I Was Wrong: We Can’t Skip Phase 3 Vaccine Trials

I wrote a blog post over the weekend that has generated tremendous pushback, including an op-ed in the New York Times as well as thousands of comments on Twitter.

I was wrong. After reading many of the responses to my article, some of them outlining the risks in greater detail, I have concluded that (1) the risks are greater than I presented them, and (2) the benefits are not as great as I had thought.

On point (1), there are several risks that I didn’t emphasize sufficient. One is that although phase 1 and 2 trials establish safety, they don’t tell the whole story. Phase 3 also looks at safety, and because many more subjects are involved, Phase 3 can identify less-common side effects that might still be very bad. (One example is ADE, which can make a viral illness worse than it would otherwise be.) These less-common side effects are a big risk of moving too quickly.