Covid Vaccines for Immunocompromise — Additional Dose or Booster Dose?

Betty Chaffee/ November 3, 2021/ immunization, vaccines/ 0 comments

Somehow, the terms "additional dose" and "booster dose" for Covid-19 vaccines have become interchangeable. I heard an expert from CDC say on a national webinar that they were only using the term "booster" to refer to both. Some doctor's offices are doing that, too. But if you're one of the many Americans who happens to be immunocompromised, terms matter. You need to know the difference between the two, because you may need both. Let me explain.

What's the difference between an additional dose and a booster?

Experts found that weak immune systems didn't respond as well to the two-dose initial series of Covid-19 mRNA vaccines. If you're immunocompromised, you now need a three-dose series to make sure your body generates a protective immune response.  The first two doses are given at the authorized interval of three or four weeks, and the third four weeks after the second. The third dose of the series is often referred to as an "extra dose" or "additional dose". And it's only for the mRNA vaccines made by Pfizer/BioNTech and Moderna.

Experts also found that once you have a protective immune response to the mRNA vaccines, immunity begins to wane over several months. So a "booster" dose is recommended for many groups of people. The booster dose does just what it says, it boosts immunity back up to the initial protective level.

Why do the terms really matter?

Using the right term matters for three reasons. First, if you're immunocompromised, you may need a total of four vaccine doses. Three initial doses to generate an adequate initial response, then a booster six or more months later. Your vaccine provider will need to know why you're requesting a fourth dose when most people only need two or three doses.

The second reason is that one of the vaccines (Moderna) uses a lower dose for the booster than for the initial doses. If you're getting the Moderna vaccine, using the term "additional dose for immunocompromised people" will get you the full dose. The term "booster" will get you the lower dose. You deserve to have the right dose at the right time.

And finally, CDC recommends that the entire initial series be made up of the same vaccine. So if your first dose was Pfizer, your second and third should be Pfizer too. Same with Moderna. But the recommendation for boosters is different - everyone is allowed to "mix and match" vaccines for their booster dose. So your additional dose should use the same vaccine you started with, but you can choose any of the three available vaccines for your booster.

What if you got the Johnson & Johnson vaccine?

Recommendations for the Johnson & Johnson vaccine don't differentiate between those who are immunocompromised and those who aren't. If you had J&J you're eligible for a booster at least 2 months after your first dose. An "additional" dose isn't recommended, even if you're immunocompromised. But you can choose to get a different vaccine for the booster dose if you want to.

Wondering if you fit into the "immunocompromised" category?

The CDC has explained what health conditions and medications weaken the immune system enough to be considered immunocompromise. This list contains many of the medications that weaken the immune system. But in the end, if you're not sure, talk with your doctor or pharmacist about your medical history and the medications you take. Share in the decision about risks and benefits so you can do what's right for you.

As always, please share your questions and comments in the section below. Or contact us directly at BetterMyMeds. We love hearing from you!


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About Betty Chaffee

Betty Chaffee, PharmD, is owner and sole proprietor of BetterMyMeds, a Medication Management service devoted to helping people get the maximum benefit from their medications.

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