Protection against Severe Varicella Disease

Safety and Immunogenicity of the Live Attenuated Varicella Vaccine in Vietnamese Children Aged 12 Months to 12 Years: An Open-Label, Single-Arm Bridging Study

OBJECTIVE

This study aims to evaluate the safety and immunogenicity of the SKYVaricella vaccine in healthy Vietnamese children aged 12 months to 12 years.

METHODS

This open-label, single-arm study involved 201 children divided into two groups: 60 children aged 12 months to 5 years and 141 children aged 6 to 12 years. Safety was assessed through immediate reactions, solicited adverse events within 7 days, and unsolicited events up to Day 42. Immunogenicity was evaluated by seroconversion rates (SCR) and geometric mean titer (GMT) increments using fluorescent antibody-to-membrane antigen (FAMA) on the day of vaccination (D0) and 42 days after vaccination (D42).

RESULTS

All participants completed the follow-up. Immediate adverse events included pain (8.0%), redness (8.0%), and swelling (20.9%) at the injection site. Within 7 days, pain (17.9%) and swelling (12.4%) were mild and self-resolving. Unsolicited adverse events were infrequent and mild. Both age groups achieved 100% SCR. GMT of varicella-zoster virus antibodies increased from 1.37 (SD 1.97) at D0 to 18.02 (SD 2.22) at D42, a 13.12-fold rise. No Grade 3 adverse events were observed.

CONCLUSION

The SKYVaricella vaccine shows a robust immunogenic response and favorable safety profile in Vietnamese children aged 12 months to 12 years. These findings endorse its potential inclusion in pediatric vaccination programs as a reliable preventive option against varicella.

Severe varicella in a child immunosuppressed with methotrexate

Varicella is a common viral infection in childhood and usually has a benign evolution. However, the evolution can be severe in immunosuppressed children. Vaccination can prevent its occurrence and especially the development of severe and/or complicated cases. Methotrexate is a systemic therapeutic option for many inflammatory diseases, and its immunosuppressive action exposes its users to a higher susceptibility to infection. The present report describes a case of severe varicella infection in a child immunosuppressed with methotrexate.