ZostavaxOverview

Zostavax is the brand name for the shingles vaccine produced by Merck. Patients commonly have many questions regarding this vaccine and the answers to these questions can often be difficult to obtain. That is where we come in!


We have created a question and answer article for the Zostavax vaccine that answers all of the most commonly asked questions! Read on to learn all about the vaccine for shingles and if it could be an option for you!


***2018 Update***

Zostavax is no longer the preferred vaccine for shingles. The CDC now recommends Shingrix for those without contraindications.


Frequently Asked Questions


Question:

What exactly is the Zostavax vaccine?

Answer:

Zostavax is a LIVE attenuated vaccine indicated for prevention of shingles (herpes zoster virus). Live attenuated indicates that the vaccine contains the live herpes zoster virus (as opposed to killed as in many vaccines such as the influenza vaccine), yet it is severely weakened. The positive reasons for using attenuated vaccines are many fold:

  • ​More phases of the immune system are stimulated than with an inactivated vaccine.
  • Reduces or can even eliminate the need for booster immunizations
  • Immunity typically occurs faster than vs. inactivated vaccines.
​​
There are some negatives however to using a live virus. Typically patients that have a compromised immune system cannot have the vaccine. It also must be regulated under strict temperature controls that can make it difficult to transport and store for health care providers.


Question:

What exactly is herpes zoster?

Answer:

Herpes zoster is a viral infection that is characterized by a vesicular (small bumps or bubbles) rash and unilateral radicular pain (radiating type pain). Postherpetic neuralgia, a neuropathic pain syndrome that persists after the rash is healed, is the most frequent complication of herpes zoster.

Question:  

Will my insurance cover Zostavax?

Answer:​

It all depends on your specific insurance carrier. I recommend calling whoever your insurance benefits are through and inquire about it. In most cases, those with a Medicare Part D plan can expect to have the vaccine covered. If it is not covered, the cash price runs a little over $200.00.

Question:

I've already had shingles, can i get it again?

Answer:
Yes, you can get shingles again if you had it before. The virus remains latent (i.e hidden, not causing an active infection) in your body and can reemerge and cause infection for reasons that are relatively unknown. There isn't much evidence that having already had shingles reduces the risk of it coming back. It should be noted that the Zostavax vaccine has not been shown to prevent shingles from RECURRING. It in fact is still recommended by the CDC for patients that have had shingles since there aren't any safety issues with giving to patients who have had shingles.
Question:

Is Zostavax effective?

Answer:
Yes, Zostavax is more effective than placebo in terms of preventing the herpes zoster infection (shingles). When we really get down to the nitty gritty with the numbers, we can truly see how effective the vaccine is. For those that don't need or want to read our in-depth statistical analysis, just know that the CDC has put out the following: Zostavax prevents one case of shingles for every 17 people that get vaccinated. It may also lessen the symptoms of shingles (e.g. pain) if you happen to get the infection after vaccination. Read on for our in-depth statistical analysis or simply skip to the next question!

Zostavax Efficacy Chart

**Warning! In-depth statistical analysis**


​The big number we see here is a listed vaccine efficacy of 69.8%. The 95% CI is a statistical term meaning that based on the results of the study, we are 95% confident that the true efficacy of the vaccine is between 54.1% and 80.6%. The confidence interval is calculated through various methods that we will not discuss here. We really want to know exactly what 69.8% efficacy means.

Firstly, based on the data, we can calculate what is known as absolute risk. Absolute risk in this study is simply the risk of getting infected with the herpes zoster virus (shingles). In the case of the data shown here, we can easily determine the absolute risk of getting shingles in two different groups, the group that received the Zostavax vaccination and the group that did not, otherwise known as the placebo group.

Let's tackle the Zostavax group first. In patients that were vaccinated with Zostavax, 30 people out of 11211 got shingles. That comes out to a miniscule 0.2676%. In patients that were NOT given the Zostavax vaccine, 99 people out of 11228 got shingles, or 0.8817%. 

From here we come up with an important statistical measure known as absolute risk reduction. Another way to put this would be "how much does Zostavax actually reduce my chances of getting shingles?". If we subtract placebo group from the treatment group we come up with 0.8817% - 0.2676%, which equals 0.6141%. This means that getting the Zostavax vaccine reduces your absolute risk of getting shingles by 0.6141%.

This number does not LOOK good to the public or anyone reading the clinical trial results that doesn't understand certain statistical measures It certainly doesn't look as good as the 69.8% efficacy that is stated in the trial data. Clearly, we need to get a better looking number.

​That is where something called relative risk comes in. Relative risk, as opposed to absolute risk, looks at the risk of getting shingles with the Zostavax vaccine group in RELATION to the placebo group. Before, with absolute risk, we were simply talking about the chance of getting shingles. Now we are directly comparing two specific groups, not the whole population.

Relative risk is easily calculated and it can be done a few ways. Very simply, we can divide the absolute risk in the treatment group (Zostavax group) by the risk in the placebo group. In this case, the numbers would be 0.2676%/0.8817% which equals 0.3035. By itself, this number can be hard to describe, so we do one more step and calculate relative risk reduction which is simply 1 minus relative risk.

Inputting the numbers for this we get 1-0.3035 which equals 0.6965, or as a percentage, 69.65%. Ta-da! This number is what the study refers to as vaccine efficacy (it''s slightly off from the 69.8% due to rounding of numbers). It simply means that when comparing the vaccine to the placebo, Zostavax is 69.8% more effective in preventing shingles. It is important to remember that this doesn't mean that since the vaccine is 69.8% effective, you run a 30% risk of getting shingles. It just is 69.8% more effective in preventing shingles when compared to NOT getting the vaccine.

So what is the efficacy of Zostavax?

  • Relative to getting no vaccine, Zostavax is 69.8% more effective in preventing shingles. 
​​
  • Zostavax reduces your absolute risk of getting shingles by 0.8817% to 0.2676% based on this study. This may not seem significant, but when looking at the big picture, it is. There are more than 100 million people aged 50 and older in the United States alone. It is reported that there are around 1 million cases of shingles yearly (which is somewhat close to what this study saw as .8817% of 100 million is 881,700 cases). What if we could reduce the number of cases of shingles by more than half as the vaccine showed in this study? When we are talking about large populations, the significant of the vaccine is huge in terms of the health of patients and in terms of reducing health care costs.
We do want to state that the study in the Zostavax package insert is not the best data to look at. It actually only looked at data for a little over a year, hardly enough to truly measure the efficacy of the vaccine. The CDC has estimated a statistic that resonates much better with the public. They state that Zostavax prevents 1 case of the shingles for every 17 people that get the vaccine. Multiple others studies have shown that it helps with the pain associated with shingles (the post-herpatic neuralgia).

Question:

What are the side effects of the shingles vaccine?

Answer:

Looking at the package insert, this is what is listed for adverse reactions.

Zostavax Adverse Effects

Remember that Zostavax is administered via subcutaneous injection, or in other words, injection directly under the cutaneous layer of the skin. Pain, erythema (redness) and swelling is a common side effect of injections like this and should be expected when receiving the vaccination. The other side effects listed are pruritis (itching), warmth, hematoma (a small collection of blood) and induration (a hardening of skin at the injection site).

One side effect not listed here that you certainly want to take into consideration is the possibility of a small rash near the injection site. If a small rash does occur, it is recommended to cover it until it clears.

Question:

Who exactly is the shingles vaccine indicated for?

Answer:​
The CDC recommends that all adults at least 60 years of age without a contraindication. It is indicated by the FDA for those aged 50 and older without a contraindication. 

The herpes zoster virus vaccine is not recommended for use in people less than 50 years of age.

Question:

Can Zostavax help treat an active infection?

Answer:

No, the vaccine is not indicated for the treatment of an active shingles infection. 

Question:

If I had the vaccine for chickenpox, do I need the Zostavax vaccine?

Answer:

The herpes zoster virus vaccine is not a substitute for the varicella virus vaccine , Varivax.

Question:

Does it help with the pain of shingles?

Answer:

Multiple studies have shown that the vaccine can help with both the severity and duration of postherpatic neuralgia. This is the most common lasting problem that is associated with getting shingles.

Question:

Is the vaccine given in a series or is it just one shot?

Answer:

The need for revaccination has not been defined. Currently, it is a one dose only vaccination.

Question:

Who should not get the vaccine?

Answer:

The herpes zoster virus vaccine is not recommended for use in people less than 50 years of age. It should also not be given to patients with a history of an allergic reactions to gelatin or neomycin.

Patients who have immunosuppression such as people with HIV or patients taking medications that weaken the immune system should not get the vaccine. Ask you pharmacist or doctor if you have questions about the medication you are taking.