Chickenpox Vaccination Leads To More Shingles
New modelling research presented at the Health Protection Agency’s annual conference in Warwick confirms that vaccination against chickenpox would significantly decrease the burden of this disease but would lead to more shingles among the elderly.
Researchers also found that vaccinating the elderly against shingles would only partially, but not completely, offset this increase.
Varicella Zoster is a virus that causes two diseases: chickenpox (mostly among children) and shingles (mostly among elderly), this is because the virus remains in the body after chickenpox and is able to reactivate as shingles later in life.
In most cases, chickenpox is a mild illness and around 89% of adults in the UK will develop immunity to the illness. Although a vaccine against the varicella virus (which causes chickenpox) is now licensed in the UK it is not part of UK’s routine childhood vaccination schedule.
If a chickenpox vaccine were to be added to the childhood immunisation programme concerns have been raised that there would be an increase of shingles cases in adults as a result. This is because people who have had chickenpox are less likely to have shingles later in life if they have been exposed occasionally to the chickenpox virus (for example through their children) as this exposure acts as a booster.
Post-vaccination research from countries that routinely immunise their children against chickenpox, including the US, has found an increase in cases of shingles among non-vaccinated age groups.
The Health Protection Agency researchers modelled the impact of vaccinating children against chickenpox (with a two dose schedule) and the elderly (60+) against shingles.
Building on previous modelling data the team incorporated virological, epidemiological and recent data on age-specific contact patterns to see whether a vaccine for the young would impact on the number of shingles in the elderly.
The modelling suggested that a two dose schedule at the levels of coverage likely to be achieved in the UK would lead to an increase of at least 20% of shingles in the medium term (approximately 15-20 years). This increase could be partially, but not completely, offset by introduction of a vaccination against shingles among those aged 60+.
Albert Jan van Hoek, who performed the research for the Health Protection Agency, said; “Our models suggest that vaccination would reduce the burden of chickenpox in the young. However, it will lead to an increase in shingles in the medium term in adults because they will not get that ‘boosting’ effect from being in contact with cases of chickenpox.
“We also looked at whether vaccinating adults against shingles would be of benefit to counteract this. The research showed that a potential increase in shingles could be partly offset by vaccinating the elderly. The success of this, however, depends on uncertain vaccine efficacy parameters, particularly the duration of protection from the zoster virus.
“There are still uncertainties in the research and a lot more work needs to be done examining whether vaccination will be a benefit to all of the population. Also further work needs to be done on the cost effectiveness of any potential chickenpox vaccine before any policy conclusions can be reached.”
The Department of Health has commissioned an expert sub-group of the Joint Committee on Vaccination and Immunisation (JCVI) to look at all the scientific and medical evidence on chickenpox vaccines which will provide its recommendation in due course.