A group of Havas agencies developed a song and a ritual for a Reckitt Benckiser campaign encouraging people to use mosquito repellant and get rid of standing water as part of an effort to eradicate the Zika virus.

The campaign was a success by marketing standards — a video of Ivete Sangalo, a popular performer in the region, singing a song and dancing a ritual developed for the campaign, generated 9 million views. It was also a success within the agency, for a different reason.

“Millennials worked twice as hard because there was a purpose behind it,” said Toygar Bazarkaya, ‎chief creative officer of the Americas at Havas Worldwide.

Havas Worldwide Brazil developed Palmas Pelo Brasil, which means Clap for Brazil, for its client, Reckitt Benckiser, which makes several repellent products. It’s based on the idea that you clap to kill a mosquito.

“It energized the employees, the brand, and the agencies,” Bazarkaya said during a talk held Tuesday at the Cannes Lions International Festival of Creativity.

See also: Brazilian agencies create billboard that kills Zika-carrying mosquitoes

As the millennial workforce grows and take on more senior roles at their respective employers, agencies and companies have started to see that the purpose-driven generation wants to know that some or all of the work they do has a social-good element to it. That’s why media brands like Mashable take a “positive, aspirational, and inclusive” tone, said Michael Kriak, Mashable’s chief operating and financial officer.

It’s also a driver for global communications firms like Weber Shandwick. “Our business is full of millennials,” said Jack Leslie, chairman of Weber Shandwick.

Doing work with a purpose helps employers both attract and retain millennial talent. Leslie noted a recent Deloitte study that found 88% of millennials say they will stay at an organization for five years or more if there is a sense of purpose. That quality was more important to the participants than professional development, aligned values, and mentoring programs.