Researchers looked at whether or not a two-dose recombinant zoster vaccine would reduce the incidence of herpes zoster in patients with hematologic malignancies after autologous stem cell transplantation.
Use of a two-dose recombinant zoster vaccine significantly reduced the incidence of herpes zoster among patients with hematologic malignancies after autologous stem cell transplantation (ASCT), according to phase III data published in JAMA.
Data showed an incidence rate ratio (IRR) in participants who completed both doses of the vaccine equivalent to a vaccine efficacy rate of 68.2%.
“The efficacy in this transplant population was lower than in nontransplant populations aged 50 years or older (91%), which may reflect a weaker immune response due to underlying hematologic disease and the high-dose preparative regimens given prior to autologous HSCT,” wrote Adriana Bastidas, MD, of GlaxoSmithKline, and colleagues.
“Nevertheless, the overall efficacy in participants who received at least one dose appeared very similar to that of a heat-inactivated varicella-zoster virus vaccine administered to a similar population,” they wrote. “However, this level of protection was achieved by a four-dose schedule of the heat-inactivated vaccine compared with a two-dose schedule of the recombinant zoster vaccine.”
The study enrolled 1,846 transplant recipients from 167 centers in 28 countries. Participants were randomly assigned to receive two doses of either recombinant zoster vaccine (n=922) or placebo (n=924). Vaccines were given in the deltoid muscle, with the first dose given 50 to 70 days after transplant and the second 1 to 2 months thereafter.
Patients were excluded if they had HIV infection or vaccination against varicella or herpes zoster in the previous year.
Of the total population, 94% received two doses and 74% completed the study. The most common underlying disease was multiple myeloma (53%), followed by non-Hodgkin B-cell lymphoma.
During the 21-month follow-up period, 49 participants assigned the vaccine were diagnosed with at least one herpes zoster episode compared with 135 assigned to placebo (30 vs. 94 per 1,000 person-years). This translated to an IRR of 0.32 (P<.001).
There was also a significant reduction in incidence of postherpetic neuralgia (P=.02) and other prespecified herpes zoster-related complications (P=.02) among patients assigned to the vaccine arm, compared with placebo. In addition, patients given the vaccine had a shorter duration of severe herpes zoster-associated pain (892.0 vs. 6,275.0 days; HR=0.62; 95% CI, 0.42–0.89; P=.01).
“The recombinant zoster vaccine induced strong humoral and cellular immune responses, which were significantly higher than in the placebo group, consistent with previous observations,” the researchers wrote. “One month after dose two, all recombinant zoster vaccine recipients had detectable glycoprotein E–specific antibodies, and although the levels subsequently decreased, as previously observed in older adults, they remained higher than baseline 24 months after dose two.”
Overall the vaccines were well tolerated, with mild and transient symptoms. Injection site reactions occurred in 86% of patients assigned to the vaccine and 10% of patients assigned placebo. Similar rates of unsolicited and serious adverse events, potentially immune-mediated diseases, and underlying disease relapses occurred in both groups.
The researchers acknowledged that the study did not assess long-term protection after the second year, and that this outcome merits further consideration.