Vaccines for preventing herpes zoster (‘shingles’) in older adults
The virus responsible for chickenpox, varicella zoster virus (VZV), can remain dormant inside nerve cells indefinitely. Years later, when immunity declines, for example because of aging, the virus may reactivate and travel through the nerve to the skin surface, producing clusters of blisters distributed along the path of the affected nerve, a condition called herpes zoster but more commonly known as ‘shingles’. This condition is characterised by itching, numbness, tingling, or localised pain, followed by the typical rash. The virus can cause severe pain, which can negatively affect patients' quality of life. In some people, the pain may persist for months or even years after the skin rash has disappeared. The likelihood of developing shingles and the severity of its symptoms both increase with age over 60.
Vaccination for chickenpox, using live varicella virus, has been widely available for administration to children since the mid-1990s. Use of the same virus as a vaccination for adults, for the prevention of shingles, followed about 10 years later, and has been approved for clinical use among older adults by the US Food and Drug Administration. A team of Cochrane researchers based in Brazil has undertaken to answer the question of whether the vaccination for preventing herpes zoster in older adults is safe and effective.
“Treatment of herpes zoster has a significant impact on the health system,” said Anna Gagliardi, the lead author on the review. “But there has been uncertainty about whether the treatments currently in use are really effective.”
The Cochrane Review, published in the October issue ofThe Cochrane Library, examined eight studies randomising more than 52,000 participants. Four studies compared zoster vaccine versus placebo; three others compared zoster vaccines against one another at differing levels of potency, temperature, and activation; and one study compared zoster vaccine to pneumococcal polysaccharide vaccine. Analyses carried out on these data indicate that confirmed cases of herpes zoster were less frequent in patients who received the vaccine than in those who received a placebo. When stratified by age group, the results indicated a greater benefit for participants aged 60 to 69 years when compared with placebo, but also greater susceptibility to adverse effects compared to participants aged 70 years or more.
Based upon these results, the research team found that the results indicate a clear benefit in vaccinating elderly people with the herpes zoster vaccine, with no major safety or tolerability concerns. They also recommend that more research in this area would be beneficial, particularly on the effectiveness of vaccines with lower concentrations of VZV.