The shingles vaccine appears to be safe for people taking biologic drugs to treat rheumatoid arthritis, psoriatic arthritis and other, similar conditions, according to a retrospective study published in the Journal of the American Medical Association (JAMA).

That’s promising news, as the risk of shingles – a viral infection that causes a painful rash – may be up to two times higher in people with immune-mediated diseases.

Shingles is caused by the the varicella-zoster virus, the same virus that causes chickenpox. After a course of chickenpox, the virus lies dormant in nerve cells, where it is held in check by the immune system. It is thought to flare and cause shingles – also called herpes zoster – when the immune system drops its guard.

The Advisory Committee on Immunization Practices, or ACIP, recommends a single dose of the shingles vaccine for all people 60 years or older; age is a key risk factor for developing shingles. However, both the U.S. Food and Drug Administration and the American College of Rheumatology advise against giving the shingles vaccine to people taking biologic drugs for fear that the vaccine – which is a “live vaccine” and so contains the living virus – would itself trigger shingles. There is also the question of how much the vaccine protects immune-compromised individuals compared with healthy individuals.

The JAMA study authors note that more research is needed, but their findings challenge the idea that the vaccine can trigger the virus in immune-compromised people. “We didn’t find evidence of harm from the vaccine, even among patients who were current users of biologic therapies,” says study author, Jeffrey R. Curtis, MD, associate professor of medicine in the division of clinical immunology and rheumatology at the University of Alabama at Birmingham.

In the study, the research team looked at Medicare charts for 463,541 people older than age 60 who had been diagnosed with rheumatoid arthritis, psoriasis, psoriatic arthritis, ankylosing spondylitis or inflammatory bowel disease. 

They specifically analyzed data on 18,683 of this group who received the shingles vaccine. Of those, 633 patients were taking a biologic drug at or around the time they received the vaccine. The biologics included anti-TNF drugs adalimumab, or Humira, etanercept, or Enbrel, and infliximab, or Remicade, as well as two other types of biologics: abatacept, or Orencia, and rituximab, or Rituxan.