Vaccines for preventing herpes zoster in older adults

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Abstract
Herpes zoster or, as it is commonly called, 'shingles' is a neurocutaneous disease characterised by the reactivation of varicella zoster virus (VZV), the virus that causes chickenpox, which is latent in the dorsal spinal ganglia when immunity to VZV declines. It is an extremely painful condition which can often last for many weeks or months, impairing the patient's quality of life. The natural aging process is associated with a reduction of cellular immunity which predisposes to herpes zoster. Vaccination with an attenuated form of VZV activates specific T cell production, therefore avoiding viral reactivation. A herpes zoster vaccine with an active virus has been approved for clinical use among older adults by the Food and Drug Administration and has been tested in large populations. To evaluate the effectiveness and safety of vaccination for preventing herpes zoster in older adults. We searched the following sources for relevant studies: CENTRAL 2012, Issue 7, MEDLINE (1948 to July week 1, 2012), EMBASE (2010 to July 2012), LILACS (1982 to July 2012) and CINAHL (1981 to July 2012). We also reviewed reference lists of identified trials and reviews for additional studies. Randomised controlled trials (RCTs) or quasi-RCTs comparing zoster vaccine with placebo or no vaccine, to prevent herpes zoster in older adults (mean age > 60 years). Two review authors independently collected and analysed data using a data extraction form. They also carried out an assessment of risk of bias. We identified eight RCTs with a total of 52,269 participants. Three studies were classified at low risk of bias. The main outcomes on effectiveness and safety were extracted from one clinical trial with a low risk of bias. Four studies compared zoster vaccine versus placebo; one study compared high-potency zoster vaccine versus low-potency zoster vaccine; one study compared refrigerated zoster vaccine versus frozen zoster vaccine; one study compared live zoster vaccine versus inactivated zoster vaccine and one study compared zoster vaccine versus pneumococcal polysaccharide vaccine (pneumo 23). Confirmed cases of herpes zoster were less frequent in patients who received the vaccine than in those who received a placebo: risk ratio (RR) 0.49 (95% confidence interval (CI) 0.43 to 0.56), with a risk difference (RD) of 2%, and number needed to treat to benefit (NNTB) of 50. Analyses according to age groups indicated a greater benefit in participants aged 60 to 69 years, RR 0.36 (95% CI 0.30 to 0.45) and in participants aged 70 years and over, RR 0.63 (95% CI 0.53 to 0.75). Vaccine-related systemic adverse effects were more frequent in the vaccinated group (RR 1.29, 95% CI 1.05 to 1.57, number needed to treat to harm (NNTH) = 100). The pooled data risk ratio for adverse effects for participants with one or more inoculation site adverse effect was RR 4.51 (95% CI 2.35 to 8.68), and the NNTH was 2.8 (95% CI 2.3 to 3.4). Side effects were more frequent in younger (60 to 69 years) than in older (70 years and over) participants. Herpes zoster vaccine is effective in preventing herpes zoster disease. Although vaccine benefits are larger in the younger age group (60 to 69 years), this is also the age group with more adverse events. In general, zoster vaccine is well tolerated; it produces few systemic adverse events and injection site adverse effects of mild to moderate intensity. Vacunas para la prevención del herpes zóster en adultos mayores El herpes zóster es una enfermedad neurocutánea caracterizada por la reactivación del virus de varicela-zóster (VVZ), el virus que causa varicela, que está latente en los ganglios de la espina dorsal cuando disminuye la inmunidad contra el VVZ. Es un trastorno sumamente doloroso que a menudo puede prolongarse durante muchas semanas o meses y causa el deterioro de la calidad de vida del paciente. El proceso de envejecimiento natural se asocia con una reducción de la inmunidad celular que predispone al herpes zóster. La vacunación con una forma atenuada de VVZ activa la producción de células T específicas y por lo tanto evita la reactivación viral. La Food and Drug Administration ha aprobado una vacuna contra el herpes zóster con un virus activo para el uso clínico en adultos mayores y la misma se ha probado en grandes poblaciones. Evaluar la efectividad y la seguridad de la vacunación para la prevención del herpes zóster en adultos mayores. Se realizaron búsquedas de estudios relevantes en las siguientes fuentes: CENTRAL 2012, número 7, MEDLINE (1948 hasta julio 2012, semana 1), EMBASE (2010 hasta julio 2012), LILACS (1982 hasta julio 2012) y CINAHL (1981 hasta julio 2012). También se examinaron las listas de referencias de los ensayos y revisiones identificadas para obtener estudios adicionales. Ensayos controlados aleatorios (ECA) o ensayos controlados cuasialeatorios que compararan la vacuna contra el herpes zóster con placebo o ninguna vacuna, para prevenir el herpes zóster en adultos mayores (media de edad de 60 años). De forma independiente, dos revisores recopilaron y analizaron los datos utilizando un formulario de extracción de datos. También llevaron a cabo una evaluación del riesgo de sesgo. Se identificaron ocho ECA con un total de 52 269 participantes. Tres estudios se calificaron como de riesgo de sesgo bajo. Los resultados principales sobre la efectividad y la seguridad se extrajeron de un ensayo clínico con riesgo bajo de sesgo. Cuatro estudios compararon la vacuna contra el herpes zóster versus placebo; un estudio comparó la vacuna contra el herpes zóster de alta potencia versus la vacuna contra el herpes zóster de baja potencia; un estudio comparó la vacuna refrigerada contra el herpes zóster versus la vacuna congelada contra el herpes zóster; un estudio comparó la vacuna contra el...

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