A recent Facebook challenge went viral asking users to post a photo of themselves from 10 years ago next to one from today. Over 5.2 million people, including many celebrities, participated in the challenge. But the challenge has caused quite a stir and some concern from users. June-wei Sum has more.

It's called the 10-Year Challenge a social media trend that calls on people to post photos of themselves - mostly from 10 years ago and now.

The challenge has gone viral. It generated an estimated five million Facebook interactions in just its first three days. There were posts from celebrities like Jennifer Lopez, Reese Witherspoon and a tongue in cheek entry from singer Mariah Carey, who used the same photo side-by-side.

It's also gone from photos of people to things - some showing positive change to the world around us - others not so much. But is this an exercise by big tech to harvest data?

A journalist from Wired magazine sent out a semi-sarcastic tweet, pondering "how all this data could be mined to train facial recognition algorithms on age progression and age recognition." Kate O'Neill's tweet started gaining traction, and soon many social media users were starting to second-guess the intent behind the challenge.

Facebook itself said, "This is a user-generated meme that went viral on its own. Facebook did not start this trend."

SHERYL SANDBERG CHIEF OPERATING OFFICER, FACEBOOK "We're investing billions of dollars a year in what is a much more rigorous security effort, and we know we need to earn back trust and that means we need to prove it. So from everything from election integrity to fake news on our platform to getting the right content up to protecting people's data and information, we're taking a much more rigorous approach."

But after recent data privacy breaches, consumer trust in Facebook has eroded. Some might wonder if even billions of dollars, while not too little, may be too late. June-wei Sum, CGTN.