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COVID-19 Update 9/1: CDC on Boosters, Natural Immunity vs. Vaccines, and More

September 1st, 2021 | 20 min. read

By Steve E. Bishop, M.D.

COVID-19 Update 9/1: CDC Meeting on Boosters, Natural Immunity vs. Vaccines, and More

On this week's COVID-19 update, Dr. Bishop discussed the CDC's ACIP meeting on boosters and offered several takeaways based on the meeting. He also answered questions on traveling overseas, long-haul symptoms, getting vaccinated, natural immunity, and more.

Watch the update below or read on for the full recap. 

Analyzing the CDC's ACIP Meeting on Boosters

What I want to do as the main topic today is actually walk everybody through and discuss some of the findings from what's called the ACIP meeting or the Advisory Committee on Immunization Practices.

This is a committee that's essentially part of the CDC and they are the ones that review and formally recommend or not recommend changes in vaccines for the general U.S. population.

They're the ones who have approved the rollouts of Pfizer, Moderna, Johnson & Johnson, and all that over the last nine months here.

They took up this week, on the 30th, the discussion of booster shots and the discussion of whether to put forward an official recommendation for the fully approved Pfizer vaccine for folks 16 and up.

We'll take the first piece first. If you want to follow along, this is their slide deck with all their data.

There are 53 slides in there, so we're not going to go through everything during this time, but I want to bring your attention to a few important items in there that I think are going to be really critical for you guys to take a look at and to understand kind of what's going on with all this.

Takeaway No. 1: Endorsed full approval of Pfizer for people 16 and up. 

The easy thing: they recommended that U.S. people continue to use the fully approved Pfizer vaccine age 16 and up, and I support that recommendation. I think that was the thing to do. I know there's been a little bit of controversy in some circles about the way that the FDA approved the Pfizer vaccine because they approved it under this brand name, comirnaty, which I'm not sure I totally said that correctly, but I'm pretty sure that's roughly what it is.

It's the same vaccine as the one they have been using. The reason they approved it under the brand name and kept using the EUA at the same time was that we're just waiting on production to catch up.

We had to do that so that we can keep using what we've got already while they start producing the brand-name version of the Pfizer vaccine. There's nothing nefarious going on there.

This is just a procedural tactic so that we can keep using all the Pfizer doses that we've already produced. There's nothing concerning with that that I can find. It's the same vaccines, the same components, everything is the same as under the EUA. There's no mystery there. There's nothing strange going on with that. Just want to address that and put that to rest. It's been kind of floating out there here and there.

So let's get into the rest of what happened with the ACIP meeting. Basically, what they wanted to break down were some key decisions.

Takeaway No. 2: No formal decision on boosters for the general population yet. 

And I'll just skip to the sort of a spoiler alert is they did not make any formal decisions on booster shots for the general population at this time because they said they want more data.

I think that that's the right decision based on what we have so far. What they really wanted to know is — do we need booster shots at all for most people? And if we do, do they work, and does it matter?

They went through quite a lot of discussion about this. There's a lot of data if you want to peruse all the data slides. If you're following along, slide 13 is where they start looking at the question of boosters, because there's been this concern that the effectiveness of the vaccines has been waning, in particular for infection. That's a transmission, infection, getting a mild illness, or even asymptomatic illness.

It has appeared that the effectiveness of the vaccines has been declining over the course of the summer. Now they essentially said, "we can't tell if that's because of the introduction to the Delta variant or if that's just because of the passage of time and the immune system waning down."

I think it's probably a little bit of both. What we're going to see with all of these injectable vaccines is that they probably are not — this is me talking, not ACIP — this is me saying we're probably not going to see persistent transmission prevention from injectable vaccines.

We've talked about this a little bit in prior weeks, but injectable vaccines produce good systemic immunity, and that's why you're seeing strong prevention of hospitalization, prevention of death, and severe disease because all that happens internally to the body, all those inflammatory processes.

The antibodies are good at attacking and preventing the virus from doing its damage once the virus is already in the body, but it's probably not going to prevent transmission too much or infection as well over time because the antibody types that we need to prevent transmission are a different kind.

Injectable antibodies primarily produce something called IgG antibodies. Those are bloodborne antibodies and what we need to prevent transmission, to protect the mucosal surfaces, is something called IgA antibodies. Injectable vaccines do not stimulate strong IgA production.

Now, intranasal vaccines or oral vaccines do that. There is some early, early work going on with mice models on intra-nasal vaccines for COVID, but we're nowhere near having an intranasal vaccine for COVID for humans.

If you guys remember back, we had FluMist a number of years ago for the flu, and it was the same theory, right? That an intra-nasal vaccine was going to do a better job of producing immunity and reducing transmission of the flu.

In that case, they were using live virus. There were some issues with that. And so that ended up actually getting taken off the market. The ones that I've been seeing tested so far are all inactivated sub-components for COVID. So I think they'll go a different route if they go that direction.

Takeaway No. 3: There is some declining effectiveness in terms of transmission, but still strong protection against severe disease. 

But you've seen the effectiveness of the COVID vaccine in terms of transmission start to wane. And I think that's because again, you're not seeing a robust IgA antibody response with these intramuscular vaccines, but you're still seeing good strong protection against severe disease.

And that's really what the data from ACIP is showing and what they're presenting here. If you're following along in the presentation, like slide 13, they show, yes, there's a modest decline in the effectiveness of the vaccines in terms of hospitalization, but it's still very, very effective — 80% or more in most cases.

But you look down to slide 14 and that's where you look at infection, right? And that's dropping off down into the 40% range for Pfizer, a little bit better for Moderna, but that is dropping off.

Again, I think that that's kind of expected, based on the mechanism of the vaccine. I think that makes perfect sense to me why that would happen.

So the question really becomes, it's sort of two questions, and this is what I think they're grappling with — A) Would a booster shot actually fix this problem? Would one more intramuscular injection produce more than enough what's called neutralizing antibodies and IgG antibodies to really tamp down the infection risk?

Essentially produce so much of a response that it doesn't matter we're not getting a good IgA response and that will still keep the infection risk down.

So that's sort of one question. And then B) What's our goal here? Is our goal really to prevent infections or is our goal to keep people out of the hospital and keep them from dying?

And those two things really need to be balanced. And based on what I'm looking at here, I think that ACIP is really leaning toward this question of saying, we may not get to a point — and this is me sort of reading between the lines interpreting their data — we may not get to a point where we can consistently prevent infection, especially mild infection, asymptomatic infection, but we probably can get to a point where we can prevent most of the hospitalizations and most of the deaths, and I think that's where they're leaning toward.

If you look down to slide 17, you'll see a continued robust response and robust protection from symptomatic infection, from hospitalization, and from severe disease up in the upper 90s, almost 100% for severe disease and hospitalization for both alpha variant and Delta variant.

And symptomatic infection prevention is still in the 80-something-percent range across a number of studies. And you can see this also on slide 18, yes, you have some decline, right? A little bit of decline from the 90s to the 80s or so for the Delta variant, but that's still exceptional protection from hospitalization and death, even with Delta variant, from the first two doses of vaccine.

If you look on the left of that slide, they do show a pretty significant decline in protection from infection or any symptomatic disease. Now that could be somebody with a stuffy nose, right? So you do have a decline against that, and I think, again, that's consistent with the mechanism of the vaccine.

I think if you keep going down again, slide 19 kind of shows the same thing, prevention of severe disease and hospitalization for all the vaccines remains very high, which is good.

Takeaway No. 4: They are looking at recommending boosters for certain subgroups, such as older adults and long-term care residents. 

They do show — if you move down to slides 21 and, in particular 23 — for adults age 65 and up, they wanted to start looking at subgroups.

And they said, "okay, that's the overall... are there certain groups where the protection from hospitalization in severe disease is waning more than others?"

They broke it down and what it looks like they really found is that the protection remains high except for those 75 and up, and also those who live in long-term care facilities. The protection from the first two doses was never amazing. It was good but not as good as we would want in the 70% range. And that has stayed kind of low in that realm. Protection from infection has been again, kind of in that same lowish category.

Takeaway No. 5: The first booster recommendation is probably going to be for older adults, long-term care residents, and maybe healthcare workers. 

I think what we are going to wind up with, based on all this data, and this is kind of what ACIP was getting to. If you go down to their sort of final summaries on slide 39, they basically are saying vaccines continue to maintain high protection against severe disease for almost everybody.

But they're basically looking at in slides 40-41 whether certain subgroups like the over-75 crowd and the folks who are living in long-term care facilities will need boosters, but for the express purpose of reducing hospitalization and death, not so much for preventing infection.

And I think that that, for me, based on everything I've read the last year and a half, my medical knowledge, everything, I think that's really where we're probably heading.

I know there's been some controversy in the news this week about some disagreements between CDC, ACIP, FDA, and the president's team on the virus about this issue. But again, I think that really what the data is showing us is that the vaccines continue to be very, very effective at keeping them out of the hospital, even all these months out, with the exception perhaps of the very elderly and those who are very at-risk from living in nursing homes, long-term care facilities, things like that.

Probably, my guess, is you'll see the recommendation come out for boosters for those people, maybe for healthcare workers, based on a little bit of data that's in there that you can peruse. But I think we may not see a booster recommendation for the general population right now.

We may see one eventually if the signal and the data changes, and we start to see significant upticks in hospitalization and fatalities or for vaccinated people. So far, those are staying very low. They're not zero, of course, right? The vaccines are not perfect, but they're staying very, very low.

I know a lot of people are worried about breakthrough infections, and it certainly is happening, but it is still very rare with a vaccinated person, and even more rare for a vaccinated person to be in the hospital, and even rarer than that for a vaccinated person to die from COVID.

Takeaway No. 6: The long-term goal will probably shift to "let's make this as much of a non-event for people as possible." We will probably not completely eradicate COVID from the planet. 

I find this to be very good, encouraging news from ACIP. I think this data is a glimmer of hope that we hopefully will not be stuck dealing with a persistent problem where our vaccines stop working all the time in terms of preventing severe illness, just because we have variants popping up.

But I think it does lend credence to the idea that this is most likely going to become an endemic infection that we're not going to be able to completely eradicate off of the planet anytime soon and perhaps never.

But the goal probably is going to have to shift to "let's make this as much of a non-event for people as possible." Let's turn this into a common cold for everybody, and that's where the vaccines are really going to do their job.

I think that's where ACPP is headed. Again, a little bit of reading between the lines, but based on the data and the phrasings of their sort of recommendations from yesterday, I think that's where they're headed.

And again, if you look at slide 41, they have it in bold and red letters, they say the top priority is continued vaccination of unvaccinated people.

They view booster vaccines, the first priority they said is the prevention of severe disease in at-risk people. So again, that's that 75 and up and long-term care.

And they did not — it's several layers down — they are sort of thinking, "okay, maybe then we'll start talking about and worrying about booster doses." So I think we may not have booster recommendations for most folks out there.

Traveling Overseas

"Over 90% of adults in Ireland are now fully vaccinated. Would you feel comfortable traveling overseas now? I have five grandchildren — ages eight, eight, seven, six, and three. How long before vaccines are ready for younger children?"

Yeah, as a vaccinated person, I would feel comfortable traveling overseas for sure. I know the EU, I heard yesterday or the day before, they were actually going to change some of the travel rules for U.S residents, so that may impact things.

But other than that, I would feel comfortable going and traveling overseas as a vaccinated person. I wouldn't be overly worried about that, but the local government rules have perhaps changed, so maybe check into that a little bit more before you go.

And then how long before vaccines are ready for younger children? I don't know the answer to that. My guess is not before the turn of the year. I think it's going to be a little while. Last I heard they were still gathering data and were still trying to finish the trials, so I think we're not going to know that for longer.

When it comes to the younger kids, because the disease tends to be less severe in general, you have to have pretty big numbers of participants in the trials to find what you're looking for. It's just the way the math works out, because the outcome you're looking for is a rare outcome to start with, and you're trying to make a rare outcome even rarer with a vaccine.

So you have to look at large numbers of people. And so my guess is they're still trying to get the numbers to present the trial data. And so I don't think it's going to be anytime in the next few months.

Long Haul Symptoms

"No one wants COVID, especially with the risk of long haul."

For sure, absolutely. Now what I'll say though. I think that vaccines, what you're going to find is that they are going to prevent the long-haul symptoms for most people. Even if you get a breakthrough infection, I think you're probably unlikely to have long-haul symptoms, because I think most of the long-haul symptoms are reflective of that internal systemic inflammation that happens from the severe infections.

And with the vaccine, you're not really having that happen. So I think you'll see that the vaccines will keep those long-haul symptoms from occurring because you're not going to get that sick.

Length of Immunity from Boosters

"I got all three Moderna shots. How long will that last?"

Hopefully a really long time. We've got data from before that the response rates weren't always the best in immunocompromised people, etc. So I think that their recommendations on the older crowd, immunocompromised people, people who have high-risk, long-term care, nursing home, all that, that's a good population to get the boosters and probably will last a good long time.

We're not going to know probably for another six to 12 months if we're going to need further vaccination for those high-risk groups. Sometimes it just takes a few doses.

There are many vaccines, and they talk about this in their slides, there are many vaccines that require a multi-dosing strategy that have been around for decades.

Hepatitis B, hepatitis A, polio, all these things, MMR. They require multiple doses over long periods of time in order to maintain lasting immunity. We may find that it's like that for this one too, especially for high-risk people. We may find that that's necessary, but we're just not going to know for a while yet. 

Other Vaccines? 

"Are other types of vaccines being worked on other than three we hear about?"

Yes, there are other ones out there. There's one called Novavax. That's not approved in the U.S. There's still AstraZeneca. That's not approved in the U.S.

And then there are some early, early studies on — we talked about this a few minutes ago just briefly — on mice models of intranasal vaccines.

So there are many other things being worked on. They're just not as near to completion in the pipeline as these other things.

And honestly, the ones we have worked pretty well, and we've got experience using them now in hundreds of millions of people. So there's a lot of confidence with continuing on with that product rather than shifting to something new that's not as well tested.

Moderna Antibodies > Pfizer Antibodies? 

"A study showed that Moderna produces more antibodies than Pfizer. Are you familiar with it?"

Yeah, so yeah, there is data out there showing that the Moderna, and this is in the ACIP data that we just went through, if you go through and look at their charts, the Moderna vaccine does in general perform a little bit better than the Pfizer vaccine.

It's not a game-changer for most people, but it does perform a little bit better for the most part in terms of protection levels, so that is true.

That being said, whichever vaccine you want to choose, it's going to work fine for you. If you want to pick between, and you want that little bit of extra protection, I think choosing Moderna is fine. The Moderna is primarily what we've been offering our patients here at PartnerMD for two reasons. One, Moderna is easier to give — it's easier to maintain it, doesn't have to stay as cold, you can mix it up easier. It's just simpler to give, and the protection is slightly more effective.

Future Variants More Transmissible?

"It seems like with each variant, the main difference is that they are more and more transmissible. Is it likely at that's the main difference going forward, and we'll just keep getting progressively more transmissible?"

Hard to say, honestly. I don't know what's going to happen with that, but they will probably at least stay as transmissible as it currently is. But there's no way to tell. The evolutionary mechanisms here are random to a certain degree, but they're always going to try to find a way to escape the vaccine control in terms of transmission.

Remember the goal of a virus, if a virus can have a goal, is to replicate itself. It's always going to try to find a way to replicate itself.

An ideal virus is one that replicates rapidly, freely, but does minimal harm to the host, because it can replicate a lot without killing the host, without damaging the host too much, and continue to be passed on to the next person. So, yeah, I suspect we'll continue to see more and more of the same.


"A while back, you shared a study that you had masks were not proven to be effective. What is the latest science on masks?"

Yeah, that continues to be a really controversial topic. And I think the latest data from update number six from the Annals of Internal Medicine continue to basically say we need more information about this in community settings.

Clearly, they are very helpful in the healthcare setting. Out in community settings, it remains a little bit more questionable.

There was a study that came out recently as well, looking at the data of masks in schools in particular, and they did show there that there was a reduction in transmission when the teachers were wearing masks, which I thought was really interesting, but not when the students were wearing masks too much.

Who knows why that may be, perhaps it's because the teachers can wear them properly and they're not still touching their face stuff all day long, whereas the kids are still taking their masks down. They're not wearing them right. They're touching their face, whatever, but that was an interesting study.

So again, when the teachers wear them, there was less transmission. I think that's really consistent with the data we have seen out of schools in the prior year and a half, which is that most of the transmission that happens in schools is actually between the adults, not so much between the kids or between the kids and the adults, but the adults to one another, so one teacher to the other. I think that's interesting in that new mask data does kind of jive with that as well.

I think the problem is it's just really hard to do these studies, to prove this or disprove it one way or another. I think we're still kind of stuck in this limbo land where the data is not strong for masks in the community setting.

And you know, it hasn't been definitively disproven, but it hasn't been definitively proven as effective either. And I think we just have to be honest about what the data is telling us at this point with the mask thing.

But that was an interesting new data set that did come out in terms of showing that masking the teachers did seem to reduce infection risk for folks in the schools. So I thought that was interesting.

Next Variant?

"What is the next variant and the status of it? It feels like we heard about Delta long before it got here, and it's still the main variant talk about, but also it might've peaked. I'm wondering what's next and what we know about it?"

Yeah, there are actually several going on. There's a Delta plus. There's Lambda. I heard today there's Mu and there will be others. There are a couple of other ones that are out there but haven't received a Greek-letter designation yet.

We're going to continue to see these. They're not going to stop developing over time. And again, this is really consistent with viral replication in general. Most viruses mutate over time. The flu does this. HIV does this. Pretty much every type of virus does this. So we're going to keep seeing this happen with COVID most likely.

The real key is going to be making sure, again, that none of the variants escape control from the vaccine in terms of severe illness and hospitalization.

As long as those IgG antibodies from the vaccine continue to work against all these variants, then I think that's great. That's a win. But as they pop up, we'll have to keep testing them. It's going to be something the vaccine community is going to have to stay vigilant with over time.

But I think in general, I wouldn't get too alarmed about each variant as it pops up, and if one does pop up that is showing escape from the vaccines, I think we've proven that the technology for creating these vaccines works pretty well, and we can always create a new one with the protection against any of the ones that do escape the current vaccine.

Thoughts on Vaccinating a 12-Year-Old

"Would you be kind enough to share your thoughts on vaccinating my 12-year-old daughter?"

Yeah, great question. I think that that is very much an individual decision based on what you think your daughter's risk level is for COVID and for the vaccine.

If she's really healthy, I think it's a reasonable option if you want to wait. I think that's okay.

It's also very reasonable to go ahead and get vaccinated. The vaccines are safe. I don't think there's any reason not to give them at this point.

We're coming up on the year mark of the data. I think in a couple more months, we'll have a year's worth of data on the 12 and ups. So we're going to get more comfortable with that. We've given lots of doses to 12 and ups at this point, so I think either choice is very reasonable.

Now, if your daughter has underlying medical problems, that would lead me towards saying, get the vaccine.

If you have questions, you're not sure, just chat with your pediatrician about it. And they'll be happy to give you guidance one way or the other.

I think that that, again, either choice is a fine choice, and if she's got medical problems, I would lean toward getting the vaccine sooner rather than later.

And what I'd say is, when I say either choice is a fine choice, what I mean is waiting a little longer to get the COVID vaccine. I don't mean never getting it, right?

So if you want it to wait a few more months for more data and to make sure the safety signals are good, I think that's a fine choice. I wouldn't necessarily say delay indefinitely.

Children Traveling Overseas

"Do you feel like it's safe for children to travel overseas since most have not been vaccinated?"

That's an individual family decision to take again in terms of risk tolerance. Data continues to show that the vast majority of kids do perfectly fine with COVID and have minimal symptoms.

My daughter had COVID recently and did fine with it. She had a fever for a few hours and a sore throat for a day, and then completely recovered. That's an anecdote, but that's consistent with what the data has shown over time.

So if you are comfortable with that risk level, I think it's fine to travel. If you want to wait until the kids get vaccinated, I think that's fine too. You just have to decide what you're comfortable with as a family, in terms of that risk.

Natural Immunity vs. Vaccines

"Do you subscribe to the news that natural immunity from having COVID is as good or better than a vaccine?"

What I'd say is it's not really a view — the data does show us that natural, sort of, protection from natural infection is probably equivalent to vaccination. I think that's fairly clear from the data.

But also clear from the data is that recovered people who get vaccinated have even more protection than just the recovered.

I think that both things are true. And I think that's why you've continued to see the recommendation come out of CDC to say, even if you've recovered at some point, you really should consider getting vaccinated, mostly because we don't know how long that immunity will last.

And I do think there's an unanswered question of, okay, if you had a really mild case, all you had was a stuffy nose and maybe a sore throat, is that really enough to prime the immune system to protect you over the long-term? And I think that question is still unanswered.

That's why I think if you've had COVID and you had a mild illness, I think that that really probably you should get vaccinated after you've recovered.

If you've recovered from a severe bout of COVID and you were super sick, you could probably wait.

It's a nuanced issue, but natural immunity works. The immune system does function. The real problem with this whole idea. Everybody's very focused on natural immunity and that's fine. We should include it as part of the way we make recommendations.

The problem is you can only get natural immunity if you survive the first time, right? So if you get the disease and you don't survive the first time, it doesn't really matter if the natural immunity works to prevent a secondary infection.

So that's the risk you're taking, right? So yes, natural immunity functions, but again, you've got to live through it the first time. And that's the thing.

You can have natural immunity to all kinds of viruses — smallpox, polio, whatever. But you have to live through it the first time. And that's the crux, right? That's why the recommendation remains everybody get vaccinated at least one time.

More Positive Cases = More Herd Immunity?

"As more positive cases are happening every day, does that add to the number of immunity, herd immunity? Could it be a further discouragement of those not wanting to get vaccinated?"

Yeah, I think it probably is adding to this herd immunity concept number of people, you know, I think the problem is we still just got a long way to go. A lot of people, thankfully, still haven't been exposed. But yeah, as people acquire natural infection and recover, that will add to the herd immunity.

the problem is, like I just said, that the older you are, the sicker you are, the more you're rolling sort of loaded dice in terms of banking on that natural immunity.

You have to live through it the first time to get natural immunity, and that's the big thing, right? What is the whole reason we vaccinated people for anything, right? Because we don't want to take those risks, right?

You don't want to take the risk of getting Hepatitis B or polio or measles or whatever, because there's a significant chance you might die the first time around. And I think that that's true for many people, not everyone, but for many people with COVID as well.

Monitoring Antibodies

"I apologize if you already covered this. Is there a way to see the strength of antibodies that we are carrying, whether it might be from vaccination or previous infection?"

Yes, there is a quantitative antibody test. We don't understand everything about that test at this point, in terms of what level of antibodies is needed to provide long-lasting or even strong protection, but that test is available.

We do use it here from time to time for certain people. But yes, there is a test available, it's called a semi-quantitative antibody test for COVID antibodies.

Testing for Antibodies

"If you had a mild illness, what are your thoughts on getting tested for antibodies?"

Yeah, I think that that could be potentially helpful if it's going to sway you one way or the other in terms of getting a vaccine.

If you've got somebody who thinks they had COVID and maybe they never got tested or maybe they had a super mild illness and they're just not sure about getting vaccinated, I think that's a good person to get antibodies checked.

Because if your antibodies are low, that will provide a good impetus for their doctor to say, "Okay, hey, I know you think you had COVID last year, and I know you had a mild illness and that's great, but you know, because of that, your antibody levels are pretty low, and I don't know if you're going to do as well if you get exposed again."

Unvaccinated and Vaccinated People Living Together

"What are your thoughts for unvaccinated relatives living in the same household with vaccinated people?"

I think that the unvaccinated people are taking a risk doing that, right? Again, depending on their risk level.

If you're talking about a healthy 20-year-old who's unvaccinated living with vaccinated people, I think the risk is pretty low for the 20-year old in terms of a bad outcome.

If you're talking about several 50, 60-year-old people living in the same household and a couple of them are unvaccinated, I think those people are taking a really significant risk in terms of getting and not doing well with COVID.


"Will COVID tests tell you if you've ever had COVID?"

An antibody test will probably indicate if you've ever had COVID. The COVID tests that we do — the antigen test, the PCR test — that's only going to tell you if you're infected with COVID at the present time. It won't tell you if you had COVID month ago. 

When is the next update?

Our next update will be Wednesday, September 8, at 1:00 p.m. live on the PartnerMD Facebook page. As always, we will post the full video and complete blog recap on Thursday morning. 

Steve E. Bishop, M.D.

As a board-certified internist and concierge doctor in Richmond, VA, Dr. Steven Bishop is passionate about helping his patients improve their lives through better health. He helps healthy adults adjust their lifestyles as they age and helps patients with complex medical diseases manage and improve their health.