Why Everyone Has At Least Some Risk of Shingles

and why you may want to consider getting the shingles vaccine even if you are less than 50 years old

Theoretically, if you have never been exposed to the chicken pox virus, otherwise known as the varicella zoster virus (VZV), you cannot get shingles (Herpes Zoster) because shingles is a reactivation of the chicken pox virus that stays dormant in your body.

Now most people who are still living today have either had chickenpox itself or had the chickenpox vaccine as a child. The data out there says that over 99% of people born before 1980 have had chickenpox so that means all these individuals can eventually get shingles. So if you are at least 43 years old and don’t recall getting chickenpox, you probably did and survived it….

And then starting in the 80s, some children started to get vaccinated with the chickenpox vaccine. In the US, it started in 1995 and in Canada, it started in 2002.

But what if you never got chickenpox because you got the chickenpox vaccine? Are you still at risk of getting shingles?
The answer is yes, because the chickenpox vaccine is a live attenuated vaccine that contains the same virus that causes chickenpox. It just cannot cause a healthy immunocompetent person to develop the primary chickenpox infection because the virus has been weakened (“attenuated”). Nonetheless, the vaccination itself means the body gets exposure to the virus, which will then stay dormant in the body, just like the actual chickenpox virus does.

There are many risk factors that increase the risk of developing shingles and one of them is age. Actually, age is one of the most important risk factors - the older you are, the higher your risk of developing shingles. With increasing age, the body’s cell-mediated immunity (a component of the immune system) declines and this cell-mediated immunity that keeps the chicken pox virus in check starts to wane and when that happens, the virus can reactivate and cause shingles. Of course, it doesn’t mean that you will get it, just that you are more likely to compared to someone who is younger. I have a number of patients currently in their 90s that to date, still haven’t had shingles. My grandma made it to 97 years old and never got shingles. The point is that statistically, your risk is just higher with increasing age and generally speaking, most people who get shingles are at least 50 years old.

What if you’re younger than 50? Can you still get shingles?
Absolutely. Shingles can technically occur at any age as long as your body’s been exposed to the virus previously. In fact, shingles can occur in kids as well and that’s called pediatric herpes zoster. It’s pretty rare but it does occur. I even met a physician the other day who said he had encountered an 11 year old patient who got shingles. Usually though, it doesn’t occur in kids unless they had chickenpox in their first year of life, they were exposed to it in the womb during the mother’s pregnancy or they are extremely immunosuppressed. The good news is that the chickenpox vaccine is associated with a lower risk of getting shingles during childhood compared to getting the actual chickenpox infection itself.

I do have a handful of patients who got shingles in their 20s, 30s and 40s though. The reasons for getting it so young are likely multi-factorial but one of the biggest risk factors is being immunosuppressed or immunocompromised. Just like increasing age is associated with a decline in cell-mediated immunity, being immunosuppressed either by disease/condition or by immunosuppressive medication is associated with the same thing. But not all immunosuppression is created equal so the more immunosuppressed you are, the higher your risk of getting shingles. In fact, high immunosuppression is associated with a 40% increase in risk compared to low immunosuppression.

What is considered high immunosuppression?
Individuals who have had hematopoietic stem cell transplants or solid organ transplants or have hematopoietic malignancies or HIV are considered to be highly immunosuppressed. In fact, stem cell or solid organ transplant recipients have a 9 to 10-fold higher risk of getting shingles compared to the general population. Other autoimmune diseases like rheumatoid arthritis, systemic lupus and polymyalgia rheumatic are associated with a 2-fold greater risk of shingles.

And then there are medications that suppress the immune system and these include cancer treatments, some biologics, systemic corticosteroids and other immunosuppressants like azathioprine, cyclosporine and methotrexate to name a few. These drugs all vary in their degree of immunosuppression so again, the more immunosuppressive a drug is, the greater the risk of shingles.

So which drugs are associated with the highest risk? Generally speaking, biologics and cancer treatments are associated with a higher risk of shingles than most other immunosuppressants used to treat rheumatic diseases or other inflammatory/autoimmune conditions (eg. methotrexate, azathioprine, etc.). Biologics are a class of drugs of derived from living organisms - they are generally pretty expensive, injected subcutaneously into the body or administered intravenously and most of them are proteins. Note that not every biologic suppresses the immune system - it really depends on which part of the body the drug is targeting. In the case of biologics used to treat rheumatic, inflammatory or other autoimmune diseases, they generally target and therefore, suppress the immune system. There is one biologic out there that is particularly more immunosuppressive and that one is called rituximab, which is used to treat a number of conditions like rheumatoid arthritis, vasculitis, multiple sclerosis and some lymphomas, to name a few. Interestingly though, there is also a class of biologics called TNF inhibitors (eg. infliximab, certolizumab, adalimumab, etanercept, etc.) where the risk has been debatable with some studies reporting an elevated risk of shingles and some that do not. But even within this class of TNF inhibitors, the degree of immunosuppression is different as well with studies showing infliximab being associated with the highest risk.

Then there is a NEWER class of drugs called JAK inhibitors (e.g. upadacitinib, tofacitinib and baricitinib) that is about twice as likely as a biologic (except rituximab) to cause shingles. In fact, it is generally recommended that anyone about to start on a JAK inhibitor be vaccinated with the shingles vaccine prior to starting therapy. So if I had to rank drugs from highest to lowest risk, it would probably be (I say probably because they haven’t all been compared head-to-head so it’s really an estimate):

rituximab, JAK inhibitors > other biologics, cancer treatments > other immunosuppressants (like methotrexate, azathioprine, cyclosporine, etc.)

What about steroids (=systemic corticosteroids)? Examples include oral prednisone, prednisolone, hydrocortisone, etc. These are a bit of harder to place because it really depends on the duration of exposure and the cumulative dose. Long-term exposure to small doses can amount to a large cumulative dose which could very well be moderate suppression and would place someone at a much higher risk than very short term exposure to a large dose for a week or two.

So what’s my risk of getting shingles? Generally speaking, the lifetime risk is 20-30%. Shingles is just more likely to occur starting at 50 years old and can only increase with increasing age or with increasing immunosuppression either by disease or by immunosuppressive medication. The shingles vaccine that is currently available in North America is the recombinant non-live herpes zoster vaccine otherwise known as Shingrix. You may have heard of Zostavax as well - that one was the live attenuated zoster vaccine that has been discontinued in North America as of 2021/2022. However, the live zoster vaccine made by different pharmaceutical companies is still available in some parts of the world…like Korea, Japan and Thailand.

So should I get the Shingrix vaccine?
If you are at least 50 years old, you should get the Shingrix vaccine.
If you are at least 18 years old and are immunosuppressed by disease or medication, you should get the Shingrix vaccine.

Unfortunately, the vaccine hasn’t been studied in <18yo so generally it’s not recommended in this specific population.

What if I previously got Zostavax?
You should probably get the Shingrix vaccine if it has been at least 1 year since you got Zostavax, to maximum your protection. The reported vaccine efficacy with Zostavax was 70%, 64% and 38% depending on age whereas with Shingrix, we know that the vaccine efficacy was well over 90% in the original trial that looked at immunocompetent individuals at least 50 years of age. Whereas vaccine efficacy waned significantly with Zostavax (<35% at 6 years post-vaccination, 21-32% by 7-8 years post-vaccination), there is interim data from a long-term follow up study that reports a Shingrix vaccine efficacy of 89% overall for up to 10 years post-vaccination.

What if I have already had shingles? You can still get shingles again unfortunately. The vaccine can offer protection but the infection does not. To date, I have seen someone get it 4 times over a span of 3-4 years. And if you’ve had shingles previously, you are at a higher risk of getting it again. Expert opinion around the world is that you wait at least 1 year from the time of infection before getting the shingles vaccine but waiting until the acute disease and symptoms are over is also a possibility as well.