Facebook said during its earnings call last week that mobile users contribute 80% of its revenue. In just four years, the social networking giant’s mobile business stands at $13 billion, while the picture is the opposite for veteran internet firm Yahoo.

Yahoo! Inc. Bigger In Age, Facebook Inc In Revenue

Yahoo vs. Facebook

On Tuesday, Yahoo announced its fourth quarter earnings, saying it made $1.3 billion in revenue for the quarter but just 23% ($291 million) came from mobile. Yahoo CEO Marissa Mayer has said in the past that it is the world’s third-largest mobile advertising company and that there are roughly 575 million users who visit its mobile properties.

When compared to other mobile advertising businesses like Facebook, it appears that Yahoo is having trouble in translating that base into revenue. In the last quarter of 2015, Facebook’s mobile advertising contributed revenue of around $4.5 billion or roughly 15 times of what Yahoo made in the same period, says a report from Quartz. Facebook was founded in 2004 — nine years after Yahoo.

Mayer is trying to turn the company around, and mobile is one of the key areas she intends to grow. During the earnings call, she said that the company will double down on its mobile search efforts, even if it trims itself down. Yahoo also announced plans to cut down its workforce by 15%. Mayer said on the call that the company’s size has shrunk 34% in the last five years.

Nevertheless, Yahoo’s mobile business is growing, and mobile revenue went up 15% from the same quarter last year. However, it remains to be seen whether the company succeeds at rebounding as the Internet becomes increasingly mobile.

Facebook launches campaign against Zika virus

In related news, Facebook is launching a public awareness campaign for the Zika virus targeted at women in Brazil and Latin America, CEO Mark Zuckerberg announced yesterday. The Zika virus is a mosquito-spread disease that affects pregnant women and leads to the birth of babies with microcephaly.

The World Health Organization (WHO) has declared an emergency in Brazil where over 4,000 cases of microcephaly have been documented since October. Other countries in Latin America, like El Salvador, are headed for similar designations. On Tuesday, Facebook released the first video in Portuguese with English subtitles detailing the steps a pregnant women should take to avoid mosquitoes. This video has been created in partnership with Brazil’s public health wing.