Shingles vaccine - why?
Another day, another vaccine. We seem to have had a rush of them in the last few months - in August last year I wrote about the new plans to immunise all children aged two to 17 against flu every year ; in September it was the turn of pregnant women, who are now being advised to get immunised against whooping cough. Now the Joint Committee on Vaccinations and Immunisations (JCVI) is recommending a new national vaccine strategy for all 70-79 year olds, this time against shingles, or herpes zoster.
Shingles is an infection caused by a virus - the varicella zoster virus. It's the same virus that causes chickenpox. Once you've had chickenpox, the virus can live on in the nerve roots next to your spine. At any stage later in life - often decades later - the virus can be 'reactivated', causing the burning pain and band of painful blisters and scabs on one side of your body. That means you don't actually 'catch' shingles - but anyone who's had chickenpox is at risk of getting it.
Why not just immunise children against chickenpox, cutting the risk of chickenpox and shingles together? Well, immunisation often doesn't last a lifetime, and stopping children getting it young might just mean they got it more often later in life. Oddly, the fact that kids get chickenpox may partly protect adults against shingles, since it seems that some adults are exposed to the chickenpox virus later in life, boosting their immunity against getting shingles (ref 1,2).
Why vaccinate against shingles at all? Shingles can be a really nasty condition - while most people recover completely, some people get very severe nerve pain, called post-herpetic neuralgia, that can go on for years. Others get infection around the eye, which is not only painful and distressing but can also, occasionally, cause blindness.
Why this age group? Firstly, the chance of getting shingles goes up as you get older - probably because your immune system, which normally fights off infection, gets weaker with age. Secondly, complications from more shingles are more common among older people - up to one in four over-60s gets long-term nerve pain. Unfortunately, as you get older still, the vaccine is not as effective (ref 3), so giving it to over-80s might not protect them in the same way. If it's given to 60-69 year olds, it's not clear whether the protection would last long enough to prevent the more common complications in the over-70s and over-80s.
Of course, money comes into the equation, as it should in these times of increasing cuts in the NHS. If a vaccine only protects half as many people because it's not as effective in an older age group, it basically costs the NHS twice as much to get the same benefit. Is it a 'magic bullet'? No - studies suggest that vaccinating over-60s cuts their risk of getting eye complications by about 65% and of getting ill with shingles by 55-60% (refs 4,5), rather than protecting completely. Would I recommend it? This week in surgery I saw a delightful patient whose last eight years - and most of her retirement - have been ruined by neuralgia after a bout of shingles. If I can help people like her by recommending the vaccine, I won't hesitate.
1) Thomas SL, Wheeler JG and Hall AJ (2002) Contacts with varicella or with children and protection against herpes zoster in adults: a case-control study. Lancet 360(9334): 678-82. http://www.ncbi.nlm.nih.gov/sites/entrez/12241874
2) Gershon AA, LaRussa P, Steinberg S et al. (1996) The protective effect of immunologic boosting against zoster: an analysis in leukemic children who were vaccinated against chickenpox. J Infect Dis 173(2): 450-3. http://www.ncbi.nlm.nih.gov/sites/entrez/8568309
3) JCVI statement on zoster vaccine http://goo.gl/lZ0nf
4) Tseng H et al. JAMA, January 12, 2011. 305(2): 160-166
5) Oxman M et al. n engl j med 352;22: 2271-2284