This New York Times story is a health column that’s unequivocally in favor of vaccination, and as such it presents information about the vaccine in a somewhat lopsided manner favoring the benefits of the vaccine and downplaying risk.
For example, relative numbers that inflate the benefits of the vaccine are used to describe effectiveness, but there is no quantification of the relatively common and significant adverse effects.
Without giving proper context to the rarity of shingles, especially the incidence of postherpetic neuralgia, and avoiding absolute numbers in terms of benefits and harms related to the vaccine, it is difficult for readers to get a balanced view of the overall utility of this vaccine.
The reporter noted that the “list price is $280 for the two-part shot without insurance.” Since Medicare Part D insurance covered it with a $40 co-pay for each part it is likely affordable for many people.
The story provides relative numbers, noting that the previous shingles vaccine, Zostavax, “reduces the risk of shingles by 51 percent and of PHN by 67 percent”, but this new vaccine, Shingrix “can protect 97 percent of people in their 50s and 60s and 91 percent of those in their 70s and 80s. It also reduces the risk of PHN by 86 percent.”
But what does this mean in terms meaningful to readers, such as absolute numbers? According to a clinical trial published in the New England Journal of Medicine, of the 6,541 people who got the vaccine, 23 developed shingles (about 0.35%). Of the 6,622 who got the placebo, 223 people got shingles (about 3.4%). This difference, of 3.36%, means that for every 29 people over age 70 who get the two-shot dose of Shingrix, one case of the shingles will be prevented. Another way to say this is 28 out of 29 people will see no benefit from the vaccine over three and a half years. The numbers needed to vaccinate to prevent one case of postherpatic neuralgia is more than 200.
The author tells her personal story and a few common harms. She notes that “the shot itself is painful and can cause a sore arm for a day or two. Some people develop immune-related side effects like headache, fever or an upset stomach that last less than three days, according to the manufacturer, GlaxoSmithKline. My only reaction beyond local soreness was an acid stomach for a day or two.”
This is a good start, but the story didn’t recognize that significant adverse effects are actually more common than the benefits, making the story imbalanced.
The study shows that the severity of the side effects of the vaccine were much more intense than what the Times implies. In it, 17% of the patients injected with the vaccine, versus 3% on placebo, had “grade 3” symptoms. These are defined as symptoms that “prevented normal everyday activities.” The absolute rate therefore is 14% or a NNH (number needed to harm) of seven. While the author of the Times story might not have been that sore after the vaccine, according to the data in the trial, for every seven persons injected with the vaccine, one person will have “grade 3” symptoms and have difficulty functioning in everyday activities.
The story doesn’t really tell us anything beyond the fact that there were “studies” that involved 16,000 people. What kind of studies were they? Was there a control group? How convinced should we be by the quality of this evidence?
The story doesn’t acknowledge the possibility of milder cases of shingles, and makes shingles sound very common.
It says that by age 85 “half of adults will have had at least one outbreak of shingles,” but in the study of patients who were older than 70, only 223 people out of more than 6,000 got shingles during a nearly 4-year time span.
The study further noted that “the overall incidence of herpes zoster is 2.0 to 4.6 cases per 1000 person-years but increases with age to 10.0 to 12.8 per 1000 person-years among persons 80 years of age or older.”
Another way to say that? About 1-1.3% of people over 80 develop shingles in a year. While that is a lot of people, that is not nearly as alarming as the prevalence information presented in the Times story.
Study funding is not mentioned. Perhaps more importantly, the story takes an advocacy position in favor of vaccination–and presents the reporter’s opinion as medical advice.
This story compared the efficacy of the vaccine to a previous shingles vaccine. It also noted that the drug acyclovir is used to treat active cases of shingles.
It’s available, and at least partly covered. The story makes this clear.
The story establishes novelty in this way: “studies involving 16,600 people showed it to be far more effective at preventing this disease than the first shingles vaccine, Zostavax, which I had had a decade earlier.”
The story does not appear to be based on a news release.