Question
Why do UK guidelines only wait 6 weeks to test after PEP?
25 August 2024. Related: All topics, Cure, HIV testing, HIV transmission, PEP/PEPSE.
Why do UK guidelines say 6 weeks for PEP users before testing, while studies monitoring PEP still find quite a few people who seroconvert up to 24 weeks late?
I have also heard of people controlling HIV after treatment. Is this the same as PEP?
Have you heard of the case of the Mitsubishi baby and the French baby?
Does PEP last indefinitely?
Answer
Hi there
As with other Qs about PEP, this is already answered at this PEP link:
https://i-base.info/qa/factsheets/pep-faq
I do not agree with you about lots of people being diagnosed after 24 weeks. Please provide a reference for this as otherwise what you have heard is wrong.
PEP only lasts for the period when you are taking it.
PEP is very different to people who control HIV after a period on treatment. These people, including the Mississippi and French baby involved much longer time than PEP on HIV treatment.
They are also very rare cases where HIV eventually diid come back again. They showed that some people can have a strong immune response to HIV, but that this only works for a while.
Hi Ken, no, this idea about waiting for 24 weeks is wrong, but perhaps look at the guidelines in your country which will also show you are wrong.
The window periods in the US CDC guidelines are the same at the UK. This is 45 days for 4th gen Ab/Ag tests and 90 days for 3rd gen rapid and antibody only tests.
https://www.cdc.gov/hiv/testing/index.html#cdc_testing_type_test-types-of-tests
The UK guidelines, also based on good evidence are here:
https://www.bhiva.org/HIV-testing-guidelines
Both sets of guidelines explain the evidence if you want to go into detail.
I am going to close this discussion now.
It takes 24 weeks to make a conclusion, right? When I read and consulted about it I felt like I was deceived and the test I took was of no use and was meaningless as it could not confirm my negative status. Do I have to wait 24 weeks to confirm my status and is there a high chance that I will be negative after 24 weeks because I was tested for addiction 8 weeks after the last dose of PEP?
Hi Ken, thanks, but you are misreading the results and this is not what the study shows.
The people who seroconverted all had sex again before the HIV test was positive.
The other data in the table show that no-one took more than 24 weeks to seroconvert, and most were detected much earlier.
Please look again.
Have you read all about the study today simon? I read through the study and found the results in the supplementary material section. Do you have any comments on the results of the study? Actually, people there only discovered it after 24 weeks and no one discovered it after 6 or 12 weeks. Is 6 or 8 weeks too early for pep users? I’m also very worried about the situation. your situation but don’t know how?
What do you think about the research linked in the above comment?
Hi there, I am sorry but I don’t understand this comment. I couldn’t find any info about last testing in the link you included to a PEP study from LA.
Please let me know where this info is though if I missed it.
How I can believe in the following testing instructions PEP when there are studies of PEP monitoring, which has not been detected correctly after 3 months. But up to 6 months?
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4151052/#SD1
Hi there, thanks for this discussion.
The i-Base info is based on UK guidelines which are based on UK data about the time taken for tests to show a positive result. Part of the reasons the guidelines changed here is because the 4th generation Ag/Ab tests have become more sensitive.
Partly though it is because public health guidelines are also always a balance for what is practical and this might change in different countries. In the anecdotal data from LA, maybe these 5/1700 results were related to the impact of PEP or PrEP delaying seroconversion.
The UK also encourages routine HIV testing every 3 to 6 months for people who are sexually active or at risk, and this would pick up rare cases when seroconversion takes longer than 24 weeks.
In 2024, PrEP is also widely used here and is available free on the NHS. This depends on routine HIV testing which would also pick up these cases.
They is also an ethical aspect to making people wait for 6 months, with all the resulting stress and anxiety, when it is easy to be confident that they are almost certainly HIV negative. Sexual health clinics run over one million HIV tests every year and more than 99% are negative.
Please can you send a link to the study from LA in 2015 – which in now 9 years old. Otherwise it is difficult to comment without full details.
As discussed above about the UK guidelines saying 6 weeks after PEP is conclusive while follow-up studies still detect seroconversion after 24 weeks which are two studies by a clinic in Los Angeles was opened in 2015 in which more than 1,700 people came for pep and up to 17 people seroconverted. Among those who seroconverted, the time was greater than the time current guidelines of other countries. In that study, people were tested at the time points 2, 4, 12 and 24 weeks and both did two tests: 1 rapid antibody and 1 NAT (NAT can detect earlier). ag/ab)
I remember about 5 people finding out after 24 weeks (which means the tests at 2, 4 and 12 weeks were wrong (or masked by PEP). If 5/1700 estimates globally are wrong then what will the missed number be since recent studies use a 12-week period. Then if HIV is discovered after 12 weeks do they all default to this being called a new exposure?
I have used PEP and I am waiting for the 24 week test. But when I read those studies, I no longer believe in them because they are positive but they just want to give the earliest instructions without thinking about the safety of the patient. citizens and ensure accurate testing times.
The same is true of your country’s guidance. In 2011, you gave guidance of 4 months and by 2021, it will be reduced to only 6 weeks. But the time for a person to develop enough to detect it has not shortened.
I’m talking about your country’s guidance in 2011 and 2021 which are both based on 4th generation testing.
I look forward to your answer and posting it on this website for everyone to refer to!
Thank you very much