential for severe complications, such as secondary bacterial skin infection, pneumonia, and encephalitis 3
• Effectiveness of the vaccine in preventing and attenuating the disease, with a preventive effect of approximately 80% for all types of varicella and 95% or greater for moderate to severe disease 3
• Recommendation for vaccination in specific groups, such as adolescents with a negative varicella history and individuals at increased risk for varicella complications, including adults, pregnant women, premature babies, and immunocompromised persons 4

Post-Exposure Prophylaxis

Post-exposure varicella vaccination may prevent infection or mitigate disease severity in persons eligible for vaccination, and is effective in preventing chickenpox and attenuating the illness when administered within the first 5 days after exposure 5, 6

• The effectiveness of the varicella vaccine in preventing any type of disease was 62.3% and 79.4% in preventing moderate and severe disease 6
• Post-exposure prophylaxis with varicella zoster immune globulin is indicated for populations ineligible for vaccination, including immunocompromised children and adults, pregnant women, newborns of mothers with varicella shortly before or after delivery, and premature infants 5

Vaccination Scenarios

Simulations of different chickenpox and shingles vaccination scenarios suggest that an introduction of the chickenpox vaccine would reduce chickenpox incidence, but may increase shingles incidence under certain conditions 7

• A trade-off between chickenpox and shingles vaccination coverage was discovered, where mid-level chickenpox coverage levels were identified as the optimal target to minimize total zoster burden 7
• Strategies focused on reducing both chickenpox and shingles incidence, but prioritizing the latter, should maximize efforts towards shingles vaccination, while slowly incorporating chickenpox vaccination 7