A new study from Barcelona, Spain has found that routine vaccinations, such as those for influenza or hepatitis B, are safe for HIV-positive patients who have been successfully treated for the virus using antiretroviral therapy (ART).

The question of whether to give HIV-positive individuals routine vaccinations against illness has been debated, since vaccines can cause temporary increases in viral load. This occurs due to the stimulation of the immune system that is necessary for a vaccine to work.

It had been feared that this increase in viral load might lead to development of resistant HIV strains if a patient were also undergoing ART.

There are also concerns that in people with HIV who have compromised immune systems, a vaccine could backfire and actually cause the disease it is supposed to prevent.

In this study, researchers examined the effects of several different vaccine combinations on successfully treated HIV patients. Patients considered successfully treated were those who exhibited an increased white blood cell count and a low viral load, or amount of virus in the blood.

Study participants received a vaccination schedule or placebo over a time period of one year, after which their ART was halted.

Despite previous reports of vaccinations temporarily increasing viral load, this study found no differences between the group receiving the vaccines versus the placebo group. Both groups experienced some small spikes in viral load lasting less than a month.

Importantly, these spikes in viral load did not increase the risk of developing a resistant strain of HIV. The researchers concluded that they therefore would not affect the progression of HIV in successfully treated individuals.

The study does have some potential flaws. The number of people studied was small (26 total), so the researchers could have missed some effects that would have been observable in a larger group.

Also, the researchers noted that the individuals receiving the vaccines tended to be younger, and might respond differently to the vaccines than an older HIV-positive group. Finally, researchers warn that the results may not apply to individuals whose HIV has not been controlled.

Overall, however, the scientists found that routine vaccines were safe and recommended for successfully treated HIV-positive patients.

For more information, please see the study published in AIDS Research and Human Retroviruses.