A Cochrane review included 13 studies with a total of 69 916 subjects. The largest study included 38 546 participants. All studies included only healthy Caucasian individuals ≥ 60 years of age in high-income countries. Live attenuated varicella zoster virus (VZV) vaccines were used in 10 trials and a new type of vaccine not yet available in 3 trials. The main outcomes on effectiveness and safety were extracted from one clinical trial with a low risk of bias. Confirmed cases of herpes zoster were less frequent in patients who received the vaccine than in those who received a placebo at up to 3 years of follow-up (RR 0.49, 95% CI 0.43 to 0.56; 1 trial, n=38 546), with a risk difference of 2%, and number needed to treat to benefit (NNT) of 50. Vaccine-related systemic adverse effects were more frequent in the vaccinated group (RR 1.29, 95% CI 1.05 to 1.57; 2 trials, n=6 777, number needed to harm (NNH) = 100), but there was no difference in participants with adverse effects hospitalised (RR 1.00 (0.93 to 1.07); 1 trial, n=6616). Side effects were more frequent in younger (60 to 69 years) than in older (70 years and over) participants. One study compared the new adjuvanted recombinant VZV subunit zoster vaccine (not yet available) to the placebo; the group that received the new vaccine had a lower incidence of herpes zoster at 3.2 years of follow-up (RR 0.04, 95% CI 0.02 to 0.10, risk difference 3%; n=8122, NNTB 33).
Date of latest search: 26 Ocotber 2015