Viral load returns quickly to an undetectable level without any change in therapy. Various studies have found that 20 to 60% of patients with viral suppression experience viral load blips (depending on the regimen used and the frequency of viral load testing), and perhaps one-third of these experience repeated blips. Most blips are small, with viral load rising to somewhere between 50 and 1000 copies/ml.
Blips may have various causes, including variability in the testing process, temporary changes in drug concentration, or transient bursts of immune activation, for example due to receiving a vaccine or having an infection such as the flu. One study measured viral load in blood samples from ten patients every three days for four months in two separate laboratories. Nine patients had one or more viral load blips, but only one of the 18 total blips was detected by both laboratories at the same time.1
While a decrease in adherence may cause viral load to rise, most studies have shown that people who experience blips do not have worse adherence than those with consistently undetectable viral load, nor is adherence necessarily lower prior to a blip.2 Further, drug levels before, during, and after viral load blips are often greater than the minimum recommended drug concentrations.3,1
Most clinicians believe that an isolated viral load blip is nothing to worry about. However, multiple blips, or those that start occurring with increasing frequency, may be an early sign of impending treatment failure.
Blips are also not necessarily associated with emergence of drug resistance.4 However, some research suggests that transient viral load increases may be a sign of sporadic immune system activation and might help replenish latent viral reservoirs.5
The relationship between viral load blips and immune recovery is unclear.3 6 Even with the best available therapy and optimal adherence, viral blips can occur. For this reason, guidelines advise that viral load should be checked at least twice to see if the increase is an ongoing trend before deciding whether to change treatment.