Q and A


Why has my viral load gone up after a vaccine?

Hi everybody, I’m on treatment with Biktarvy since I found out I was HIV positive 1 and a half years ago. I’ve always been undetectable, except for the last time, 2 weeks ago, when they found I have VL 251 (which it seems really high to me).

I’ve never missed a single pill. I’m very worried this could lead to virological failure and the virus becoming resistant to one or more drugs. The doctor told me I should repeat the viral load in 3 months, so on September 2022.

I don’t know if this could be important: about 25 days before I had my viral load checked, I got anti-hepatitis A and chickenpox/measles/mumps/rubella vaccination. Thanks if you can answer, you all do a great job here.


Hi, how are you doing?

Your doctor is right to suggest getting a repeat test. This will rule out if this is a true viral failure – this is not likely.

The vaccines you have mentioned are likely to be the cause for this blip in viral load. At your next test, any affect these vaccines will have had would have worn off. Hopefully you will return to being undetectable.

It is also possible this was a blip. These are common events whereby viral load increases but returns to being suppressed. These are not triggered by an event and can be regular part of HIV treatment.

Di you have your CD4 count done at the same time?



  1. Josh Peasegood

    Hi Tee, in these cases U=U can still apply. This is usually isolated and viral load will return to below 200 shortly. This minimises the time for sexual encounters while viral load is above 200.

    In this case, a viral load of ~250 is still significantly suppressed. Transmission at this low of viral load is very rare, if heard of at all.

    It is likely that this is not listed as a precaution to not deter people from getting vaccines. Vaccines are still a significant part of someone’s healthcare. There is much more risk to health than a very small blip in viral load to someone choosing not to have a vaccine for this risk.

  2. Tee

    Does this mean that the person is infectious and able to transmit the virus, and if so why is it not known when it comes to U=U and being vaccinated as a precaution.


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