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According to guidance from the World Health Organization (WHO), the use of the Barycela vaccine in either one-dose or two-dose immunization schedules for children is considered appropriate.
The use of the Barycela vaccine in one- or two-dose schedules for children is fully appropriate. Photo: NAVIVA GROUP
In the latest WHO guidelines on varicella vaccination, published in November 2025, a two-dose vaccination schedule is recommended to achieve optimal protection against varicella.
Results from studies cited as evidence for this recommendation demonstrate a significant increase in effectiveness with a two-dose schedule compared to a single-dose regimen.
With only one dose, varicella vaccine effectiveness reaches approximately 95% [1]. In contrast, with a two-dose schedule, vaccine effectiveness increases to 100% [2].
In this document, WHO also emphasizes that countries currently implementing a one-dose varicella vaccination schedule should note that such programs are primarily sufficient to reduce mortality and severe disease, rather than to fully prevent virus circulation and outbreaks.
A one-dose schedule is therefore less effective in preventing viral transmission and varicella outbreaks. The second dose should be administered at an interval of at least four weeks after the first dose. Older children and adults should also receive this booster dose to achieve optimal immunity.
The updated WHO guidance further confirms that the safety and immunogenicity of the MAV/06 strain varicella vaccine—commercially known as Barycela—are comparable to those of Oka strain varicella vaccines commonly used in current commercial products [3,4].
Long-term use of the Barycela vaccine in the National Immunization Program of South Korea, as well as in several other countries, has demonstrated a marked reduction in varicella incidence, including a decrease in cases of herpes zoster (shingles) among vaccinated children [5].
WHO publications also clearly state that interchanging live attenuated varicella vaccines between the Oka strain and the MAV/06 strain is safe, with no adverse reactions observed in healthy vaccinated children [6].
Barycela varicella vaccine manufactured by GC Biopharma (South Korea). Photo: NAVIVA GROUP
Based on the above recommendations, the use of the MAV/06 strain varicella vaccine (Barycela) in either one-dose or two-dose schedules for children is considered fully appropriate.
The Barycela varicella vaccine contains the MAV/06 strain, is manufactured by GC Biopharma (South Korea), and is currently distributed in Vietnam by NAVIVA GROUP.
- Bayer O et al. Metaanalysis of vaccine effectiveness in varicella outbreaks. Vaccine. 2007;25(37–38):6655–60.
- Hong K et al. Effectiveness of two-dose varicella vaccination: Bayesian network meta-analysis. Pediatr Infect Vaccine. 2024;31(1):55–63.
- Kim SH et al. Seroprevalence rate after 1 dose of varicella vaccine in infants. J Infect. 2010;61(1):66–72.
- Choi UY et al. Immunogenicity and safety profiles of a new MAV/06 strain varicella vaccine in healthy children: a multinational, multicenter, randomized, double blinded, active-controlled phase III study. Vaccine. 2021;39(12):1758–64
- Choi J-K et al. Trends in varicella and herpes zoster epidemiology before and after the implementation of universal one-dose varicella vaccination over one decade in South Korea, 2003–2015. Hum Vaccin Immunother. 2019;15(11):2554–60.
- Kang HM et al. Safety of interchanging the live attenuated MAV/06 strain and OKA strain varicella vaccines in children. Vaccines (Basel). 2023;11(9):1442.
The updated WHO varicella vaccine guidance clearly states:
– A two-dose varicella vaccination schedule, with doses administered at least four weeks apart, is necessary to achieve optimal protective effectiveness.
– The MAV/06 strain varicella vaccine (Barycela) demonstrates safety and immunogenicity equivalent to Oka strain varicella vaccines commonly used in current commercial formulations.
– Interchangeability between live attenuated Oka and MAV/06 varicella vaccines is safe, with no adverse reactions reported in healthy vaccinated children.
Source: Lao Dong Newspaper
