*GRAPHIC CONTENT ALERT* In order to answer the questions well, I have to talk details. Sorry!
She asks, "My character is raped and injected with a drug. Would she need HIV prophylaxis afterwards?"
Boy, we really put our poor characters through so much. But to be realistic in fiction, we need to look at the facts.
After an unprotected sexual encounter, as well as injection drug use (both against the victim's will) we have to worry about several diseases.
Hepatitis C and B are both contracted through bloodborne means. Hepatitis C is more easily transmitted via needles than sex; Hep B is easy transmitted via both routes.
Postexposure Hep B/C treatment: Unfortunately, none exists for Hep C. For Hep B, a vaccine would be given at the time of the evaluation, then one and six months later. They could also get prophylactic Heptatitis B immune globulin. The victim should be tested for both at the time of the evaluation, then a few weeks later. If positive for Hep C, they'd be referred to a specialist for possible treatment.
HIV (human immunodeficiency virus) can be contracted through bloodborne routes assuming several things--the person with HIV has a very high viral count, and the amount of blood transferred has enough virus in it. In the healthcare environment, the risk of contracting HIV from a needlestick exposure to an HIV infected patient is about 3/1000 without taking meds (CDC). So for this victim, worried about HIV and needle exposure, there would be a lot of questions that needed to be answered--how risky was the perpetrator? Was the drug injected like heroin, using a dirty needle, or a clean one?
Sexually, HIV can obviously be contracted, but certain types of sex are more high risk than others. For instance, the person on the receiving end is higher risk; also, anal receptive sex is much higher risk than vaginal because of the risk of tears and bleeding.
Postexposure HIV Treatment: A two or three antiviral drug regimen would be offered to the victim, to be taken for about a month. This is method is not set in stone; the medications can be difficult to take, and the risk of contracting HIV varies widely depending on the exposure, and the HIV risk factors of the perpetrator. The victim would need to be counseled heavily on the risks and benefits of taking the medications.
Other STDs: Sexually transmitted diseases, such as gonorrhea, chlamydia, syphilis and trichomonas are also a concern for rape victims.
Post-exposure STD treatment: Usually a cocktail is offered to the victim that includes treatment for all but syphilis, which can be tested for and treated later. The cocktail includes an intramuscular injection of an antibiotic (ceftriaxone), plus two other antibiotic pills taken for one day (azithromycin and metronidazole).
One last word--emergency contraception is usually offered as well during a post-rape evaluation and treatment, along with counseling and follow up appointments.
Hope this answers the questions, Laura!