Speaking at the at the Wall Street Journal’s CEO Summit Wednesday, Gates asked of Elon Musk: “How does he feel about something [on Twitter] that says ‘vaccines kill people’ or that ‘Bill Gates is tracking people?'”Jeff J Mitchell | Getty Images News | Getty ImagesBill Gates has warned that Elon Musk could make Twitter “worse” after the Tesla CEO pledged to buy the social media firm for $44 billion.Speaking at the Wall Street Journal’s CEO Summit Wednesday, Gates said it’s unclear how Musk will change Twitter if he takes ownership while also raising concerns about the spread of misinformation on social media platforms.The Microsoft co-founder admitted that Musk’s track record at other companies is impressive, hailing his time at the helm of Tesla and SpaceX as “mind-blowing.” Gates said he believed Musk had done a good job of putting together a great team of engineers at those companies.”I kind of doubt that will happen this time, but we should have an open mind and never underestimate Elon,” he said.The tech billionaire’s comments come after Musk accused him of shorting Tesla stock last month. Musk also tweeted a crude joke about Gates that CNBC has decided not to print. Gates said the insults don’t bother him.Gates, who has been replaced by Musk as the world’s richest person in recent years, went on to question what Musk’s goal is with Twitter and whether his drive to promote free speech is sensible.”How does he feel about something [on Twitter] that says ‘vaccines kill people’ or that ‘Bill Gates is tracking people?'” Gates asked.”What are his goals for what it ends up being? Does that match this idea of less extreme falsehoods spreading so quickly [and] weird conspiracy theories? Does he share that goal or not?” Gates said.A representative for Musk did not immediately respond to CNBC’s request for comment.Over the last few weeks, Musk has hinted at a number ways he may look to improve Twitter beyond promoting free speech. Late on Tuesday, for example, he suggested that he may start charging companies a “slight” fee to use the platform.Combating misinformationVaccine misinformation has spread like wildfire on social media during the Covid-19 pandemic, with some wrongly claiming that Gates was somehow using vaccines to implant 5G chips into people so that he could track their location.”That’s so unexpected and almost so bizarre,” Gates said. “Now that I’m back in the physical world … people come up and yell and protest.”He said it’s “dangerous” when people “cast out” on the key tool that’s being used to save people’s lives and he believes those who own social media platforms have a role to play when it comes to ensuring the truth gets shared effectively.Musk’s plan to buy Twitter has worried policymakers around the world.Joe Skipper | Reuters”When you don’t have the trusted leaders speaking out about vaccines, it’s pretty hard for the platform to work against that,” he admitted. “So I think we have a leadership problem and we have a platform problem.””The way that you make those platforms spread truth and not crazy stuff, there’s some real invention required there,” Gates said.”It’s a huge problem in terms of legitimacy of elections or medical innovations … any sort of collective behavior,” he added.The fact that information on the efficacy of drugs can move quickly and cheaply should be a blessing to mankind, Gates said, before going on to call the hydroxychloroquine saga “insane.””I can’t explain that,” he said. “I don’t think digital is responsible for that obsession with drugs that don’t work.”Gates said he plans to set up a 3,000-person social media unit to help propagate accurate vaccine information in the future. He stressed that “good messages” need to be carried forward by people of trust in the community, such as political and ethnic leaders.