More than three decades after the AIDS pandemic swept into New York and the nation to claim hundreds of thousands of lives, an amazing moment has arrived.

For the first time a pill is available that can prevent transmission of HIV -- the virus that causes AIDS -- during sex.

Its name is Truvada -- and it is a key ingredient in the daily cocktail that has prolonged the lives of many who have already contracted the virus.

But here's the startling news: When those who aren't infected take the pill once a day, Truvada is more than 90 percent effective in blocking HIV transmission. The U.S. Centers for Disease Control and Prevention has issued guidelines for using the pill to prevent the spread of HIV.

Seizing the moment, Gov. Andrew M. Cuomo recently announced a strategy -- built around Truvada -- to reduce new HIV infections statewide from 3,000 a year to 750 by 2020. It's an ambitious, trailblazing idea -- and reaching the target will take an unflagging, collaborative effort.

But if it can be accomplished, officials say, the number of New Yorkers living with HIV would be reduced for the first time since the first cases were diagnosed in 1981.

We cannot afford to miss this goal.

Great strides have already been made. In New York and the nation, HIV transmission via blood transfusions and from mother to child have been virtually eliminated. New infections from IV drug use have been dramatically reduced. And with the arrival of antiretroviral drugs in treating HIV, the infection is no longer a death sentence.

But there's still no cure or vaccine. And the CDC estimates that nationally there are still 50,000 new infections a year.

Yet New York -- an epicenter of the crisis for decades -- now has a shot to become the first state to reduce AIDS to less than an epidemic by driving the total of new infections below the total of HIV-related deaths.

While Truvada is the core of the state's strategy, other factors have also helped fuel optimism among public health officials.

Since 2010, New York's doctors have been required to offer HIV testing to all patients ages 13 to 64. Since April, written authorization for testing is no longer required. Doctors and public health officials may now share information to find patients who drop out of treatment. And the Affordable Care Act requires insurers to cover HIV screening with no out-of-pocket costs.

The state's plan includes strategies to identify the estimated 22,000 New Yorkers who are HIV positive but don't know it. And it aims to ensure that the 64,000 who know they're HIV positive -- but aren't in treatment -- get anti-HIV therapy.

For HIV-negative adults at high risk -- say, men and women with HIV-positive partners -- the plan will provide access to Truvada, officially known as pre-exposure prophylaxis, or PrEP.

The state has committed $5 million to the plan this year. The goal: educating doctors about the preventive therapy and pushing them to consistently offer testing.

Advocacy groups have been enlisted to engage at-risk people in conversation at bars and clubs and other venues. Their mission is to spread the word about prevention inroads and address unfounded worries about the minimal side effects.

Medicaid and most private insurance plans cover Truvada's $1,300-a-month cost. And Gilead Sciences Inc., the California- based company that makes the drug, has a program to defray costs, if needed.

The state's bill for HIV medication will likely grow before savings from averted infections is realized. Meanwhile, there's a worry PrEP might hasten a return to unsafe sex, though Gilead and CDC warn that PrEP isn't meant to replace other prevention tools like condoms. But if done right, the plan could end the HIV epidemic here -- and make the impossible dream come true.

This editorial has been updated to correct the cost of Truvada. Treatment is $1,300 a month. An incorrect amount appeared in an earlier version of this editorial.