The watershed moment when NBA legend Magic Johnson said he had HIV

This article is part of Yahoo's 'On This Day' series

Thirty years ago today, Magic Johnson announced his retirement from basketball.

The Los Angeles Lakers point guard made the decision after he tested positive for HIV in a pre-season physical.

On 7 November 1991, Earvin “Magic" Johnson, then 32, held a press conference to tell the world he had played his last game in the NBA.

Read more: Magic Johnson on 1991 HIV diagnosis - ‘I just lost it’

As it turned out, Johnson would go on to play in the Olympics for the famous US “Dream Team” the following year, and eventually play for the Lakers again in 1996.

But at the time of his diagnosis, he was not only uncertain about his sporting future, but his time left alive.

HIV (human immunodeficiency virus) attacks the body’s immune system and if untreated can lead to AIDS (acquired immune deficiency syndrome).

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Three decades ago, in the US, AIDS was still a condition primarily associated with white gay men, so Johnson’s announcement was a watershed moment, showing it could affect anyone.

He also proved that testing positive for HIV did not mean that life was over.

In his press conference, Johnson said: “Because of the HIV virus that I have attained, I will have to retire from the Lakers. Today.”

He revealed that his wife, Cookie, who he had married just a month before his diagnosis, had tested negative, as had the couple’s unborn child - Cookie was just seven weeks pregnant. Their son Earvin Johnson III was born the following year and was not infected.

One of the first sports stars to go public about being HIV-positive, Johnson’s calm delivery of his news in that press conference, complete with his trademark smile, won him plaudits.

Johnson told the assembled media: “I plan on going on, living for a long time, bugging you guys, like I always have.

“I just want to say that I'm going to miss playing. And I will now become a spokesman for the HIV virus because I want people - young people - to realise that they can practice safe sex.”

Johnson said he contracted the virus through unprotected heterosexual sex.

In a Sports Illustrated article published less than two weeks after his retirement, he wrote: “I am certain that I was infected by having unprotected, sex with a woman who has the virus. The problem is that I can't pinpoint the time, the place or the woman.

“I confess that after I arrived in LA, in 1979, I did my best to accommodate as many women as I could—most of them through unprotected sex.”

Johnson told CBS Mornings this week about being part of the 1992 Olympic gold-winning Dream Team, alongside NBA stars such as Michael Jordan and Larry Bird.

“It proved to be the right decision. It helped people who were living with not just HIV and AIDS, but with any disease, that you can live on, you can be — live a productive life."

However, after planning to return to the NBA for the 1992/93 season, Johnson retired from basketball again, after a number of players spoke out against the prospect of sharing a court with him.

He had a brief stint coaching the Lakers in 1993/94, but concentrated on the Magic Johnson Foundation, set up in 1991, to raise awareness about HIV and AIDS and deliver programmes that support ethnically diverse communities.

Read more: Magic Johnson weighs in on issue of unvaccinated players

While there is no cure for HIV, there are are very effective drug treatments that enable people with the virus to live long and healthy lives.

Now a hugely successful entrepreneur and philanthropist, Johnson, 62, told CBS he takes medication once a day, even though his HIV is undetectable, meaning the level in his body is low enough to not be detected by a test.

As a player, Johnson was an NBA champion five times with the Lakers in the 1980s, and won the same amount of championships as an owner of the franchise between 2000 and 2010.

Watch: Yahoo Finance presents... NBA legend Magic Johnson