Remember a few weeks ago I wrote about THIS problem?
About 2 weeks ago, the FDA approved Shingrix, a new vaccine for the prevention of shingles in people aged 50 years and older. They also took the very unusual step of stating that people should get Shingrix rather than Zostavax, the only other vaccine available to prevent shingles.
Not only did the FDA state a clear preference for Shingrix over Zostavax, they also recommended that people who have already been vaccinated with Zostavax should be RE-vaccinated with Shinrix.
To my knowledge, the FDA has never done this, showing such a clear preference for one vaccine over another, to the point of saying that a previous vaccination is essentially invalid. Why would the agency do this?
It is much more effective than Zostavax
In the clinical studies, Shinrix was well over 90% effective in preventing shingles and its most devastating consequence, postherpetic neuralgia, in all age groups. By contrast, Zostavax is only 18-64% effective, and is least effective in patients over 80 years of age, who are at greatest risk of a shingles outbreak.
The protection lasts longer
The protection given by the Zostavax vaccine has not been evaluated in long-term studies. I found a reference to one long-term study of Zostavax that is supposed to be completed in 2024. However, no studies that I could find have followed people who received Zostavax longer than about 2 years. (Any science types out there who can find one, please post it in the comments!)
Shingrix studies, by contrast, were carried on for up to 5 years and showed that the vaccine remains effective for prevention of both shingles and postherpetic neuralgia. The question remains, though, will the protection be lifelong? After all, if you vaccinate someone at age 50 they have hopefully MANY more than 5 years to live shingles-free.
No live virus
Shingrix is not a live virus vaccine, therefore there is no restriction on vaccinating people who are immune compromised or live with someone who is immune compromised.
What are the downsides of vaccinating with Shingrix rather than Zostavax?
Two shots, not one
The Shingrix dosing schedule calls for a second, booster dose of vaccine 2-6 months after the first dose. This may be a problem with Medicare, because there are no Medicare-covered vaccines that call for a second dose within one year. We will have to see how the coverage determinations shake out at the Medicare level.
Much higher rate of side effects
Shingrix’s package insert reports over 50% of patients who received the vaccine complained of body aches, fatigue and headache afterwards. 88% of people reported pain at the injection site (compared with 14% of people who got a placebo shot). Recipients also reported fever, shaking chills and GI symptoms in fairly large numbers.
Younger people had more problems than older people, probably because they were making a more robust immune response.
A LOT of vaccine
From a population health standpoint, a 90% effectiveness rate sounds fantastic. However, from a cost standpoint it might not be so great. Here’s a crash course in how we determine how many people you have to treat in order to prevent an illness or condition.
For Shingrix, 11.1 people aged 80+ got shingles in 1000 person-years if they did NOT get the vaccine, and 1.0 people if they did. That’s great, right? 90% effective. But in order to determine how many people you need to vaccinate to prevent one case of shingles, the math is different. It’s 1 divided by the difference in ABSOLUTE risk. 1/((11.1-1.0)/1000)
You need to vaccinate 99 people over age 80 in order to prevent one case of shingles over 5 years. That’s a LOT of vaccine, but much better than 435 patients with Zostavax.
The bottom line
Shingrix isn’t even available to order yet for doctors’ offices and pharmacies, and already it’s creating a stir. The unprecedented endorsement by the FDA favoring Shingrix over Zostavax will likely force Zostavax off the market soon.
Shingrix IS much more effective than Zostavax at preventing both shingles and postherpetic neuralgia. That higher effectiveness comes at the cost of being a more uncomfortable vaccine to receive, and having two get two shots instead of one.
If the goal is preventing shingles, Shingrix is clearly the way to go. I will hit the age to be eligible to receive the Shingrix vaccine in a few years. Will I get it? Probably, because I’ve already had one bout of shingles and I really don’t want to have it again.
QUESTION: Have you had Zostavax? Will you get Shingrix?