Human rights groups on Monday praised the official lifting of a decades-old ban that prevented people with HIV/AIDS from travelling to the United States.
President Barack Obama announced in October that his administration would end the ban, and the legislation lifting the travel restrictions came into effect on Monday.
"We're very excited to finally see the end of this discriminatory and harmful policy," said Victoria Neilson, legal director at the advocacy group Immigration Equality.
"Getting rid of the HIV ban has been part of our core mission since we were founded in 1994," she told AFP.
The ban on HIV-positive foreigners entering the United States had been in place since 1987.
While people living with the virus could receive 30-day waivers to visit the United States, the ban made it nearly impossible for HIV-positive individuals to study or work at US institutions.
The Human Rights Campaign, which advocates for gay, lesbian, bisexual and transgender rights, also hailed the end of the ban.
"Today, a sad chapter in our nation's response to people with HIV and AIDS has finally come to a close and we are a better nation for it," said HRC President Joe Solmonese.
"This policy, in place for more than two decades, was unnecessary, ineffective and lacked any public health justification," he added in a statement.
Ending the travel ban had been an uphill struggle for rights groups, who saw former president Bill Clinton's attempts to repeal the restrictions shot down by conservatives.
But ultimately it was former president George W. Bush, a staunch Republican, who set in motion the end of the ban by removing HIV from a list of diseases "of public health significance."
It then fell to the Obama administration to issue a rule ending the travel restrictions, which was announced in October as the president signed a bill extending funding for HIV/AIDS treatment.
Neilson said lifting the ban proved much less controversial this time around.
"I think it's a sign of changing attitudes across the board," she said. "It just seemed like more of a non-issue at this point.
"Fifteen years later there's just so much more information about how HIV is and is not transmitted... at this point it's seen much more as a virus, as it should be, than as a plague."
Among the first travellers taking advantage of ban's lifting are Clemens Ruland and Hugo Bausch, who are to arrive at New York's JFK airport from the Netherlands later Monday, according to Immigration Equality.
The end of the ban was also heralded by the International Aids Society, which announced in November it would hold its 2012 conference in the US capital, Washington, where three percent of all residents over the age of 12 have HIV or AIDS.
The United Nations' HIV/AIDS agency and the US Centers for Disease Control and Prevention (CDC) have said HIV is "generalized and severe" when one percent of a given population is infected.
Some 1.1 million people in the United States are believed to have HIV, according to the CDC.