Persistence of Protection by Shingrix

The study plans to learn more about how the shingles vaccine, Shingrix (SRX), successfully prevents shingles in older people. Two vaccines are currently approved by the Food and Drug Administration (FDA) to prevent shingles. Zostavax is a live virus vaccine which has been available since 2006 and prevents shingles about 50% of the time, though it is less effective the older a person is when they receive it. Shingrix, which was approved by the FDA in 2017, is not a live virus, but has an additive in the vaccine to boost immune response. It is about 97% effective at preventing shingles regardless of a person's age and so far has been effective for at least 4 years after vaccination. Because Zostavax has live virus in it, giving a "challenge" dose of Zostavax - vOka varicella zoster virus - to people who have received both vaccines (Zostavax or Shingrix) in the past, will allow researchers to learn more about how the body works to prevent shingles and how any shingles vaccination helps protect against shingles.

The primary endpoint of this study was the area under the concentration/time curve of quantitative VZV DNA in plasma. However, all the VZV DNA measurements were below the lower limit of quantitation of the assay. Due to this unexpected outcome, we performed a qualitative analysis of presence or absence of VZV DNA in plasma at Day ≥3 after the vOka challenge.