PSI Vaccine SIG Webinar: Evaluating the Durability of Protection for COVID-19 Vaccines
Date: Thursday 28th October 2021
Time: 16:00-17:00 BST
Speaker: Prof. Dan-Yu Lin (Department of Biostatistics, University of North Carolina at Chapel Hill)
Who is this event intended for? Statisticians working on Vaccines or related topics to COVID-19.
What is the benefit of attending? To learn how to evaluate the duration of protection of COVID -19 vaccines and about the performance of blinded and unblinded crossover designs in estimating long-term vaccine efficacy.
Large-scale deployment of safe and durably effective vaccines can curtail the COVID-19 pandemic. The COVID-19 vaccines currently in use were approved on the basis of efficacy and safety data from phase 3 trials with a median follow-up time of only about two months. Because of crossover, the phase 3 trials provided little information about the efficacy of these vaccines beyond 6 months. Typically, estimates of vaccine efficacy over broad time intervals are reported, which are not informative about the level of waning at the end of the observation period. Observational studies can potentially provide information about long-term vaccine effectiveness, but they are more difficult to be analysed. In this talk, I will discuss how to properly measure and estimate vaccine efficacy/effectiveness as a function of time elapsed since vaccination while properly accounting for changing transmission rates over calendar time. I will present results on the long-term effectiveness of the Pfizer, Moderna, and Janssen vaccines against Covid-19, hospitalisation, and death in the United States.
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Prof. Dan-Yu Lin
Large-scale deployment of safe and durably effective vaccines can curtail the COVID-19 pandemic. However, the high vaccine efficacy reported by ongoing phase 3 placebo-controlled clinical trials is based on a median follow-up time of only about two months and thus does not pertain to long-term efficacy. To evaluate the duration of protection while allowing trial participants timely access to efficacious vaccine, investigators can sequentially cross participants over from the placebo arm to the vaccine arm. Here, we show how to estimate potentially time-varying placebo-controlled vaccine efficacy in this type of staggered vaccination of participants. In addition, we compare the performance of blinded and unblinded crossover designs in estimating long-term vaccine efficacy.