Billionaire philanthropist Bill Gates says that President Trump asked him in two different meetings if HPV and HIV are the same thing. "Both times he wanted to know the difference between HIV and HPV and so I was able to explain that those are things that are rarely confused with each other," Gates recalled during an address to staffers at the Gates Foundation recently.

Video of Gates' remarks was obtained by MSNBC. Gates said he had gone to see Mr. Trump for the first time in December 2016, after he had been elected.

Human papillomavirus, known as HPV, is the most common sexually transmitted infection in the U.S. There are many different types of HPV, according to the Centers for Disease Control, and some of them cause genital warts and cancers. There are vaccines that have been developed for HPV.

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HIV is human immunodeficiency virus. It spreads through some body fluids via blood transfusions and unprotected sex. It can be transmitted from mother to baby during pregnancy, birth, and breastfeeding. If untreated, it develops into AIDS. HIV never leaves the human body, but it can be treated effectively with antiretroviral therapy.

Gates also told the audience that Mr. Trump asked him "if vaccines weren't a bad thing because he was considering a commission to look into ill effects of vaccines." Robert Kennedy Jr., he went on to say, "was advising him that vaccines were causing bad things and I said, 'No, that is a dead end, that would be a bad thing, do not do that.'"

When Gates met with Mr. Trump, he was surprised to hear him speak about himself in the third person: "When I walked in his first sentence kind of threw me off. He said, 'Trump hears that you don't like what Trump is doing.' And I thought, 'Wow, but you're Trump.' So...I didn't know if the third-party form was what was expected."

The Microsoft co-founder also said that Mr. Trump knew his equestrian daughter, Jennifer Gates, because "Trump has this horse show thing down in Florida." He may have been referring to an annual show jumping event the president holds at his Palm Beach resort, Mar-a-Lago. Gates said that Mr. Trump "talked to Jen and was being super nice. And then around 20 minutes later he flew in on a helicopter to the same place. So clearly he had been driven away and he wanted to make a grand entrance on a helicopter."

Gates also said that "when I first talked to him it was actually kind of scary how much he knew about my daughter's appearance. Melinda [Gates] did not like that too well."

The president and Gates also met in March last year to talk about strides in global health and development, as well as education.