Person receiving vaccine.

Why Do Differences in Clinical Trial Design Make It Hard to Compare COVID-19 Vaccines?

Cross-posted from Written Description, where it originally appeared on June 30, 2021. 

By Lisa Larrimore OuelletteNicholson PriceRachel Sachs, and Jacob S. Sherkow

The number of COVID-19 vaccines is growing, with 18 vaccines in use around the world and many others in development. The global vaccination campaign is slowly progressing, with over 3 billion doses administered, although the percentage of doses administered in low-income countries remains at only 0.3%. But because of differences in how they were tested in clinical trials, making apples-to-apples comparisons is difficult — even just for the 3 vaccines authorized by the FDA for use in the United States. In this post, we explore the open questions that remain because of these differences in clinical trial design, the FDA’s authority to help standardize clinical trials, and what lessons can be learned for vaccine clinical trials going forward.

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