After an openly gay San Francisco supervisor announced last week that he's taking Truvada to reduce the risk of contracting HIV, a second official said he'll introduce a measure to subsidize the cost of the drug.

Supervisor Scott Wiener on Wednesday disclosed that he's participating in the treatment known as pre-exposure prophylaxis, or PrEP.

The following day, Supervisor David Campos announced he's backing a plan to make PrEP cheap or free for residents who can't afford the treatment.

“This coming Tuesday, I will introduce a measure to allocate funds for navigators to educate patients about PrEP, and provide subsidies to San Franciscans who cannot afford the life saving medication,” he said in a Facebook post.

“By making PrEP available to all regardless of income, we could set the tone for the rest of country in how to effectively eradicate a disease that claimed the lives of so many of our loved ones,” he added.

The daily regimen was approved by the Food and Drug Administration in 2012 and some researchers believe it may reduce the risk of infection by 99 percent, when taken as prescribed.

Critics, however, argue that it's too early to embrace Truvada, noting its possible toxic side effects and high price tag of over $1,000 a month for the uninsured. Others worry that PrEP will encourage risky sexual behavior.

At a rally Thursday, Wiener said he's in favor of widespread adoption of the regimen.

“Ending this epidemic can't just be limited to people who happen to have good insurance,” he said. “We have to expand access. We have to make sure that people who either don't have insurance or have insurance with really high deductibles or high co-pays have access.”