Take Note: Epidemiologist Dr. Nita Bharti On Safety And Effectiveness Of New COVID-19 Vaccines

Jan 29, 2021

Epidemiologist Dr. Nita Bharti
Credit Nita Bharti

The COVID-19 vaccine is slowly rolling out across the country. Some people still have concerns about these new vaccines and their safety.

We had epidemiologist Nita Bharti answer some of those questions. Dr. Bharti is an Assistant Professor of Biology in the Center for Infectious Disease Dynamics at Penn State. She’s been educating the community about COVID-19 since the beginning of the pandemic. 

TRANSCRIPT: 

Emily Reddy:  
Welcome to Take Note on WPSU, I'm Emily Reddy. The COVID-19 vaccine is slowly rolling out across the country starting with health care workers. Some people still have concerns about these new vaccines and their safety. We have epidemiologist Nita Bharti with us to answer some of those questions. Dr. Bharti is an assistant professor of biology in the Center for Infectious Disease Dynamics at Penn State. She's been educating the community about COVID-19 since the beginning of the pandemic. Dr. Bharti, thanks for talking with us. 

  
Nita Bharti:  
 Thanks for having me, Emily. 
  
Emily Reddy:
 So I asked on social media for questions about the COVID vaccines and I got dozens of questions. This is clearly something people are very interested in. But the question I got the most was, this vaccine was developed really quickly. Is it safe? 
  
Nita Bharti:
 Yeah. And that's a great question, right. So we have not had a vaccine go from a need for it to actually being able to deliver it this quickly. And there's a number of innovations that happened with this vaccine that have made that possible. And one of them was just in the way that it was developed. A lot of the steps that we normally do sequentially happened in parallel for this vaccine. And that meant that there were some extra costs and that a failed vaccine would be expensive. But it meant that a successful vaccine would be available quickly. So that was sort of a cost versus time trade off. All of the steps that are required for safety review and external review of safety and efficacy were conducted as they would be for any vaccine. They just all happened much more quickly, because we did a lot of those steps, like I said, in parallel. So a lot of production of this vaccine was happening before the approval. And that if the approval didn't happen, that meant that those vaccines would have been thrown out. But that was okay, in this case, because there was such a global need for a vaccine.
  
Emily Reddy:
So the Pfizer and Moderna vaccines are mRNA vaccines, what does that mean? 
  
Nita Bharti:  
So it's a really interesting and important new innovation. Most vaccines that we get are like a protein. So some part of the actual pathogen -- that is not dangerous, but is a part of the actual pathogen -- is given to the recipient. In this case of an mRNA vaccine, what's happening is, the instructions to make a part of the pathogen are being given to the recipients, not part of the actual pathogen. And so that does a couple things. It actually sort of puts your body in the driver's seat a little bit more. You're getting the instructions to make this thing and it's not harmful. And you're making it. It also makes it a lot faster to produce those vaccines, because you can produce the mRNA without having to grow up the pathogen and then purify it, and then make the vaccine. 
  
Emily Reddy:  
Are all of the vaccines being developed for COVID-19 going to be mRNA vaccines? 
  
Nita Bharti:  
They're not. So the reason that the first two that were approved were mRNA vaccines has a little bit to do with the fact that mRNA vaccines are faster to produce than traditional types of vaccines. The Operation Warp Speed project has selected eight vaccines to bring into the system of parallel... parallelizing a lot of the steps for vaccine production and assessment. They picked two from every kind of vaccine class or vaccine type. So the two that moved forward the most quickly were the mRNA vaccines. The others are all something else. 
  
Emily Reddy:  
And the Johnson & Johnson one we've heard about. That could be a one shot vaccine. You know, what difference would that make?
  
Nita Bharti:  
There's probably a couple of things that we want to consider. Obviously, a single shot is is better than than a second shot required because you do lose people to attrition. There's no getting around that. Efficacy after a single dose for the two approved mRNA vaccines. I think it's not quite perfectly known yet. We know it's not as high as the numbers for two doses, but it's there's some efficacy. So it kind of depends on what we find the efficacy of the Johnson & Johnson vaccine to be after one dose. 
  
Emily Reddy:  
And the Pfizer and the Moderna are about 94 or 95% efficacy, is what we're seeing. 
  
Nita Bharti:  
 That's right. That's after two doses. Yeah, I mean, the the advantage of a single dose at treatment is huge, right? You don't have to bring people back in. You don't have to worry about one of the things that we are worried about is there might be an issue of with single dose administration for these two dose vaccines, there might be this issue of are we actually priming the virus for vaccine escape? We don't know, right? For "immune escape evolution." 
  
Emily Reddy:  
 What does that mean? 
  
Nita Bharti:  
 So basically means... and to be to be clear, we don't know if this will be an issue, but some people are worried about it... It means that if you have a weakly immunized population, you're sort of showing the virus, what it would need to get around the immunity created by the vaccine, right. And so it can evolve. Not that it's sentient. But the mutations that are that are successful at getting around the vaccine-derived immunity, are going to be more likely to survive and persist and transmit. So if we have a population where immunity is slow to roll out, and we're ending up seeing people with a lot of partial immunity, because of only receiving one dose, there is a chance that we are creating a niche for evolution to sort of take this virus in a direction that escapes the vaccine. We don't know if that's true. It'll be a while before we know if that's true, but that's something that some experts are really worried about. Because you don't bring up a population from no immunity to full vaccine derived immunity overnight There's a process and what that time lag does to allow this virus which evolves very, very quickly, to get around some of this immunity might might cause problems.
  
Emily Reddy:  
 That's interesting. 
  
Nita Bharti:  
 So I think we would worry about that a little bit less with a single dose vaccine. 
  
Emily Reddy:  
 What do we know about the long-term safety of the vaccine? You know, could it cause problems 10 years down the road in someone who gets vaccinated today?
  
Nita Bharti:  
 There's a few things we know about vaccine safety in general. And that sort of has shaped the way that we do our safety trials and assessments. One of the things that's really critical is that most vaccine safety issues arise within 30 to 60 days after receiving the vaccine. And so, obviously, the trials have accounted for all of that. They've done the two months of safety follow up and in all the trial recipients. Very long term vaccine side effects are highly unusual. And so we don't expect that there will be sort of 10 years down the road vaccine side effect that's unfavorable. You know, there's no way to know for sure, because we haven't had the vaccine around for 10 months, but that would be very highly unusual.
  
Emily Reddy:  
 Once people have received both shots, they should be immune from getting sick. But can they still be asymptomatic carriers and get others sick? 
  
Nita Bharti:  
 Yeah, this is a really important point. So a couple things we know about the currently approved vaccines is that they're protecting the recipients from disease and specifically from severe disease. We don't really yet know how much they're protecting individuals from infection and infectiousness. So there is still a chance that people could be getting infected and being able to transmit the virus to others, but they're not going to experience disease from it. 
  
Emily Reddy:  
 So after you're vaccinated, you'll still have to wear a mask, socially distance, not do gatherings, those kinds of things? 
  
Nita Bharti:  
 Yeah, and that's really critical. Certainly, even after individuals are vaccinated but for a while until a lot of people are vaccinated. So until we get our population levels of immunity, or at least population levels of disease protection, up really quite high. 
  
Emily Reddy:  
And will we know at some point whether people who are vaccinated, are able to actually get the disease asymptomatically and pass it on? 
  
Nita Bharti:  
Yeah, certainly, we will know that. And that is something that's in progress now, just understanding that. But we just don't know it yet. And that's not I mean, that's not unusual, it doesn't make the vaccine less safe. So just, for example, the polio vaccine, the oral drops, they work like that. So so if you receive a polio vaccine that is oral drops, the person who receives that vaccine is protected from disease, but they can still get infected and transmit the polio virus. And that is a... it's a successful vaccine. It's not a first, right. So if that were to be the case, it's not like we're in uncharted territory and we don't know what we're doing. That's a thing that happens. It doesn't mean it's not a safe vaccine if that is the case.
  
Emily Reddy:  
Should people who have already had COVID-19 still get vaccinated?
  
Nita Bharti:  
Yeah, it is recommended that people who have already had the disease get vaccinated. And some of that has to do with the fact that we are seeing reinfection. That is a possibility. And some of that just has to do with, you know, immunity does wane and so  it's definitely worth it to get the vaccine. 
  
Emily Reddy:  
Do we know how long this vaccination will last? Is this something that people are going to have to get every year like the flu vaccine? Or is this a one time thing? 
  
Nita Bharti:  
This is a great question. And this is the one that we're getting a lot. There are certainly unknowns regarding how long will this vaccine derived immunity last. So we don't know. The reason that we get vaccines like influenza every year is because influenza evolves. So influenza does immune escape evolution. And that's why we need a new vaccine every year, it's because the virus itself has changed. For immunizations like measles, we need a booster kind of every 10ish years at the most. And that's because that virus -- measles virus -- doesn't change in an immunogenetically important way.  With COVID we don't quite know with with this new virus, if it's going to be changing, if it's going to be evolving seasonally, like like influenza does or if we'll just sort of need long-term, infrequent boosters to keep our our antibodies and our immune system ready. We just don't know what that is going to be like yet. 
  
Emily Reddy:  
There's the UK variant. Do we know if the vaccines that are being developed that are done and that are in the works will work for that one? 
  
Nita Bharti:  
Yeah, this was a scary moment, a little bit, right. So we we didn't really know at first, is this an immune escape variant? Or is this just a variant that is a much more effective transmitter? But it turns out to be a variant that is a much more effective transmitter, but it is not an immune escape variant. So the vaccines, the mRNA vaccines that have been approved, are effective against this variant. So that's good news. It doesn't mean that that will always be the case. And there are a few new variants that are being looked at as potential immune escape variants. So we will just continue to have to monitor these things. 
  
Emily Reddy:  
If you're just joining us, welcome to Take Note, we're talking with epidemiologist Nita Bharti, about the new COVID vaccines. Dr. Bharti is an assistant professor of biology in the Center for Infectious Disease Dynamics at Penn State. What about kids? Neither of the two vaccines that are currently approved are approved yet for children under 16.
  
Nita Bharti:  
Yeah, and that seems like it's a really critical issue for getting kids back to schools, right?
  
Emily Reddy:  
Yeah. 
  
Nita Bharti:  
So the reason that these vaccines are not approved yet, for kids under 16, or 18, depending on which vaccine you're talking about, is just because the trials were not done on kids. The trials were done on adults. And so that's who the vaccine is approved for. Part of the reason that the trial was not done on kids is because especially very young kids have really different immune systems from adults. And so those trials need to be done, obviously, carefully. But they need to be done with a slightly different eye on on what the what the dangers might be or what the safety issues might be. So those are ongoing. They are probably going to take, I think, conservative estimate, say until the end of 2021. There may be an approval that looks a little narrower than 0-16.
  
Emily Reddy:  
Moderna is currently testing on 12 to 17 year olds. 
  
Nita Bharti:  
Yeah, that's right. And that's because under 12, that the immune system is is is really quite different. And it's developing. Very young kids, teenagers, and then adults. That ends up being biologically important. 
  
Emily Reddy:  
Yeah. What about those, you know, the babies? As someone who has a 15 month old, I'm invested in this question. But you know, when when might this vaccine be available to those those youngest kids?
  
Nita Bharti:  
Yeah. There will have to be trials that test in those age groups specifically. To my knowledge, those are not currently being done. That will be, I presume, the next phase of safety testing for the approved vaccines. But the issue of kids below kind of a year, we would wonder about what their maternal immunity looks like, and whether they would actually develop long-term immunity from a vaccine given at an age that is before they have developed their own immunity. So not to be pessimistic, but I would think that those would be kind of the latest approvals if they were to come through. The good news is that if we can get population levels of vaccination up really high, and surround these these little babies with immunized people, then their risk goes down significantly.
  
Emily Reddy:  
That is a question. You know, what is the level that we need to reach that "herd immunity"? 
  
Nita Bharti:  
Yeah, so herd immunity has had a bit of a moment this year. It's been kind of in the spotlight. It's a very old concept in epidemiology. But in having this moment in the spotlight, it's been a little bit misinterpreted. So we'll go through what it means and what that looks like for COVID-19. 
  
Emily Reddy:  
Please.
  
Nita Bharti:  
Herd immunity has been presented as a threshold. So if you're above herd immunity, then you don't have to worry about this pathogen. And if you're below herd immunity then you do. And that's not really the case. Herd immunity is a continuum. And so, what it really means is that if somebody who is susceptible to a pathogen is surrounded by people who are immune against it, then they are indirectly protected by the people around them.  When we talk about population level thresholds for herd immunity, we mean what level of the population has to be immunized or immune to be protective against transmission across the entire population. And that's generally a very high threshold. And that depends on the pathogen. So the more transmissible a pathogen is, the higher that herd immunity threshold would need to be for population level immunity, right? That gradient is always there. So a few immune people are still contributing to herd immunity. It's just not creating a threshold. So for something like -- we talked about measles before -- for somebody measles, that herd immunity threshold is high from 95%. Because measles is one of the most transmissible pathogens that we know of. For something like smallpox, which was eradicated, it is less transmissible. That herd immunity threshold was closer to 80%. And that was part of why we were able to eradicate it. For COVID-19, if we look purely mathematically, we kind of expect it to be somewhere between, I'm going to say, 60 and 75%. Ideally, we'd love to be way above that. 
  
Emily Reddy:  
A Pew Research Center poll found that 42% of Black Americans would consider taking a coronavirus vaccine compared to 61% of white Americans. This distrust might come from past racist health care. Many of us have heard of the Tuskegee syphilis experiments, which ran into the 1970s. There were also fewer Black and Hispanic Americans in clinical trials. So it's less tested in those groups. You know, why should Black Americans and other people of color trust this vaccine? 
  
Nita Bharti:  
Yeah, absolutely. There's a long and ugly history of Black Americans not being treated equally, or fairly, by science, research and medicine in the U.S. You know, we have the story of Henrietta Lacks, we have the story of the Tuskegee experiments. And and like you said, those aren't that long ago. There are still survivors around. The question of how do you rebuild trust. And how do you rebuild trust with a community that has really been wronged by science and medicine, and continues to be, is a tough one. So we still see higher rates of complications and negative outcomes in childbirth, for Black women than we do for white women in America. And that's a standard of care issue, right? There's no need for that to be the case as the standard of care issue. We know that for Black patients, and particularly Black women, their pain is likely to be underestimated by attending physicians than it is for their white counterparts. So we have a lot of issues with with race and access to equitable health care and access to quality health care. And it makes sense that there is distrust from groups who have been treated badly and have the evidence to say medicine hasn't served me. Science doesn't worry about me.  But the vaccine is safe. It was tested in these groups. There were a high number of total participants. And certainly there were Black and other minority participants in these trials, and the vaccine was safe in in those participants. This vaccine is safe for for all those groups. But I think it really is on the medical community to be rebuilding some of that trust and to be having those conversations really openly, to be communicating about that and to be taking those concerns seriously in in those groups because they're valid. 
  
Emily Reddy:  
And to reach those, I mean, for all of us to reach those immunity thresholds, we're going to need to get everyone on board. 
  
Nita Bharti:  
That's right. Yeah. 
  
Emily Reddy:  
So Pennsylvania just made a lot more people eligible for the vaccine people over 65 people with certain health conditions. A lot of different health conditions cancer, diabetes, obesity, COPD, certain heart conditions, immune deficiencies, sickle cell disease, pregnancy, being a smoker. That's more than three and a half million people in the state. But what's the state's current supply of vaccine like and not enough for all those people? Right? 
  
Nita Bharti:  
Yeah. So we we know, there are supply issues, sort of nationwide. And we know that our that the vaccination levels in Pennsylvania are pretty low right now. Expanding the eligibility does a couple things, it just means that more people will try and go get the vaccine, which is great in the sense that the vaccine that we have, we don't want to waste, right. It has a shelf life. It has these certain logistical constraints, where once it's thawed it can't be refrozen, and it has to be used. So by making more people eligible, there's a hope that more of that vaccine will get used before it cannot be used.
  
Emily Reddy:  
Is it being wasted, currently? Are there shots being tossed because there can't find people to give it to? I feel like I'm hearing stories of that. But I don't know if it's a real thing. 
  
Nita Bharti:  
When you plan a vaccine rollout, that is part of what you plan for. It sounds terrible, but you absolutely need to throw out vaccines that are no longer effective, instead of delivering vaccines that are not effective, right. So if you're carefully monitoring the cold chain, and you're carefully monitoring your vials, there will be some loss. It's not a failure, it's not a success. It's an important part of the process, right? So don't give people vaccines that don't work anymore, whether it's because the whole crate warmed up or because that vial has been thawed for too long. So that on its own is not a problem. But the problem is the scale at which that may or may not be happening. So having a more efficient rollout minimises that and having people with experience in mass vaccinations, in this case helps a lot. And we don't do a lot of mass vaccinations in the US. Some countries do a lot of them. We don't do a lot of them. And so we don't, we don't have people with a ton of experience in that area. 
  
Emily Reddy:  
So how is our country doing at that right now? 
  
Nita Bharti:  
There's definitely room for improvement. And this may not be the time we wanted to learn as we go, but I think that is a little bit of what's happening. There are plenty of global expertise in this that we, we didn't have to deal with this way. But this is the way that it was done.
  
Emily Reddy:  
So I talked about some of the people who are now eligible people with cancer with immune deficiencies. Is it safe for them to get vaccinated with these, these medical conditions?
  
Nita Bharti:  
Yes, it is safe for them to get vaccinated with these medical conditions. It is, it's important for people who are high risk to get vaccinated in some of these conditions present high risk of negative outcomes or severe negative outcomes from infection. And it certainly, I think, in some cases, would help people who are interacting with the healthcare system more, because they have some of these conditions. It might help them feel safer when they're going to those doctor's appointments.
  
Emily Reddy:  
What about women who are pregnant, nursing or planning to become pregnant? 
  
Nita Bharti:  
So, um, it looks like the vaccine has been approved for those groups. And in that sense, you know, it would be safe. 
  
Emily Reddy:  
How do people know when it is their turn to get vaccinated? 
  
Nita Bharti:  
The way that I have been doing in the way that I think most people have been doing is just check the check the Department of Health website for your state. In a different type of mass vaccine rollout there would be, you know, door to door efforts. There would be workplace efforts. There would be transit center efforts. And we're not we're not doing that. And I think that's a gap. 
  
Emily Reddy:  
I mean, I'm wondering, you know, when this happens at Penn State, whether you know, there'll be big mass events at Beaver Stadium. Or, or, you know, how, how are these vaccinations likely to happen, either at Penn State, but elsewhere? Is it going to be just you got to make your appointment and go to CVS? Or is it, do think that there are going to be these bigger vaccination efforts. 
  
Nita Bharti:  
So it looks like we're starting to see some of these bigger vaccination efforts. There are some cities that are opening up stadiums and things like that for vaccination sites. And that's huge. That's a big important step. College students and colleges -- separate from obviously, medical schools and hospital workers -- college students are probably not going to be getting this vaccine until maybe April-ish. It would certainly be a great move for Penn State to have something set up at the stadium. Because it's open air, and it's a large place. And it's accessible to most students. So that would be a great plan to have something set up at Beaver Stadium. 
  
Emily Reddy:  
What are the potential side effects of the COVID vaccines and which of these are most likely? 
  
Nita Bharti:  
So most likely, what we'll expect to see is that after getting the vaccine, there will be maybe a low grade fever and some soreness or swelling at the injection site. And that's basically a little bit of an indication that it's working, right. So your body is responding to what the mRNA has told it to make, right? So your body receives this mRNA and created this harmless piece of the spike protein of the virus. And then your immune system said, "Hey, let's respond to it and then make a file for it, remember it." Some people are also reporting things like headaches. But there haven't really been a lot of serious side effects. And so that's really encouraging.
  
Emily Reddy:  
Are the side effects more likely in people who are allergic to other things like penicillin, eggs, shellfish? 
  
Nita Bharti:  
That's a good question. So with things like influenza vaccine, we do see that. And it's because the influenza vaccine, we have to grow up the virus in eggs. So there are egg-free influenza vaccines for people who are allergic to eggs. But with this vaccine, because these are mRNA vaccines, there's no growing up of the virus and then purifying. So there's no egg products. There's no shellfish. Those kinds of allergies, we don't expect to be a problem for these mRNA vaccines. 
  
Emily Reddy:  
What would you say to someone who, after hearing this whole conversation is still hesitant to get vaccinated, you know, what's the pitch to them for this being a good idea? 
  
Nita Bharti:  
I think it's always a good idea to find credible information on your own. To do the kind of research and have the kind of conversations that you need to feel comfortable. But it's also important to make sure you're getting that information from credible resources.  So I don't think there's anything wrong with kind of wondering if this is safe or not. It is safe, and it has been proven to be safe. And if it wasn't safe, it wouldn't be approved. And it wouldn't be being distributed. Particularly for this vaccine, because it was done quickly everybody involved knew that there would be questions about how did this happen so fast. There was definitely a very close and careful assessment of safety. Anything that would have undermined the safety of this vaccine, or undermined the public trust in this vaccine would not be worth it. And so a lot of the the COVID vaccine safety protocols are intentionally transparent. They were done extremely carefully because of this.
  
Emily Reddy:  
In your Twitter bio, you say you are an "exhausted epidemiologist," do you have any idea when life for you and all of us might get back to normal? You know, is that time is that I'm going to come at some point? 
  
Nita Bharti:  
Yeah, it's a little bit tongue in cheek, right. So I kind of have the luxury of being able to quarantine and I'm pretty fortunate in all of this. But I think, you know, for most people thinking about going back to normal. Things are gonna look a little different than they used to for quite a while. 
  
Emily Reddy:  
Dr. Nita Bharti, thanks for talking with us. 
  
Nita Bharti:
Thank you so much, Emily. 
  
Emily Reddy:
Epidemiologist Nita Bharti is an assistant professor of biology in the Center for Infectious Disease Dynamics at Penn State. To hear this and other episodes of Take Note go to WPSU.org/TakeNote. I'm Emily Reddy, WPSU.