While the CDC initially recommended COVID-19 booster shots for a limited swath of Americans, last week they updated their guidance to allow all adults 18 and up to receive a booster.
Data have pointed to breakthroughs among the earliest vaccine recipients, as well as older individuals and those with pre-existing conditions.
On this week's episode, Katelyn Jetelina, PhD, MPH, an epidemiologist at the University of Texas School of Public Health in Dallas, walks us through what to watch for when it comes to breakthroughs, as more Americans travel this holiday season than since the start of the pandemic.
The following is an abridged transcript of her interview with "Track the Vax" host, Serena Marshall:
Marshall: Dr. Jetelina. Thanks for joining us.
Jetelina: Hi, thanks for having me.
Marshall: So why is it important, before we dive into the data, to understand and know how many people have been hospitalized with COVID despite getting vaccinated?
Jetelina: Where do I start? It's really important for a lot of reasons. I think first and most importantly, for the public, it's transparency. It provides real-world evidence that vaccines are working. We are in a war of misinformation and disinformation right now.
Having this level of data would sure ease scientific communication to the communities that are still hesitant. I think that ... the reason this is important is really for policy making. Who needs a booster? How do we bring the public along for the ride to show them and to have them anticipate when a booster is coming, and not only booster conversations, but really an off-ramp to this pandemic. Are fully vaccinated, is like a room full of fully vaccinated, people safe? What are the off-ramps for this pandemic? We don't know. And that's largely because we are missing a lot of data in the United States.
Marshall: So, why is it important, though, to have that data in real time versus aggregating it, deciphering it, and then reporting it maybe a month or 2 months or 4 months later?
Jetelina: Well, this is a rapidly evolving situation. This pandemic changes every single day. And if we have poor-quality data in real time, we will not be able to make great policy decisions in real time. And so this lag of data is not helpful. It's not helpful when we are moving a thousand miles per hour.
Marshall: So let's dive into the data that we do know. Some states are reporting breakthrough cases. Some are reporting breakthroughs that lead to hospitalization and deaths. So what's it trending?
Jetelina: You're right. Some states are doing a beautiful job at this. Actually, the first person I always look to is the Oregon health authority. They have a breakthrough report every single week. What they do is report cases by vaccination status, as well as the severity of breakthrough cases. And what we're seeing with that is that vaccines continue to work fantastically against many breakthrough cases.
They continue to work amazingly against hospitalization and death. I think the challenge comes from, are they working because people are getting boosted? Are they working because a majority of the vaccinated are a type of vaccine ...? So, for example, Pfizer versus Johnson & Johnson. And that's something that I haven't seen parsed out very well at a state level, either.
Marshall: So, Oregon's doing it right. Are there others that are doing it right?
Jetelina: There are, and I think ...I can't give you a list of them.
Marshall: Yeah, we're not going to go through all 50 states.
Jetelina: But yeah, there are a lot of people doing amazing work. The problem is that we really need a national view because someone, you know, a situation in Oregon doesn't necessarily mean it's the same situation, for example, in Texas, where I am. Or in New York that was hit hard in the beginning of the pandemic. And so an ability to parse out all of this data from a national level is critical.
Marshall: Do you think that as we head into the holiday season, we're going to see an uptick in breakthrough infections or is that part of the problem that we just don't know because we don't have any data to look at?
Jetelina: Yeah, we don't know. What we do know is what's happening in Europe, for example, this month, mid November, is that cases are exponentially increasing. And the challenge is that they have higher vaccination rates than the United States. Europe has acted as an early warning signal for the United States.
When we start looking at European data, what we're seeing is those countries that have the highest vaccination rates are actually doing very well right now compared to the countries that have lower vaccination rates. The other problem we're seeing in Europe right now is -- and I think you mentioned this in your beginning segment in the intro -- was that there are vaccinated people heading to the hospital. Specifically, for example, in Germany. We're seeing quite a few people end up at the hospital who are vaccinated, and this is because they haven't had their booster shot. Only 4% of Germany's population was boosted. So going into holidays from the United States perspective, we, as epidemiologists, are pretty nervous of what this may look like.
Marshall: Now, you just mentioned the booster shots. And you mentioned that earlier, as well ... having the data would help us determine who needs boosters. The CDC, though, had released pretty broad recommendations for boosters and kind of left it open to individuals to decide. So what does that mean?
Jetelina: They did. They left it broad, and so we need everyone as fully protected going into this winter, especially our high-risk individuals: the elderly, those in long-term living facilities, those that are immunocompromised, etc.
Marshall: So those individuals are the ones at highest risk for a breakthrough. Who else would be at highest risk?
Jetelina: Those are the highest risk. Also we're seeing if you have a medical comorbidity, you're at higher risk for a breakthrough case. And then we think -- although, again, we don't have the data -- those that are exposed at high rates. And so we're talking about in their job. So healthcare workers, those in prison systems, those that are exposed to high levels of virus a lot may be at increased risk for a breakthrough case as well.
Marshall: Do we know if type of vaccine does matter for those that have breakthrough cases and end up hospitalized?
Jetelina: Do we know? So we have piecemeal information. And the last data that I saw was during the booster FDA meeting, which was in September, I think, and what we saw was that there is waning immunity for all of the vaccines, but the rate in which the immunity wanes is much higher for those that had Johnson & Johnson compared to the mRNA vaccines.
Marshall: And so how long after the vaccine is the optimal time to get the booster if you want to prevent a breakthrough infection?
Jetelina: So the current guidance is 6 months after the mRNA vaccine, and for the Johnson & Johnson shot, it's 2 months after the original vaccine.
Marshall: It doesn't really sound like a booster. That sounds kind of more like just the second dose.
Jetelina: Right. And that's a huge conversation because it is, it is a second dose. And Johnson & Johnson are really shying away from calling it a second dose. They don't want to include it as the primary series because then it loses its appeal, right? Everyone liked the idea of one shot.
Marshall: One and done.
Jetelina: One and done, and that's just not the case. And so they have a little conflict of interest in this as well, and a PR problem going forward.
Marshall: If breakthrough infections are accounting for roughly 20% of hospitalizations from the states that we can see the data on, does that mean that it's not really even a booster that's needed, but the booster is actually a third shot and that that's how we should really be thinking of it?
Jetelina: Yeah, it's a really good question. And we don't know because we don't have the data. I think eventually once the transmission calms down, we'll have a much clearer idea on what the primary series should look like for all vaccines. But right now, we're really working in a reactive approach, rather than proactive.
Right now the definition of a fully vaccinated person is two doses for the mRNA shot, and one dose for Johnson & Johnson. So, for example, with mandates, they don't need boosters to be counted as fully vaccinated.
Marshall: Oh, that would make a big difference. Yes. And so if you are fully vaccinated and maybe have your booster, maybe not, what would you be looking for to know if "okay, I do have a COVID breakthrough case."
Jetelina: Oh, that's hard because it can be very subtle. And we're talking, like, having the sniffles. So it's very, very difficult.
You know, some people do get moderate symptoms, like losing smell. My brother-in-law, for example, had to start checking his oxygen levels for his breakthrough case because he got a pretty moderate disease.
But the majority will be very ... like sniffles. We're going into winter and we're talking about the flu and common cold. It's going to be very difficult for people to differentiate between the two, unless people have, for example, at-home antigen testing that they're doing on a regular basis.
Marshall: That's something everyone's going to now stock up on, I guess, to find out if it's a cold.
Jetelina: Yeah, I hope. Yeah. I was just going to say, I hope so. The problem is, it's very low stock. It's incredibly difficult to find antigen testing. And if they are in stock, they're expensive for the vast majority of the population, you know, $25 for two tests that'll get you through 1 week. So we really need to find a national solution to this testing issue as well.
Marshall: Is this whole issue with breakthrough infections and tracking them and boosters really a problem of the CDC or state health departments? Because the CDC can't give us a national picture if the state departments aren't reporting it. And is that where ultimately the solution lies?
Jetelina: Yeah, I'm not entirely, well, I'm not sure where currently the break in communication happens. What I will say is that I'm not surprised. We have an incredibly fragmented public health and even healthcare infrastructure in the United States. So instead of having, for example, one system, like you said, we have 50, and we don't even have 50. We have hundreds within each state from the individual health departments.
So we don't have 1) a reliable way that people are reporting, and then 2) there may be bias in case reporting as well. And so we, again, just don't have a great generalizable view of what's happening.
Marshall: So the CDC did say in May, though, that they wouldn't be tracking all breakthrough cases, just those that result in hospitalization and death. And we know at the time a lot of researchers were unhappy with that decision because it seems like something the CDC should do, is tracking all of them. Explain for us why just knowing hospitalizations and deaths doesn't help with the big picture.
Jetelina: Yeah, I was one of them, or I am one of them, that were very frustrated they weren't going to track that back in May. I think that it's really important that, even if these vaccines work incredibly well, we know those breakthrough rates. One reason is to look at mutations. How well are our vaccines holding up, even if it's mild disease, against how this virus is changing.
I think that also it's important to know that, well, Dr. Leana Wen, she gave a fantastic analogy: vaccines are like umbrellas. They protect very well against rain, but an umbrella during a hurricane, it won't help much. And so if we have another massive wave, like we had with Delta, in the winter months, we need to see how well our vaccines are holding up. Even if [cases are] mild.
The other issue is that breakthrough cases can transmit the virus. So it's not like, you know, you have a mild breakthrough case and you're good and you'll have no threat on the overall community. They can transmit the virus as high as unvaccinated, at least in the first few days of the breakthrough case. And so I think altogether those reasons are incredibly important, as well as inform policy.
Marshall: Dr. Jetelina, I want to come back to what you just said about transmitting the virus with a breakthrough case. A lot of parents are just starting to get their kids vaccinated, still no vaccines for those under the age of 5. So what does that mean for families and those around small children?
Jetelina: It means that we're still in this game. I have two girls under 2. So I completely hear the frustration for families with these young ones. It feels like the rest of the world is moving on when you're still stuck in this thing. I think that what it means is that, as families, we still need to be vigilant.
Our vaccines work fantastically, but they're not perfect. And there is a small chance, it is small, that you could bring the virus back home to your unvaccinated kids. And so what that means is that we have to continue to wear masks indoors. We have to continue to track the county levels of transmission and help it inform behaviors on the ground.
And I think it also means, like I said earlier, if we can afford it as families to do rapid at-home antigen tests ... if you go travel for business, before you come back, run an antigen test, just to make sure you're not bringing it home.
Marshall: Is the time, though, for the virus to sort of take hold the same, that 3- to 7-day period?
Jetelina: For breakthrough cases?
Marshall: Yes, for breakthrough cases.
Jetelina: Yeah. So it looks like, at least with Delta, you're going to be asymptomatic for about 24 hours with a breakthrough case. If you start showing symptoms, then that's 24 hours after your exposure. But, importantly, with vaccines, you are able to clear the virus faster. So the vaccinated are contagious for far fewer days than the unvaccinated. And we're talking about contagious for about 3 to 6 days compared to unvaccinated, which is contagious for about 13 to 18 days with Delta.
Marshall: That's a big difference.
Jetelina: Oh, it's a huge difference. And so yeah, you're still contagious with the breakthrough case, but you are transmitting far less virus than the unvaccinated. And I think that's an important piece of information that many people are missing.
Marshall: What about -- I don't even know if it's called a breakthrough case. Maybe it's just called re-infection? Someone who's had COVID and they think, "I don't need the vaccine because I have antibodies," but then get COVID again.
Jetelina: Yeah, a lot of people are in this spot. And I think really driving where we are with vaccine hesitancy. So, it's true. If you're unvaccinated and you survive COVID-19 disease, you will probably mount an immune response, which means you'll prevent infection and thus prevent transmission. The problem we have right now is that this response isn't guaranteed.
So, for example, people with asymptomatic or mild disease may not mount a strong enough response than people who, for example, survive severe infection. If people do mount a response for infection-induced immunity, we don't know how long it will last. It looks like it lasts for at least 90 days.
Some mathematical models show that it'll be a maximum of 5 years, but on average people mount immunity against SARS-CoV-2 for about 16 months. And so because of this variability, both will you mount a response and for how long, we're seeing re-infection rates much higher among the unvaccinated.
Two peer-reviewed studies in the past few months showed that re-infection rates are about 2.5 to five times higher among infection-induced immunity compared to vaccine-induced immunity. And so our vaccines are continuing to mount a very uniform response across our population.
Marshall: Yeah, a big difference there. And so what about, one of the big concerns is long COVID, and so if you have a breakthrough infection, can you still develop long COVID, since your immunity, your immune response launches faster, you're contagious for a shorter amount of time. Is that still a concern?
Jetelina: Yeah, that's certainly ... I will say our hypothesis is that long COVID is reduced. Unfortunately, long COVID is incredibly difficult to measure [and] operationalize in research studies. So, to my knowledge, we've only had about two studies thus far, and they are fantastic studies, but what they looked at was the rate of long COVID among vaccinated breakthrough cases and they do still happen.
Remember that breakthrough cases are very rare, but among those, about 20% have symptoms that last longer than 6 weeks, which means they have long COVID. These symptoms are the same, includes loss of smell, cough, fatigue, weakness, difficulty breathing, muscle pain, etc. And so unfortunately it does happen. Thankfully it will be rare because breakthrough cases are relatively rare, but it's still a possibility.
Marshall: Okay. So, bottom line, Dr. Jetelina, what is the rate of breakthrough infections? Do we know that number? I know at one point the CDC was saying it was, you know, 0.01%, but since we're seeing up to 20% of hospitalizations among vaccinated in some of these states, do we have new data on what that rate is?
Jetelina: So overall, take vaccines out of it, so, you know, pre vaccines, the rate of long COVID was about 30% among adults. It's ... much lower for kids, which is fantastic. It's about 7% to 8% among kids. Now, when you start taking vaccines into account, 20% of breakthrough cases get long COVID. So if we crunch the numbers, it's about a 0.5% chance of long COVID among the vaccinated.
Marshall: Oh, so what is the chance, though, of just developing COVID and a breakthrough case now?
Jetelina: Oh, developing COVID, I don't know.
Marshall: Do we know what the breakthrough rate is? Like, percentage wise? Do we have any idea?
Jetelina: We don't have an idea on it on a national level. We don't have that data.
Marshall: That's crazy.
Jetelina: Yeah. Yeah, exactly. And that's the problem.
Marshall: So when we used to hear the CDC say 0.01% of cases were breakthrough, where were they getting that number?
Jetelina: They were probably looking at it retrospectively. And the challenge is when we look at it retrospectively ... that's not the situation right now. For example, breakthrough cases are going to happen a lot more frequently when in the middle of a surge like Delta, just because there's just that much more transmission, that much more opportunity for a breakthrough case.
It's going to decrease when we're at our all-time low, like we saw in June and July of last summer. So, currently, we're like mid Delta right now. We're increasing in cases. I have no idea what the breakthrough case rate right now is.
Marshall: Okay. So we're heading into the holiday season. People are trying to return to a new normal. What will increase your risk of a breakthrough? What should people be cautious of? Is it still safe if you're vaccinated to go see your friends, family, travel?
Jetelina: Yeah, I think it is. Vaccination is the biggest protection that you can ask for it. It does fantastic. Now that doesn't mean that there's no risk, but there's "no risk" in anything. And so if you have a fully vaccinated family, I'm talking fully vaccinated, I am perfectly fine with no restrictions.
We can start trusting our vaccines. Now if you have partially vaccinated, like those for 5- to 11-year-olds, I would still be a little cautious, because partial vaccination is certainly not as efficacious as full vaccination. And then, of course, if you're like me, the reality is you still have unvaccinated people in your family who may be at the holiday party.
And so we need to have a layered approach in that sense, so we both avoid breakthrough cases, for example, for myself, but also to protect our larger community from higher levels of transmission.
Before our Thanksgiving, before our Christmas holiday, everyone's getting a rapid antigen test. They're not perfect tests, but they certainly are better than us doing nothing. So I certainly hope that people can start leveraging these in a way to make our holidays as safe as they can be.
Marshall: It's such a fascinating conversation and something we're going to keep watching. Hopefully, Dr. Jetelina, that data will eventually trickle down.
Jetelina: I think it will. I think it'll always be lagged, but I hope that the CDC hears the pressure. I'm sure they do and continue to update their breakthrough case information.
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