Next Wednesday is World Aids Day, and with it comes more reminders that we need to keep ourselves safe.

An HIV particle (not actual size)

Since I work as a volunteer with sexual health charity Terrence Higgins Trust, I think a lot about HIV and how it can – and just as importantly, can’t – be transmitted. Most people know that it can be transmitted through unprotected sex, but there’s some confusion about other routes, like sharing things like toothbrushes or razors. Are they or aren’t they a risk?

A survey published by the National Aids Trust in 2008 said that one in five people didn’t think that HIV could be passed between a man and a woman if they weren’t using a condom. And one in four people didn’t think that it could be passed between two men having unprotected anal sex. More people thought it could be transmitted through biting – which isn’t a risk – than breastfeeding, which is.

How HIV’s transmitted

It would probably help if I went through exactly how HIV is transmitted. As a disclaimer, I should point out that I’m not a doctor, and if you want more specific advice, go to the THT website. There are several ways you can contact them, including both phone and email.

  1. There has to be presence of HIV in the other person. So if you don’t know the other person’s status, then you’re making a big assumption about them.
  2. There has to be an appropriate quantity of whatever fluid contains the virus. A tiny speck of blood, semen or anal mucus is unlikely to hold enough virus to infect you. I say unlikely, because when someone’s first infected, the amount of virus in the fluid can be sky high. After that, the body fights it off and it goes down again.
  3. There has to be an appropriate quality of virus. HIV has difficulty surviving for any length of time outside the body. Any dried blood is unlikely to have any living HIV – which means it can’t infect you.
  4. There has to be a route into the other person. Think about how it would enter the body, bearing in mind that swallowing it isn’t a route. Also, your saliva contains enzymes which neutralise HIV.

Specific threats

So what about specific things – things like sharing a toothbrush? Well, before you pick up someone else’s toothbrush, aren’t you going to rinse it off? Would you notice if there was a lot of blood on it (ie, enough to fulfil number 2 above)? I’ll assume you rinse it off (or you make sure it’s been rinsed by the previous person), in which case any HIV will be gone. And in any case, in number 3, I pointed out that HIV has difficulty surviving outside the body.

Razor? Same thing – surely it would be rinsed by the previous person? And again, it can’t easily survive outside the body.

Oral sex

One of the questions I’ve heard being asked is the chances of transmission through oral sex. First, if they go down on you, it’s almost impossible to get infected. As I said, there’s not enough HIV in saliva to infect you; and even if they’d just brushed their teeth, there almost certainly wouldn’t be the quantity or quality of blood to infect you. And even if there was, how would it get into you?

If you go down on them, there is a slightly increased risk – it’s happened, but rarely. The cum (or vaginal fluid) has to get into you somehow. And since any blood from gums would be coming out, not in, that’s a tall order. Don’t forget, as I said before, saliva kills HIV.

Anal and vaginal sex

Finally, let’s talk about sex: a condom is the best way to protect yourself against HIV infection (and other STIs, and pregnancy, if you’re female). If you use one, and it stays intact and doesn’t come off, then you won’t get HIV that way.

If you have unprotected sex, then you can get HIV. It doesn’t matter if you’re top or bottom, active or passive, cum or don’t cum. You can get it.

Don’t fret if the condom breaks, comes off or you forgot to use it at all. PEP is a course of medication designed to prevent any HIV that entered the body from infecting you. It’s not a guaranteed block, but it gives you a pretty good chance. It has to be started as soon as possible after unsafe sex or a condom not working – and definitely within 72 hours (3 days).

Impossible routes

So while you should be awareof the risks, you should also be aware of what’s not a risk – and that even if something goes wrong, you can do something about it.