Comparison of Vaccine Adverse Events Between Zoster Vaccine Live and Recombinant Zoster Vaccine: A Prospective...

The burden of herpes zoster has been mitigated through the introduction of two types of vaccines, including zoster vaccine live (ZVL) and recombinant zoster vaccine (RZV). We aimed to compare the occurrence of adverse events within 90 days of vaccination.

We prospectively enrolled participants who received ZVL or RZV between October 2022 and November 2024 at five tertiary hospitals and nine primary care clinics in South Korea. Data on solicited and unsolicited adverse events were collected using questionnaires at 1, 3, 7, 28, and 90 days after vaccination. Demographic and clinical data including vaccination history, previous episodes of herpes zoster, underlying diseases, and immune status were also collected. Multivariable logistic regression analysis was conducted to assess the risk of solicited adverse events according to clinical variables.

In total, 1,527 participants were enrolled, with 487 receiving ZVL, 632 receiving the first RZV dose, and 408 receiving the second RZV dose. In multivariable logistic regression analysis after adjusting clinical variables, the adjusted odds ratios (ORs) for the risk of solicited adverse events at day 1 were significantly lower in 11 categories for the ZVL group compared to the first-dose RZV group. However, for the second-dose RZV group, the adjusted ORs were significantly higher in 9 categories when compared to the first-dose RZV group. No life-threatening vaccine-related events occurred in the unsolicited adverse event reports between days 8 and 90.

After adjusting for clinical variables, the risks of many solicited adverse events were highest in the second-dose RZV group, followed by the first-dose RZV group, and were lowest in the ZVL group. However, the differences in risk diminished from day 1 to day 7. No fatal events occurred in either group. Clinicians should be aware of early reactogenicity of RZV.