The results of a phase 3 clinical trial have just been published, and show that an experimental shingles vaccine has been successful in older adults. Considering the long-term pain that shingles causes, this is promising news.
In Brief: Shingles
Shingles is an infection that can occur in people who have previously had chickenpox. Dormant remains of the chickenpox virus become reactivated and begin to affect the nerves and skin. This commonly takes the form of a painful rash, but can also result in a complication called “post-herpetic neuralgia” (PHN). This is a nervous issue that can result in long-term pain, even after the rash goes away. Shingles infections usually go away within a matter of weeks or months, but some cases have been known to last for years.
There is an existing shingles vaccine, called Zostavax, which can reduce a person’s risk of developing shingles by around 50%. However, the vaccine wears off after about five years, and a 50% reduction, while good, definitely leaves room for improvement.
In Brief: Clinical Trials
Human clinical trials progress through three phases. Phase 1 is meant to establish dosage levels, phase 2 tests for safety and how well the drug works in ideal conditions, and phase 3 tests safety and how well the drug works in real-world circumstances. A phase 3 trial is the last step before FDA approval can be sought for a treatment.
The Experimental Vaccine
The experimental vaccine, called HZ/su (sexy brand names tend to come later), attempts to stimulate active immunity. This means that it uses a weakened piece of the live virus, combined with an adjuvant (ingredient to enhance immune system response), to create a strong and long-lasting immunity to the disease.
HZ/su’s phase 3 trial featured 13,900 adults, aged 70 or over, and took its population from 18 different countries. Participants were given either the vaccine or a placebo, and were monitored for four years. During this period, the placebo group developed 223 cases of shingles. In the vaccine group, only 23 did.
Some short-lived side effects were also observed. These took the form of fatigue, muscle pain, or pain around the injection site, and they lasted around seven days after injection.
What This Means
The painful rash of shingles can cause significant suffering in older adults, even when ignoring the possibility of post-herpetic neuralgia. The HZ/su shingles vaccine has gone through the rigorous clinical process, and its results are both promising and close to being a reality for patients. It is probable that the vaccine’s creators will seek FDA approval at some point in the near future.
Cunningham, A., et al., “Efficacy of the Herpes Zoster Subunit Vaccine in Adults 70 Years of Age or Older,” New England Journal of Medicine, 2016; 10.1056/NEJMoa1603800.