Skipping Phase 3 of clinical trials and rushing out a COVID-19 vaccine is a *terrible* idea. It goes against medical ethics, puts people at greater risk and undermines trust in the vaccine approval system. It causes more problems than it tries to solve. Let me explain. 1/10

Today @StevenSalzberg1 claimed Phase 3 was “excessive caution” and advocated for administering millions of doses now. @DrEricDing falsely suggested the bioethics warrants giving it to volunteers before Phase 3 is complete. 2/10
https://twitter.com/DrEricDing/status/1289892233613778947?s=20

Sample sizes for Phase 1 and 2 of clinical trials don’t have the statistical power to detect all side-effects or determine effectiveness in the general population. They are designed to test for safety and effectiveness with samples of several hundred people. 3/10

If the vaccine performs well in Phase 2, then it’s deemed to be safe enough for a Phase 3 trial with a larger sample size and longer time frame. But there are risks inherent in a Phase 3 trial! 4/10

From the @US_FDA website:
“Phase 3 studies provide most of the safety data... Because these studies are larger and longer in duration, the results are more likely to show long-term or rare side effects” 5/10 https://www.fda.gov/patients/drug-development-process/step-3-clinical-research

The ethics of clinical trials ensure that *the benefits outweigh the risks*. The risks are minimized by close monitoring by the study team. The trial will shut down if there are indications of serious side-effects. 6/10

From @NIH: “Has everything been done to minimize the risks and inconvenience to research subjects, to maximize the potential benefits, and to determine that the potential benefits to individuals and society are proportionate to or outweigh the risks?” 7/10 https://clinicalcenter.nih.gov/recruit/ethics.html#4

The main benefit of the Phase 3 trial is that we get valuable data that tells us whether the vaccine is effective or not. Rushing doses to volunteers outside of a trial has much more risk and none of the benefits of Phase 3. Medical ethics stands firmly against this. 8/10

If you look at the hundreds of COVID-19 patients dying each day, you may think that the solution is to skip Phase 3 of vaccine clinical trials. But that is extremely short sighted. 9/10

Our way out of the pandemic involves the public having enough trust in the vaccine program that the vast majority is willing to take an approved vaccine. It’s clearly worth waiting to a little longer to complete Phase 3 to ensure that this trust is preserved. 10/10 #medtwitter

My thread in a nutshell: https://twitter.com/zoemclaren/status/1250961885236772864