Comment: Researcher challenges shingles-vaccine claims

Dr. Keith Roach’s Your Good Health column (“Vaccine helps prevent shingles complications,” Aug. 23) commits a gross act of statistical indecency, and was deeply misleading to anyone innocently wandering in the pharmaceutical marketplace. A vital dose of reality is needed to prevent anyone from being misled about the value of the shingles vaccine.

A note to Roach from a person identified as D.H. discusses a person who had received the shingles shot years previously, but then got a bad case of the disease. “I thought that if you got the shingles shot, you wouldn’t get the shingles, or at least you’d get only a mild case,” writes D.H. “His has not been a mild case. The doctor told him that the shot just gives a false sense of security. If so, why get the shot?”

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Roach replied that the shot doesn’t offer a false sense of security so much as it’s an incomplete sense of security. “No medical treatment is 100 per cent effective, and that includes vaccines,” he says. “Even the best vaccines don’t work on some people, or can’t be used, which is why having a large proportion of the population vaccinated is so critical for a really infectious disease, like measles.”

Roach then says the shingles vaccine prevents about 50 per cent of episodes from ever occurring, and it might keep others from being worse.

“What might be the most important reason of all to get the vaccine is to prevent the dreaded complication of shingles — post-herpetic neuralgia,” writes Roach. “The rate of post-herpetic neuralgia in vaccinated people who still get shingles is 67 per cent lower than in non-vaccinated people.”

A 2005 study in the New England Journal of Medicine enrolled more than 38,000 people over 60 and reported that, over three years, the vaccine Zostavax “reduces the occurrence of herpes zoster by 51.3 per cent.” This study found 315 shingles cases among those vaccinated and 642 among placebo recipients, concluding that it reduced the rate of shingles by 51.3 per cent.

The impact of the vaccine is measured in “1,000-person years” where the effects are noted among 1,000 people for one year. The study found that the vaccine dropped the rates of shingles per 1,000 person-years from 11.12 (those on placebo) to 5.42 (those given the vaccine).

What this means is the vaccine “helps” (prevents from developing shingles) about 5.7 people per thousand per year (11.12 minus 5.42 equals 5.7).

When you drop from 11.12 to 5.42, that’s about half the rate; specifically, it’s a 51.3 per cent reduction. (This is where Roach gets the 50 per cent.) If you are buying a dress that cost $11.12 and the sign says “51 per cent off” in big bold letters, you will get that dress for $5.42. You’ve saved about half.

But in this case, the vaccine didn’t help 50 people out of a hundred (which is what most people think when you say 50 per cent), it helped five people per thousand per year. Roach’s comments about post-herpetic neuralgia (67 per cent? really?) are similarly exaggerated and those effects are also minuscule.

Roach reassures us with a wonderful understatement by saying “no medical treatment is 100 per cent effective.” In this case, the vaccine doesn’t even come close to being 100 per cent effective when it only “works” for five out of 1,000 people. With 995 people out of 1,000 having no effect (wasting their money on an expensive vaccine and some of them still getting an awful case of the shingles) does this constitute “better than no vaccine”?

Me? I’d rather try bingo, as I’d have probably a much better chance at winning than I would from this vaccine.

D.H.’s doctor seems to have more sense than Roach. This vaccine does indeed deliver a false sense of security.

Here’s my humble prescription for Roach: He needs to spend more time away from his keyboard to examine the research behind the drug industry’s propaganda, instead of misleading his readers by repeating it.

Alan Cassels is a pharmaceutical policy researcher at the University of Victoria and author of Seeking Sickness: Medical Screening and the Misguided Hunt for Disease.

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