Q&A: Booster shots with Duke infectious disease expert

Q&A: Booster shots with Duke infectious disease expert



By Elizabeth Thompson 

COVID-19 boosters. They were introduced to the public a couple of months ago, but for many people, there is still a lot of confusion over what they are and who needs them. 

As we approach the holiday season, when many people will reunite with family and friends they may not have seen for over a year, having as much protection for themselves and their loved ones is a priority. But who should get a booster? And which one should they get?

North Carolina Health News sat down with Cameron Wolfe, associate professor of medicine at Duke University School of Medicine, who specializes in infectious diseases, to ask all of your questions. Answers may be edited for grammar and brevity.

NC Health News: What is a booster shot, and why do some people need it?

Cameron Wolfe: The concept is simple — can I top up your immune system’s defense, which naturally over time tends to wane. What we’re seeing with COVID is, unfortunately, the vaccines, like most other vaccines, do tend to have diminished benefit over time.

Folks who are either older and have an immune system that tends to be what we call immunosenescence, or just a little bit more stagnant and forgetful. They tend to lose their defenses a little quicker. 

Same is true for folks who are immunosuppressed. 

When you then combine those things together with folks who are either exposed more frequently to COVID, for example, health care workers, or folks who have greater risk if they were the unlucky one or two who have diminishing immunity, who’s going to get more severe cases, this idea of saying “Hey, maybe there’s a subsection of community who really can help bolster their defense.” 

The idea is simple enough. It’s that across the whole population, there’s different paces at which our defense wanes, and can we find certain people there who need a top up. That’s not really different than what we do each year for flu vaccines, it’s what we do with pneumonia vaccines. 

NCHN: What is a valid pre-existing condition for a booster shot? Do mental health conditions count? What does it mean to be immunocompromised?

Wolfe: I’m not sure that mental health has ever come into the direct considerations here only because we would expect their immune system to be just as functional as any one of their age-appropriate peers —  not to say getting COVID or the worry of getting COVID isn’t a real issue. 

This is where we need to make a separation between purely immunosuppressed individuals and the rest of the at-risk group. 

Let’s take Pfizer, for example. There’s two doses in a regular course. When you were vaccinated, however, a few months ago, you would have had a first dose and three weeks later a second dose. There are certain sections of folks who are immunosuppressed, who we know that their defense and their response to that vaccine was not as good as the general community. That is true of people who are at least moderately to highly immunosuppressive — transplant patients, people getting chemotherapy, patients with advanced HIV – there’s a small group, we think about two to three percent of the population fall into that category. They’ve already been independently focused on and they’ve been given three doses in their original course. The way I tend to think about it is someone who’s immune suppressed, their initial course is three doses, not two.

Boosting is a separate sort of group. Boosting is you had a great response originally whether it was to two doses or three, but over time, your defense has faded. 

Let’s think about either the elderly, whose defense fades more rapidly, or people in whom a breakthrough infection would be more critical such that they’re at high risk of a bad outcome. And that includes all the other reasons why people get sick with COVID — obesity, diabetes, heart and lung disease. 

Then there’s a third section, groups of people who are just so repetitively exposed to COVID that their risk of a breakthrough goes up. That includes health care workers, people who live in dormitories, prison workers or inmates.

NCHN: Is mixing and matching vaccines safe? Is there a specific vaccine pairing that’s better or worse?

Wolfe: The question that was always out there was maybe the best defense here for COVID is to stimulate the immune system in a couple of different ways? This was documented both in international trials already, but domestically in the NIH trial, which was that whichever order of vaccines you give, the better responses appeared to be in the group who took the mRNA doses. 

So whilst it’s now allowed and safe and quite effective to really get any boost following any original course, it does appear that the best antibody responses are if you start with an mRNA dose and finish with an mRNA dose. If you are someone who took J&J because maybe you prefer a single jab, it’s very clearly better that your boost be an mRNA dose.

I appreciate the anxiety but I also think it’s worth knowing that there’s been no signal that there’s anything worse or different about the boosters. I’ve cared for a lot of people who’ve died for COVID, I haven’t cared for a single person who’s died because of problems with the vaccine.

NCHN: Probably people are worried if they have the J&J and Thanksgiving is coming up. Should those people be getting a booster?



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