Baseline Screening
Once someone finds the right PrEP prescriber and they agree that PrEP is a good option for them, the prescriber will run a series of tests on them (blood, urine, and possibly swabs) before providing them with a PrEP prescription. These include:
Baseline tests to measure things like kidney function so that they can see if PrEP use results in unintended side effects over time
Tests for sexually transmitted and blood borne infections (STBBIs), so that a person can be treated if necessary
And, most importantly, HIV tests to confirm that someone is HIV negative before starting PrEP
Why is confirming HIV status so important?
While the two HIV medications found in PrEP (TDF & FTC) are effective enough on their own to prevent HIV infection in HIV-negative individuals, they are not effective enough on their own to treat existing HIV infection in people who are living with HIV. For people living with HIV, the medications in PrEP are often paired with a third medication so that they can effectively treat HIV.
Therefore, if someone is living with HIV but is unaware of their HIV status and they start PrEP, the medication will not be effective at treating the HIV in their body. When this ineffective medication exists in the body alongside HIV, over a period of time the HIV virus can build up a resistance against it. In this case, HIV would no longer respond to the two types of HIV medication used in PrEP. As these medications are common components of many HIV treatment combinations, this means that the person would lose many of these treatment combinations as options, limiting their HIV treatment options in the future.
What does this involve?
To confirm someone’s HIV status, they will receive an HIV blood test. As it can take up to three weeks after an HIV infection for commonly used tests to detect it, the person should refrain from activities which could result in HIV infection such as sexual activity or sharing drug equipment for at least three weeks before the test. This is important to ensure that the result is accurate.
If someone doesn’t refrain from these activities for at least three weeks prior to testing, their PrEP prescriber may ask them to return at a later date, delaying their access to PrEP. Someone’s PrEP prescriber might also ask them to return for follow-up testing in 1-3 weeks’ time if they’ve experienced any symptoms which might be related to acute HIV infection. You can learn more about these here.