COVID-19 News & Updates: Get the latest on vaccine development and more.

Steve E. Bishop, M.D.

By: Steve E. Bishop, M.D. on December 9th, 2020

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COVID-19 Update 12/9: Pfizer Vaccine FDA Data

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The FDA has released a briefing document ahead of their meeting tomorrow to consider the Emergency Use Authorization for the vaccine developed by Pfizer. Among other data available, the document outlines the known side effects associated with the vaccine and rates at which they occur. In this week's update, Dr. Steven Bishop walks us through these side effects and answers viewer questions. Watch the complete video below and read on for a transcript.

What do I need to know about the FDA Briefing Document and the Pfizer vaccine trial?  

So today I'm going to spend some time talking about the Pfizer vaccine because the FDA has published their data submission. It's publicly available. Anybody can take a look at that. It is a 53 page document. So, it's not going to take you five minutes. It's going to take you a long time. There's a lot of science jargon in there and a lot of data, but I think it's good to take a look at it. Overall, I'm going to give some general impressions and then we're gonna kinda dive into some of the specific data sets that are listed.


What demographic groups were represented in the trial and which were not? 

Overall, I think that the vaccine study seems to have been done fairly well based on the information that's published here.

They have over 40,000 patients in the trial. If you look at the demographic tables, it actually looks like they've got a good, fairly representative cross section of the population, especially the U.S. population.

One critical group that was excluded from the vaccine trial was pregnant women. So, if they discovered that you were pregnant during the course of onboarding or the trial, you were excluded from the trial. There were some pregnancies by happenstance that they did not know about. And so some pregnant women did get the vaccine, and they didn't report any problems. But there were not a large number of pregnant women included in the trial.

The youngest trial participants were 16 years old, so no one under the age of 16 has been tested.

And they did test people, lots of people, over the age of 55, a fair number of which did have some comorbidities like diabetes, high blood pressure, obesity, things of that nature. Overall, I think that the trial demographics are pretty good and so represent a good swath of the people in the United States. So I think that's good news. If you go to, um, we'll just skip down to page. If you go to page 24, it's table six, if you'd want to follow, you can look and see some of the efficacy data after the second dose.

How effective is the vaccine? 

This is a two-dose regimen. Pfizer and Moderna are both going to be two-dose vaccines, and they're spaced apart by two to three weeks. The number of participants in the vaccine group who had a case of coronavirus during the follow-up period was eight. And the number in the placebo group was 162. So definitely appears that the vaccine does provide protection from COVID. Additionally, there were very few cases of severe COVID in the vaccine group. That is all good news.

According to the data presented here, the vaccine seems to work, and it seems to work in the vast majority of people that were part of the test group, regardless of population demographics.

What are the side effects?

This is what we are all worried about, right? We want a vaccine that works, but we also want one that is safe. Take a look at tables 15, 16 and 17 on pages 34, 33, 34, and 35 of the report. These tables have some of the most important pieces of adverse outcome data in them. 

Pain at the injection site

Relatively minor side effects were common, specifically the pain in the arm, across age groups. A large majority of people, regardless of their age, experienced pain at the injection site after both doses of the vaccine. Just over 80% of patients had pain at the injection site. About 5% had some redness in the arm and about 5 or 6% had some swelling in the arm. Both the 18 to 55 group and the 55+ group had similar side effect rates from the injection itself.

Now, when you get down into table 17 and then table 18, we're looking at the more systemic side effects, the ones that are a little bit more concerning for folks and some of them were pretty common.


After dose one, most people had some fatigue, and about 47% of patients had fatigue after the second dose. Altogether, about 60% of patients had fatigue. 

Cold/Flu-like symptoms

And about half of people had a headache after both doses. And some people, about 14% in the first dose, 35% in the second dose, had some chills. A very small number of people had nausea, vomiting, diarrhea, and a fair number of people had fevers.

So, especially after the second dose about 30% of patients had a fever after the second dose of the vaccine. Only a few percent in the first dose. So, and that was ages 18 to 55.

In the greater than 55 group, the systemic side effects were actually a little less pronounced, probably because the immune response may not be quite as strong in those groups in terms of it reacting to the vaccine, but it was, you know, fairly similar side effects overall.

Similarity to the Shingrix vaccine

It may be a little worse than the Shingrix vaccine. That's for shingles, for those of you who don't know about Shingrix. The shingles vaccine is also a two-dose vaccine regimen. And after the second dose some people do get fever, fatigue, chills. They kind of feel like they have a mild flu for a few days. So not terribly uncommon. But these vaccine side effects are a little bit worse than that.

About 30% or so of patients took a fever reducing medicine after the second dose. So pretty, pretty common to need to do that. And there were some other less likely side effects. So getting some lymph node swelling, things of that nature but, overall, no extremely serious adverse events reported that are linked directly to the vaccine.

What to expect if you get the vaccine?

If you get the vaccine, the Pfizer vaccine, expect to have some side effects, especially after the second dose. Fatigue, mild fever, headache, chills, those sorts of things. You might want to consider taking Tylenol with or after the second dose of the vaccine to minimize some of those side effects. 

Who should get the vaccine?

Most people who are adults should consider getting the vaccine. People who are over the age of 50 or who have medical problems like obesity, diabetes, heart disease, things of that nature need to strongly consider getting the vaccine, because they're at higher risk for doing poorly with coronavirus.

Let's take some questions ...

Do you know if the vaccines were made from aborted tissues?

So you're talking about fetal tissue. That, I am not 100% certain about. There are many different cell lines that are used in development of vaccines, and it's certainly possible that the cell line that was used to help create the vaccine might have come from a fetus at some point. I don't know that for certain. It is certainly a possibility.

There are issues with cell lines in general. How they've been obtained is not always been by the best means. I don't know if anybody's familiar with the story of Henrietta Lacks. Um, there, that is the HeLa cells. There's a whole book about them: The Immortal Life of Henrietta Lacks, and her cells were essentially stolen at Johns Hopkins and used without her permission, et cetera, in medical research for decades and decades. So, certainly possible. I have not seen or read that, but that may be the case. Regardless, that, like I said, that may be true. The vaccine components themselves won't have fetal tissue in them. It'll be purified of any of those cell line things before it's used on people.

I saw on the news today about allergic reactions. What do you know about these findings?

I'm just seeing those reports myself. The UK started administering the Pfizer vaccine in the last couple of days, and they've had a few people have significant allergic reactions to the vaccine. So those are things that would happen pretty much immediately after the vaccine is given. I don't know how many people that has happened to and I don't know how common it's going to be. So, it's something we're going to have to watch and be careful of. And what they're saying right now, by the press releases is if you've got a history of having severe allergies of any kind, maybe hold off on getting the vaccine for now until we have a little bit more information.

How concerned are you about longer-term health impacts on those who survived COVID?

I'm very concerned about that. And in fact, we actually had a meeting this morning with one of the local labs in the area. We are going to start working on putting together a post COVID lab panel. And we've actually started implementing a process, 14 days after people are diagnosed, a screening process, our nurses are calling people and checking on them to ask how they're doing, and if they're having any cardiac or respiratory symptoms still after 14 days.

And if they are, then we will probably be bringing them in for additional labs screening and perhaps some other evaluation, depending on what we find because of those very concerns.

So, we'll probably be checking in some people some cardiac marker or some other inflammatory markers, just to make sure that things are okay especially if they're still having symptoms after the two-week period in which they should be feeling better. So, fantastic question. And yes, we are definitely concerned about that and are working to try to help screen people after the fact.

Will you be totally protected after the vaccine?

So, we hope. That being said, it's not 100%, right?

The vaccine efficacy data is basically showing about 95% efficacy. So some people in the vaccine group did still get COVID. But they tended to get much more mild disease. So you could still get coronavirus, even after getting the vaccine.

Until a large, large percentage of people are vaccinated, probably 70, 80% of the population, I think most people are going to continue to need to be careful, especially if they are higher risk folks, about masking, staying away from crowds, washing hands, all those sorts of good things.

Will vaccines be administered at the doctor's office?

Yes. And other places too. So what I'm expecting is that they'll probably be available at a physician's offices. They'll probably be available at sort of public vaccination sites that are run by the health departments. They'll probably be available at big hospital systems. And then at some point down the line, they'll probably be available at, you know, pharmacy chains, Walgreens, CVS, that sort of thing.

Has the CDC defined, clearly, which populations count is higher risk? I've read media reports that higher risk folks may receive the vaccine earlier than others, but I'm unsure exactly how that is determined.

Yeah. I'm not either, and they haven't released all those details to us yet either. I'm guessing it's going to be both age and then some key diagnoses. So, being overweight, having hypertension, having diabetes, having heart disease, I think those things probably will count most certainly. And other than that it'll probably be age, and it'll depend somewhat on vaccine supply.

It may prove too difficult to stratify things by, you know, diagnosis, cause that can be hard to track. So it may, wind up just being an age thing. You know, if you're 80 and above, then 70 and above, and 60 and above, then 50, and then kind of go from there. But we'll see. I'm not sure. CDC hasn't issued all of the guidance on that. I haven't seen it myself yet.

I heard that you can get the virus after the vaccine. The vaccine just keeps you from feeling sick when you do get it and you can be infected and contagious, but not sick

You cannot get the virus from the vaccine. So the vaccine itself is just a genetic messenger, a tiny component of the virus. So you can't actually get infected from the vaccine, and 95% of the patients in the treatment group in the Pfizer trial were protected from COVID infection of any kind by the vaccine. There were a small number of people who did still get the virus, and they had mild disease. So that, that certainly is possible.

Will you give a quick tutorial on mask and shield wearing inclusive of, how long they can be worn, how often to clean them or wear them?

What I would say for both masks and shields, I would wash or clean them at least once a day, especially if they're cloth masks. Clean them, put them in the wash at the end of every day, or if you get coughed or sneezed on or something like that, then, you know, take it off immediately, swap it out and clean it. The same thing for the shields.

To remove them so as not to contaminate anything, the biggest thing is when you're removing them, don't touch the mask in front. If you can just touch it behind the ears and just peel it off, straight forward, and then put it in the trash. Same thing with the shield, pull it off from the back. Don't touch the front and then wash your hands immediately after removing the mask or the shield.

Do they know what component caused the allergic reactions?

No, we don't. These reactions just happened in the last day or so, so I don't think anybody knows what component of the vaccine is responsible.

Are there any mammal source byproducts contained for those who have alpha-gal syndrome?

I do not know that question, the answer to that question. But could possibly be the case.

I'd rather not be out if necessary, are tele-health exams adequate for regular checkup?

Great question. So what I'd say is for now, if you're concerned about being out, I think that's fine. Do the talking portion of your visit via telemedicine and then schedule the in-person the exam part of things a month or two down the line, so that you still get the exam done.  Hopefully after we've started rolling out vaccine, things are a little bit better. So yeah, I would go ahead and do the talking part now and you know, review the preventative health maintenance and your medicines and make sure all that is squared away. And then you can do the exam part later, and that's perfectly fine. That's kind of what we were doing back in the spring.

I don't think people who exhibit risky behavior should take up space in ICU beds. 

I certainly understand how people can feel that way. You know, I think that the thing to keep in mind is, we try to have a health system that takes care of all comers, regardless of what's going on. Cause you know, we all do have habits and do things that contribute to our illnesses and, you know, in different ways, shapes or forms. And you know, so I don't want to, you know, I don't want us to be getting into a game where we're telling people they can't get care just because they did X, Y or Z thing.

We treat people with lung cancer who are smokers and we treat people with liver cancer who are alcoholics and those sorts of things. So I wouldn't want to address this any differently than those sorts of other medical illnesses. But, yeah, but I understand how some people can feel that way.

I'm hearing, even after vaccine, we still need to practice mask wearing and hand washing till 80% of the population is vaccinated.

Yeah, I think that's true because I think the vaccine, that I think the virus, will continue to circulate fairly significantly in the population until about 70 or 80% of people are vaccinated. That's pretty typical for most vaccines. You have to get to that true herd immunity level before the transmission starts to taper off. So yes, I think that that is accurate.