A model developed with long-term clinical trial data on breakthrough infections caused by varicella-zoster virus (VZW) showed that the single-dose Varivax® (V-MSD) vaccine conferred more durable protection compared with the 2-dose Varilrix® (V-GSK) vaccine. However, protection conferred by 2 doses of each vaccine was similar. These findings were published in Vaccine.
Researchers used data captured from simulated clinical trials to develop a novel model that assessed the protective effects of the V-MSD and V-GSK vaccines against VZW infection. They used deterministic compartmental models to estimate the “take,” defined as the number of individuals for which a vaccine confers protection, and the duration of protection for both vaccines.
The researchers found that the rate of permanent protection conferred by a single dose of the V-MSD vaccine was increased vs a single dose of the V-MSD vaccine (90.3% vs 61.7%). Estimates of the rate of permanent protection conferred by 2-doses of V-MSD and V-GSK vaccines were found to be similar, with rates of 97.0% (95% CI, 95.2-98.8) and 93.8% (95% CI, 92.2-95.4), respectively.
Further analysis was performed to estimate duration of temporary protection following a single dose of each vaccine. Results showed that the V-MSD and V-GSK vaccines conferred 1.21 (95% CI, 0.77-2.85) and 0.88 (95% CI, 0.69-1.20) years of protection against VZW infection, respectively.
Limitations included that clinical trial data used to model the effects of each vaccine were inconsistent in regard to patient populations, study designs, and follow-up periods. In addition, the researchers did not adjust for differences in baseline characteristics of the patients from whom the clinical trial data used for the model were captured.
According to the researchers, “[these findings] provide robust estimates of vaccine performance which can be used in future modeling studies to accurately assess the long-term health impact and cost-effectiveness of different varicella vaccination strategies.”
Disclosure: This research was supported by Merck Sharp & Dohme Corp., and some authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Pillsbury M, Carias C, Samant S, Greenberg D, Pawaskar M. Comparison of performance of varicella vaccines via infectious disease modeling. Vaccine. 2022;40(29):3954-3962. doi:10.1016/j.vaccine.2022.05.003