Varicella Vaccine Effectiveness and Duration of Protection: A Systematic Review and Meta-Analysis.

BACKGROUND

This study provides a comprehensive review of studies comparing the effectiveness of varicella vaccinations and the duration of their protection.

METHODS

We conducted a systematic literature review to identify comparative studies evaluating the effectiveness of the varicella vaccine. A meta-analysis was performed to assess the effectiveness of one-dose and two-dose vaccinations, as well as the outcomes for moderate and severe illness, and the duration of protection, using random effects models.

RESULTS

Out of 66 studies, 57 reported the effectiveness of a single-dose varicella vaccine, 28 examined the two-dose vaccination, and 25 focused on effectiveness against moderate to severe disease. Of these, 59 were observational studies and 7 were trials. Thirteen studies reported the duration of protection. The overall vaccine effectiveness for a single dose was 79% (76-82%; I² = 97.2%), while for two doses, it was 94% (93-96%; I² = 90.8%). The overall effectiveness against moderate or severe illness was 92% (90-94%; I² = 90.3%). The duration of protection showed a slight decline over time. Evidence suggests that both one and two doses of the varicella vaccine offer short-term protection, though this protection wanes rapidly.

CONCLUSION

The two-dose vaccination demonstrated superior clinical efficacy compared to the one-dose vaccination, with protection slightly diminishing over time. These findings highlight the importance of implementing universal two-dose varicella vaccination programs in countries.

TRIAL REGISTRATION: PROSPERO Identifier: CRD42024589864.