When it comes to making sure that fake news is not spread, to me the bulk of the responsibility falls on the public.
There is only so much that the social media companies like Facebook and Twitter can do to prevent fake news from spreading. They can make algorithms to hide some stories, but ultimately if someone shares a fake news story it could end up getting shared by thousands of people.
Also, the public is the consumer of news in general and they do share news stories they find interesting. All a journalist does is write the story, but if nobody shares it then fake news cannot be spread. It is up to the public to be a watchdog for the watchdogs in a sense.
The public needs to make sure what they are reading is actually true and they can do that through paying more attention to the article or researching other articles about the topic they are reading about.
Fake news can be compared to a virus in a way. Someone writing an article that contains fake news is just one person having the virus.
However, a virus cannot be spread if nobody comes into contact with it. Just like with a virus, if nobody comes into contact with fake news and sees it as the truth, then the fake news virus cannot be spread.