Shingles risk is increased after this type of stem cell transplantation, and a vaccine that contains a weakened live strain of the shingles virus isn't recommended for these immunocompromised patients.
This randomized clinical trial conducted in 28 countries included 1,846 patients who had undergone stem cell transplantation; 922 to receive two doses of the vaccine within a few months after transplantation and 924 to receive a placebo.
During a follow-up of about 21 months, at least one episode of shingles was confirmed in 49 patients who received the vaccine compared to 135 patients who received placebo (an incidence of 30 cases per 1000 person-years after two doses of the vaccine compared with 94 per 1000 person-years after placebo).
The difference was statistically significant. A limitation of the study is that long-term protection from the vaccine wasn't assessed.