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Ask a Health Expert Podcast, Episode 1: Vaccine Safety

March 26, 2021


NOTE: Please visit the CDC's website for more information about the Johnson & Johnson COVID-19 vaccine, including information about a very small number of reports involving a rare and severe type of blood clot in people who have received the Johnson & Johnson COVID-19 vaccine. No one has reported similar blood clotting events associated with the Pfizer and Moderna vaccines. If you have questions about COVID-19 vaccines, please talk to your doctor.


Host (Dr. Whitney): Are COVID-19 vaccines safe? How were they developed so quickly? Will I have any side effects? What will life look like after I’m vaccinated?

Hello and welcome to “Ask a Health Expert,” a new podcast series from your health plan. I’m your host, Dr. John Whitney, Vice President here at Anthem.

Tens of millions of people in the U.S. have already received one of the three available COVID-19 vaccines. These vaccines represent an extremely important step towards overcoming the virus. But we know many of you have questions and concerns about these vaccines. So we decided to go straight to Dr. Geoffrey Crawford, a medical director here at Anthem and an expert in public health and epidemiology.

Hey, Dr. Crawford.

Dr. Crawford: Hi, Dr. Whitney. Thanks for having me on the show.


Host (Dr. Whitney): Thanks for being here. So we know that COVID-19 vaccines and the information about them continues to change over time. Our members have a lot of questions when it comes to the vaccines, but the number one question I’m hearing is “Are they safe?”

So can you tell me a bit about how the vaccines were developed? Did this differ from other vaccines in the past? And how did they get it done so fast in months instead of years?

Dr. Crawford:

  • Yeah definitely a great question. There are number of different things going on that led us to be able to develop these vaccines so quickly.
  • The first is that this vaccine is a member of the coronavirus family. There’s other viruses in this family, for example, severe acute respiratory syndrome or SARS. There was an outbreak that occurred in 2002. Another similar virus, the Middle East respiratory syndrome or MERS, there was an outbreak of that in 2012. There was another, also four other viruses in the coronavirus family that cause the common cold, and so the research on these viruses already laid the groundwork for scientists who were studying vaccines going all the way back to 2002 for SARS.
  • We also know that the pandemic was a global emergency and the research effort was therefore collaborative. It brought together people from across the world. Researchers, different governments, lots of funding, and all of this helped to speed up the process. The FDA for example, the Food and Drug Administration, they also decreased some of the regulatory hurdles that slowed the process down, not in a way that compromises safety or efficacy but in a way that makes sure that these vaccines, which are extremely effective, were able to be produced and developed so quickly.
  • It also helped them to launch clinical trials quickly, which are extremely important, bringing together tens of thousands of volunteers to get the data to show that these vaccines are both safe and effective. And then during this entire process, safety was not sacrificed at all.

Host (Dr. Whitney): OK, so they developed the vaccine, but who decides that it’s safe for use in the Unites States and how do they decide if it’s safe?

Dr. Crawford:

  • Yes, so in this country it’s the Food and Drug Administration, or FDA, and they regulate approval or authorization of vaccines. And what they require for this process is a lot of data. And in the case of the COVID-19 vaccines there were tens of thousands of volunteers in each of the clinical trials for each of the vaccines that received authorization. And it was important to have this data to show that it was both effective against preventing COVID-19 as well as safe.
  • We know that there are three different vaccines that are available today by emergency use authorization from the FDA — there's the Pfizer vaccine, the Moderna vaccine, and Johnson & Johnson’s Janssen vaccine. We know there are other COVID-19 vaccines that are being considered by the FDA and they are currently in clinical trials.
  • So clinical trial data is really important, and it’s this data that informs the FDA to make sure that these vaccines are both safe and effective.
  • But there are other public health agencies involved as well, for example, the Centers for Disease Control and Prevention, the CDC, who helps to continue to monitor some of this data after the vaccines are available. They look for both short-term side effects as well as possible long-term side effects. And they look at the many millions of Americans who have received the vaccine as well as the many tens of millions of people worldwide who are receiving these vaccines.

Host (Dr. Whitney): That’s great information. So you think about it, it’s the people in the clinical trials, that’s tens of thousands of people, but then also the millions of people who have gotten the vaccine since they’ve been on the market, and they’re still showing great evidence of safety. That’s good to know. But are they effective? Will they prevent somebody from contracting COVID-19? What about spreading COVID-19 to others?

Dr. Crawford:

  • Yeah, so from these large clinical trials that the FDA helped conduct, we know that these vaccines are all very effective. The Pfizer and Moderna vaccines, these are the first two that were issued authorization, they’re around 94% to 95% effective at preventing you from getting COVID-19 that’s associated with symptoms.
  • For the Johnson & Johnson vaccine, which was authorized a little bit later, it was found to be 66% effective in preventing people from getting moderate or severe disease, and if you just looked at how effective it was in preventing critical or severe illness, it was over or around 85% effective. So this is all really good information showing that it’s effective at preventing serious illness.
  • So we know that they are very effective at preventing serious disease. We don’t know if they are effective at preventing the spread of COVID-19, it’s very difficult to study this. But there is some emerging data showing that they probably are effective at decreasing the chance that you do spread the virus. But because we don’t know for sure, it’s important to follow the recommendations from the CDC, which is changing over time, and that includes continuing to wear masks and social distancing and other preventive measures according to what they are saying.

Host (Dr. Whitney): Well I’m sure a lot of that is because this is all so new, but it’s really important and reassuring to hear that all of the vaccines protect you against severe illness, hospitalization, and death. That seems like the main objective. And I did hear that the CDC had updated their guidance on people who are fully vaccinated being able to gather and not wear masks, and I know that that’s also a changing and dynamic topic but that is such a hopeful step. I’m very excited about it. So the effectiveness may vary a little bit between the vaccines. Are there any other differences that we should know about?

Dr. Crawford:

  • Yes, so both the Pfizer and Moderna vaccines are very similar. They both use something called messenger RNA or mRNA technology, and this is something where it provides your body with instructions on how to make a protein. And in this case, it’s a protein that is found on the surface of the virus that causes COVID-19. And so both those vaccines basically give your immune cells instructions on how to produce this protein. Once that protein is produced, your body produces antibodies or an immune response, and if you ever are infected with the virus that causes COVID-19 in the future, you could rapidly develop an immune response against that virus and protect yourself.
  • The Johnson & Johnson vaccine is a little bit different. It uses something called viral vector technology. Basically what that means is it uses another virus to introduce into your body, in this case the same protein that the Pfizer and Moderna vaccines use to, again, teach an immune response to produce antibodies. In the case of the Johnson & Johnson vaccine, it uses a virus called Adenovirus 26, which is the cause of the common cold. But this is a modified version of that Adenovirus that can’t replicate or cause any illness. All it really does is enter your cells in your body, and then use your cells’ machinery to produce a harmless piece of the virus. Again, the same protein that the Pfizer and Moderna mRNA vaccines teach your body to produce a response against.
  • The Pfizer and Moderna vaccines require two doses and the Johnson & Johnson vaccine only requires one dose.
  • But none of these vaccines can cause you to get sick. They don’t contain the virus that causes COVID-19. They’re really just teaching your body to produce an immune response against a very small, sensitive part of the virus.

Host (Dr. Whitney): Interesting, so that’s a pretty basic thing. If they don’t contain the virus that causes COVID-19, they can’t give you COVID-19, that makes sense. But it sounds like producing this immune response must be associated with some side effects. Can you tell us a little bit about what common side effects people might experience are?

Dr. Crawford:

  • Exactly, it’s very common to develop side effects against a vaccine, and this is a sign that your body is producing an immune response or immunity.
  • And so for the COVID-19 vaccines, like other vaccines, some of the side effects are pain and swelling in the arm where you’ve had the vaccine injected. You might also feel a little more tired, you might develop a low-grade fever. And these side effects are generally pretty short lived, a day or two, but they can last longer in other individuals.
  • We do know that the side effects for the Pfizer and Moderna vaccines, which are given in two doses, they may be a little bit more severe on your second dose.
  • But side effects that are severe, like serious immune responses or allergic reactions, are extremely rare for all of these vaccines. They are really just a handful per million doses administered. So for that reason, after you get your vaccine, you’re observed for about 15 minutes, and in some cases half an hour, to make sure there are no side effects. But those are very, very rare, extremely rare, fortunately.
  • We also know that the CDC is asking people to track their side effects and they have a smartphone-based tool called v-safe. They’re using this tool to track the side effects so that they have as much data as possible to understand how these vaccines are working and to help ensure that they are very safe.

Host (Dr. Whitney): Well that’s good to know that those side effects luckily aren’t serious in most situations. And I did hear about that v-safe app from the CDC, and it’s so important for people to contribute to our knowledge about vaccine safety by adding any symptoms they might have. So one of the things that’s been in the news a lot lately is the variants to the virus. And I’m told that those weren’t that common initially but have become more common over time and so the vaccines may offer different protection against them. Do we know much about that?

Dr. Crawford:

  • Yeah, it’s a great question. So all viruses do mutate over time, and if they mutate enough, they become a variant. So these emerging variants are something that’s not a surprise. Early on during the pandemic, when the Pfizer and Moderna vaccines were being studied, these variants didn’t exist. But we do have some data showing that they look like they should be at least partially effective against these variants, but we need more information.
  • For the Johnson & Johnson vaccine, this was studied a little bit later during the pandemic, and some of the people in the clinical trials enrolled actually did develop COVID-19 from one of these variants. So we do have clinical trial data from Johnson & Johnson showing that the vaccine in that case was effective against some of these emerging variants. Maybe not as effective as the original virus strain, but all data suggests that they should be at least partially effective, which is good news.

Host (Dr. Whitney): That is good news. And I guess that may contribute to the need for boosters in the future, is that the case?

Dr. Crawford: Exactly. If the virus that causes COVID-19 evolves enough that the current vaccines are no longer effective or very effective, it’s possible that we could use booster shots to give our body an updated version of the vaccine that’s more specific to these variants. There could even be vaccines out there that can target multiple variants in one shot.


Host (Dr. Whitney): Fantastic, so I think the scientists are going to stay busy for a while, and it’s just amazing what progress has been made. Alright, I’ve got one more question for you today. When and where can someone get a COVID-19 vaccine?

Dr. Crawford: Great question. I would recommend going to the CDC’s website, That information about who is eligible and where to find the vaccine. Each state has a different plan for how to distribute these vaccines based on identifying individuals who are at risk of either severe disease or at risk of contracting COVID-19 based on their job or occupation. So it is worth checking the CDC’s website to see who is eligible and where to find the vaccine.

Host (Dr. Whitney): Fantastic, you are a tremendous resource, appreciate the information. Now it’s important to note that Anthem does cover the COVID-19 vaccine at 100%, no cost share. So if you have one of our health plans, you don’t have to pay out-of-pocket costs during this national public health emergency. This applies to all of our members, regardless of the type of health plan they have or which doctor or healthcare professional they choose to visit for vaccination. And if you want to learn more about COVID-19 and your benefits, you can visit

Dr. Crawford, I really can’t thank you enough for taking the time to answer our questions today.

And listeners, we do hope you’ll join us soon for another episode of “Ask a Health Expert,” where we will focus on separating facts from myths about COVID-19 and the vaccine.

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Stay informed by checking these resources for up-to-date information about COVID-19, especially if you’re thinking about traveling.