Welcome back to Know Your Data Season 2. This week we’re looking at the use of the data around vaccines, covering two terms that are often confused – effectiveness and efficacy.

You can’t read the news today without seeing the word effectiveness when it comes to vaccines. It might sound correct, but it’s actually the wrong word to use when referring to COVID-19 vaccine development. Right now, we can only report on the data behind the efficacy of the vaccine and not its effectiveness.

Why? Because efficacy data talks to how well a vaccine works in a controlled clinical trial, which is what has been done so far. Effectiveness is how well a vaccine works in the real world over time. This is something we don’t know yet as it hasn’t been rolled out to enough people.

It’s hugely important that we all understand the terms being used – and when they are being used incorrectly. So, tune in to the latest episode now to hear from myself and former New York Times journalist Alan Schwarz as we unpack the correct uses of ‘effective’ and ‘efficacy’ as it relates to the COVID-19 vaccine.

As a reminder, if you want to discuss this more, or want us to cover something you’ve seen out there in the media or online, you can reach us on Facebook, Twitter, YouTube or Instagram. Make sure to include the hashtag #BeDataBrilliant in your social post. You can also email us at [email protected].