In the quarter century since the world first learned about HIV and AIDS, our knowledge on how to fight it has improved by leaps and bounds.

But the myths have grown too. Here we bust 11 of the biggest.

Myth: The very worse thing you can do is have unprotected sex with someone who is HIV positive.

Busted: Obviously you should use protection with an HIV positive partner. But if someone knows they are positive and are on drug treatment, the drugs are so good these days their infectiousness goes down by 96% making them less likely to pass on the virus.

Statistically, you are far, far more at risk if you have unsafe sex with someone who doesn’t know their HIV status.

They may think they are negative. But if they have just got the virus, perhaps after their last negative test a few weeks ago, they are at their most infectious.

This is why testing, and starting treatment, doesn’t just help your health but is a key way we can stop the spread of the virus. It’s also why always wearing a condom is your best line of defense.

Myth: Being HIV positive means you can’t do certain things, like be a nurse or parent.

Busted: There is no job you can’t do if you are HIV positive. And men and women with the virus can be parents to an HIV negative baby. In the UK there’s less than a 1% chance of babies with an HIV positive mum getting the virus.

Myth: I’ve had unprotected sex with the guy and not caught it, so he’s safe.

Busted: You could contract HIV the first time you have unprotected sex or you could have sex without condoms 100 times and get away with it. The risks vary.

After all, if the person you are having sex with is prepared to not use a condom with you, what can make you sure he hasn’t done the same with other guys.

Myth: I’m monogamous, so I’m not in danger.

Busted: This one is going to cause a few rows between boyfriends. But sadly, more gay men contract HIV from their regular partner than do from sex with strangers.

Myth: Some people are just immune.

Busted: This is true. But immunity is incredibly rare, less than a tiny fraction of 1% of the world’s population are immune.

And if you’ve already survived a shark attack, being struck by lightning and a red-back spider bite, your luck is bound to run out soon. In the absence of immunity, safer sex and condom use is a better bet.

Myth: Young gay men are most at risk of HIV.

Busted: Actually young gay men in their teens and early 20s tend to mostly have sex with each other and there are low levels of HIV in this group. If a young man has unprotected sex regularly with older guys, he will be at more risk, because gay and bi men in their later 20s, 30s or older are more likely to have HIV. More men aged over 50 contract the virus than teenagers.

So if you are a 19-year-old guy having unsafe, monogamous sex with your 19-year-old boyfriend, your risk level is low. The big reasons for encouraging young gay and bi men to wear condoms is to get them used to the habit and just in case – after all you never know who your boyfriend has had sex with before.

Myth: Bareback sex is hotter.

Busted: This one is a judgment call. But you have to ask yourself, what matters more – who you are with and what you are doing, or the fact you are wearing a condom.

Myth: HIV and AIDS are the same thing.

Busted: If you know this one is wrong, you would be shocked to find how many people believe they are the same thing, or that ‘an HIV diagnosis is a death sentence’.

Sexual health charity Terrence Higgins Trust just did research of people living with HIV and this came out as the biggest myth, heard by 63% of them.

HIV is Human Immunodeficiency Virus. The virus will cause AIDS, Acquired Immunodeficiency Syndrome, if you don’t realize you are HIV positive and take treatment. This condition is when your immune system is destroyed, allowing other infections and cancers to kill you.

But people who get diagnosed swiftly with HIV can take treatment so they never contract AIDS and have a normal life and normal lifespan.

Myth: You can tell when someone is HIV positive.

Busted: The Terrence Higgins Trust research revealed some of the oddest things people with the virus hear. Among them: ‘Does the treatment make you lose your hair?’ ‘Oh my God! No wonder you’re so skinny!’ ‘That’s impossible – you don’t look like you could have it.’

The virus itself doesn’t make you look any different and the drugs can stop you from getting AIDS and the infections which made people sick, and look sick.

Plus many gay and bi guys, in particular, respond to learning they are positive by taking more care of their general health, going to the gym and getting fit.

Myth: HIV positive people are treated just like everyone else.

Busted: They should be and they often are. But one in three people living with HIV still report they have encountered discrimination in the UK. And in the US research has shown stigma and shame are the biggest barriers to people starting treatment after being diagnosed as HIV positive.

Myth: Scientists are five years from a cure for AIDS.

Busted: They may be. We hope they are. But they can’t possibly tell that. Nobody can.

Amazing research has been done into limiting HIV and eradicating AIDS by incredible people. The same is true of cancer, though, and we haven’t cured that yet. The breakthrough cure could be one of the things already in development or all of those could come to nothing and it could take 25 years – or more.

The stories scientists place in the media, promising a cure in five years, boost their academic reputation and get the research money rolling in. We shouldn’t be cynical about that, as without reputation building and cash, they’ll never find a cure. But we shouldn’t fall for it either.

If you want to learn more about HIV and AIDS, Terrence Higgins Trust’s World AIDS Day page is a good place to start.