Image: Poor Miranda.

Rarely do you see the words “ STI ” and “good news” in the same sentence, but here we are: finally, we have some good news concerning STIs.

More specifically, it concerns the most common sexually transmitted infection in Australia — the one that affects both women and men, with more than half of all cases occurring in the 15-24 year age group.

RELATED: Can you actually catch diseases and STIs from your toilet seat?

Yep, we are talking about chlamydia.

Thanks to Mean Girls, you know how not to spell it.

At the moment, the only way to protect yourself from this common yet nasty bacterial infection is through safe sex with barrier contraception; scientists have been unable to develop a vaccination to quell its spread.

However, thanks to a new study, things are beginning to look promising on the chlamydia prevention front.

As The Verge reports, a research team has recreated chlamydia inoculation trials that took place in the 1960s. This (highly unethical) test failed dramatically because the vaccines, administered to otherwise healthy men, women and children living in countries like India and Ethiopia, didn't actually work.

In some cases, subjects actually became more susceptible to contracting the disease. (Post continues after gallery.)

Popular forms of birth control

Condoms

The male condom is a barrier contraception that prevents both pregnancy and the transmission of STDs. They work by collecting semen so it doesn't enter theman's partner's body. Condoms are 95 to 99% effective at preventing pregnancy.

Diaphragm

Like the male condom, the diaphragm is a barrier method of contraception. It's a shallow silicone dome that's inserted into the vagina andcovers the cervix, which is the entrance to the uterus. It's held in place by the pelvic muscles, and works by preventing sperm from entering the uterus. After sex, diaphragms need to remain in placefor another six hours, in which time the sperm inside the vagina die. This method is 88 to 94% effective at preventing pregnancy, although this rate increases with experience.

Contraceptive pill

The Pillis the most popular form of birth control. There are two types: the combined pill, containing two hormones, and theprogestogen-only, or mini, pill, which only contains one female hormone. The combined pill works by preventing the ovary from releasing an egg each month. The mini pill changes the mucus at the entrance of the uterus, which stops sperm from entering. Both are 99.7% effective; however, they don't offer protection from STDs.

Intrauterine device

IUDs are small, T-shaped devices that are inserted into the uterus by a doctor in order to prevent pregnancy. There are two types of IUD: copper, which affects the movement and survival of sperm in the womb while changing the lining of the womb;and hormonal, which releases progestogen (a synthetic version of the naturally-occurring hormone progesterone) into the uterus. Although IUDs have a success rate of more than 99%, only around 2% of Australian women currently use one.

The female condom

The female condom is a pre-lubricated sheath, which loosely fits inside of the vagina. The condom has a removable ring, which helps to insert the sheath and keep the condom in place. A larger ring remains on the outside to cover the opening of the vagina. They are designed to fit all women and can only to be used once. Due to misuse of the product it is only 79 per cent effective.

Birth control implant

This is a 4cm-longimplant that is inserted into a woman's upper arm, just under the skin, by a doctor. It releases a hormone called etonogestrel, which prevents ovulation and thickens the mucus in the cervix, which can stop sperm from entering. Contraceptive implants - usually sold as Implanon - are removed under anaesthetic every three years, and are close to 100% effective.

Vaginal ring

Vaginal rings are soft plastic rings that contain the same two hormones as the combined pill - oestrogen and progestogen. The ring is inserted into the vagina, where the hormones are absorbed into the body and then prevent the ovaries from releasing eggs. Once inside the ring can't be felt, and it needs replacing every three weeks (with one week's break in between). When used correctly, this method is more than 99% effective.

Depo Provera

Depo is a long lasting hormonal injection. The synthetic form of progesterone is administered every 12 to 14 weeks to woman, preventing pregnancy within this ongoing time period. The injection, which is given in the buttock or muscle of the upper arm, prevents ovulation and thickens the mucus in the cervix, helping to block sperm. The injections are 99 per cent effective but do not protect against STDs. Male contraceptive injections are currently being trialled

The morning after pill

Emergency contraception (popularly referred to as the morning after pill) is used to prevent a pregnancy following unprotected sex. Other reasons include missing a contraceptive pill or a condom breaking. It is common in Australia to use the progestogen-only method. This entails a dosage of EC pills containing progestogen or the synthetic version. A doctor can prescribe the pill or they can be bought over the counter at a pharmacy without a prescription. Emergency contraceptionis 85 per cent effective in reducing the risk of pregnancy.

Sterilisation

Sterilisation is a permanent form of contraception. For women there are two types of sterilisation: tubal ligation, in which clips are placed on the fallopian tubes, or tubal occlusion in which a device is inserted into the tubes. These methods work by preventing the sperm from reaching the egg. Tubal litigation is 99.5 per cent effective. The Vasectomy (for men) works by cutting and blocking the tubes called the vas deferens, preventing sperm from leaving the testicles. The chances of impregnation with a vasectomy are 1 in 1000.

This time around, scientists injected mice with live or dead chlamydia bacteria, chased with a second injection of live bacteria. The mice injected with dead bacteria first were more likely to be infected with chlamydia.

RELATED: The test every single The Bachelor Australia contestant is required to pass.

Essentially, this happened because the dead bacteria suppressed the mice's immune function — which suggests the immune system actually detected the bacteria. Using this finding, the researchers attempted to teach the animals' immune systems, particularly a certain type of white blood cells, that the bacteria should be killed off. (Post continues after gallery.)

Memorable Sex Scenes

Titanic

Titanic.

Friends With Benefits

Friends With Benefits (Castle Rock Entertainment)

Sex And The City

Sex And The City (HBO)

Girls

Girls (HBO)

Bridesmaids

Bridesmaids (Universal Pictures)

American Pie

American Pie (Universal Pictures)