Supervisor David Campos wants the city of San Francisco to set aside more than $800,000 to pay for public education and subsidies for the first drug that can prevent HIV infection. Truvada is an antiviral drug that has been used to treat HIV infection for more than a decade and is the only pill approved for preventing the disease - but it's been weighed down by stigma and controversy over claims it encourages unprotected sex. The city money, if approved by the board and spent by the mayor, would pay for health workers to educate patients about PrEP and provide subsidies to San Franciscans who cannot afford the drug.