What Does It Mean When a Vaccine Trial Is Double-blinded?

In this short video, Dr. Stanley Plotkin explains what a double-blinded clinical trial entails and why this type of trial is important.

Transcript

What Does It Mean When a Vaccine Trial Is Double-blinded?

I am Stanley Plotkin, Professor Emeritus of Pediatrics at the University of Pennsylvania.

When vaccines — or for that matter drugs — are tested, it is important that the observers not be influenced by knowing who received vaccine and who received a controlled substance. So, all trials of vaccines start with what they’re called double-blinded trials, which means that the observers do not know during the trial who received the vaccine and who received a harmless control substance. So at the end of the day when the code is broken, one can compare the two groups knowing that the observers were not influenced in any way by knowing who received the vaccine and who did not.

Related Centers and Programs: Vaccine Education Center

Last Reviewed on Jan 10, 2020