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I Asked a Doctor

A few months after the COVID pandemic began, I wrote a lengthy blog post on the subject with a particular focus on the civil magistrate. Since that time, I've written a few other posts commenting on one aspect or another of the Christian response to the pandemic. One thing I have repeated in all of these posts is that I am not qualified to say anything directly about the virus or the treatments for it because I am not a doctor. In my last post, I said that questions about face masks and vaccines are medical questions and that if anyone had a question about those issues they should ask a doctor.

Given my lack of medical knowledge, not only am I unable to answer the medical questions others have asked me, I myself have questions that I am curious about. So, I asked a doctor.

I thought this might be helpful for me and for others. I decided to ask a doctor who is a member of my local church. His children and my son have taken lessons from our church's music conservatory, so we've been to a lot of the same recitals over the years. His name is Dr. David Koo, and he has been working in a local hospital with COVID patients since the pandemic began. I thought to myself, "Who better to ask than a doctor who is a Reformed Christian and who has direct experience working with COVID patients?"

What follows then are Dr. Koo's responses to some questions that I have been asked and some questions that I wanted to ask -- about COVID, face masks, vaccines, and such.

Can you tell the readers of this blog a little bit about yourself and where you work?

Thanks for having me on your blog Keith!

My family and I moved to Central Florida in 2010. For the last six years, I have been working at AdventHealth Waterman as a hospitalist. Basically, a hospitalist is a doctor who takes care of patients who are too sick to go directly home from the emergency room. I like to describe myself as the Primary Care Doctor inside the hospital. I end up taking care of everything from drug overdoses to suicide attempts to strokes to heart attacks to COVID-19.

How long have you been treating COVID patients?

I have been treating COVID patients from the very beginning of the pandemic. At that time, treating COVID was quite frightening because there was so much mystery. We really didn’t know how contagious the virus was or even the protocols to use. We were making it up as we went along! In those early days, gowning up in “spacesuits” was very foreign to us. Now donning our gear is “just another Wednesday.”

What are viruses and how do they make people sick?

The two main pathogens that cause diseases in humans are bacteria and viruses. The key differences between the two are: 1) bacteria are much larger than viruses, 2) bacteria can self-replicate (viruses need to “hijack” a host’s cellular machinery to replicate), 3) antibiotics work against bacteria (but not viruses). In general, we have much more effective therapies against bacteria than viruses.

The way viruses make people sick varies dramatically from virus to virus. Some only cause a minor cold (rhinovirus). Some directly attack the immune system (HIV). Others damage the liver and increase the risk for liver cancer (Hepatitis C). And others can cause something called a “cytokine storm” that is exceedingly lethal (Ebola).

Is the COVID virus a hoax?

Absolutely not!

Waterman hospital has a capacity for about 290 patients. Right now, there are about 125 scared and struggling COVID-19 patients in the hospital (and all but 6 are unvaccinated). In other words, over 40 percent of the hospital is filled with patients with the same diagnosis.

It’s unprecedented! Within the past 30 days, over 80 people have died from COVID-19 at Waterman. There is a “parade of body bags” coming out of every hospital in Central Florida. Many hospitals in Florida have been on the brink of running out of ventilators.

Is the COVID virus the same as the flu?

Not even remotely close.

In a typical year at my hospital, I will see or hear about 2-3 deaths from influenza within a year. With COVID-19, during this peak I am seeing 2-3 deaths from COVID-19 within a single day. Honestly, I’m not sure how this myth got perpetuated, but it does not comport with reality.

If you look at the mortality data just in the United States, there have been over 639,000 deaths from COVID-19. In that same time, there have only been approximately 30,000 deaths from the Flu.

What is unique about the COVID virus?

COVID-19 is the “Goldilocks” of viruses.

Although frightening, a virus like Ebola will not likely cause a pandemic because it simply kills people too fast and efficiently. Basically, people get sick and die before they can spread it to others.

COVID-19 however is much more insidious than Ebola. There are many people who will only get minor cold-like symptoms. There are even those who have no symptoms at all but are “spreaders” of the virus.

But here’s the frightening rub: there are a significant number of people—and it is incredibly difficult to predict who they are—who will respond violently to COVID-19. These will end up in the hospital and on a ventilator. Then when even the ventilator cannot supply enough oxygen, these patients will die.

How does the COVID virus cause death?

You basically suffocate or “drown” within your own inflammatory secretions.

Like Ebola, COVID-19 can cause something called a “cytokine storm.” Basically, your lungs fill up with inflammatory fluid. And it’s not something that can be drained—imagine a sponge soaked with watery Jello mix and then placed in the refrigerator. It’s a terrible (and lonely) way to die.

What are variants such as the delta variant? Are they more dangerous?

The delta variant is more contagious and deadly. At my hospital, during this current peak from the delta variant, the total number of hospitalized COVID-19 patients is more than 2x higher than the previous record. And those who are dying from the delta variant appear to be much younger.

What is the mortality rate for COVID?

When people ask this question, what they are asking is this: “What are my chances of dying if I get COVID-19?” And the number that answers this question is called the “Infection Fatality Rate” (or IFR). This number is simply calculated like this:

Deaths from COVID-19


Actual number of people who get infected by COVID

Unfortunately, this is an extremely difficult number to pin down since the denominator is extremely difficult (and expensive) to determine. Also, this number varies greatly depending on many factors.

But in the grossest and most general sense, the IFR is estimated between 1 in 500 to 1 in 100. But if you have significant risk factors, your risk could be as high as 1 in 10. And if you have some sort of genetic predisposition (which we don’t completely understand), your risk could be as scary as 1 in 2. For example, I took care of a family where a daughter lost both of her grandparents and father to COVID-19. And I took care of another man who lost both his wife and son within 4 days. Statistically, this should be extremely rare to nearly impossible, but we are seeing this not infrequently with the delta variant. My hypothesis is that these families have some sort of genetic predisposition to developing cytokine storm with COVID-19.

So, is your risk of dying 1 in 500? Or is it 1 in 2? The truth is that nobody knows until you get infected by the virus. It’s a crapshoot.

"But," you say, "my pastor and friends tell me that the fatality rate of COVID is extremely low—as low as the Flu. I’m confused."

There is another fatality calculation that is commonly used called the “Population Fatality Rate” (or PFR) when assessing risk. This is calculated as follows:

Deaths from COVID-19


The entire population of the United States

Towards the beginning of this pandemic, the number of deaths in the U.S. from COVID was around 159,000. And the population of the U.S. is estimated at around 328,200,000. So the PFR early in the pandemic was calculated as follows:


—————— = 0.00048


Or 0.048 percent! Or approximately 1 in 2,000. That sounds like pretty good odds to me! If someone said to me, “I’ll give you ten million dollars if you are able to jump from the top of this building to the next,” I would then ask, “What are my odds of dying?” And if he was omniscient and truthful and said, “Your calculated odds of dying are 1 in 2,000,” then I might jump! (Actually, I wouldn’t, but this is hypothetical so work with me.)

So, in terms of COVID what does the PFR mean? Does this mean that my chance of dying of COVID in the U.S. at that time was only about 1 in 2,000? Well, in a very, very crude sense: Yes. And that’s why you sometimes heard people say that you had about the same chance as getting struck by lightning (about 1 in 3000 lifetime chance). BUT (and this is a very BIG BUT) the reason your risk was so low early on was because very few people in the U.S. had been infected by the virus, and so they couldn’t spread it! Remember, only about 2 percent of the U.S. population had been infected back then. However, as more people in the U.S got infected, the PFR went up (WAY UP!). Now the PVR is closer to 1 in 500.

Also, early in the pandemic, the PFR did NOT tell us ANYTHING about how dangerous a virus is. In other words, it does not answer the crucial question, “What are my chances of dying IF I get infected by COVID?” Again, the reason is because, at the time, most of the U.S. was not infected by COVID.

Let me give you an example using Ebola. If you look at the PFR for Ebola during the 2015 outbreak, the ratio was astronomically low! Minuscule! Not even worth talking about! The reason is because compared to the entire population of Africa, the number of people who died from Ebola was relatively low. Why? Because the virus was contained and very few people were infected and died. However, NO SANE PERSON would say that because the PFR for Ebola was so low, it was therefore not a dangerous virus! The same thing applies for COVID (although people use the PFR in this manner all the time). The PFR is simply an astronomically poor estimate of how dangerous a virus is.

Unfortunately, at the beginning of the pandemic, many lay people and even prominent pastors used the PFR to estimate the danger of COVID. This was unfortunate since it has caused a lot of confusion.

What factors affect the mortality rate?

Age and obesity seem to be the most common risk factors that we see in the hospital. But with the delta variant, we are also seeing many young people and those with few risk factors succumb to the virus. Within the past month, we have had a 22-year-old, a 33-year-old, and many in their 40’s and 50’s die from the virus. I currently have a 31-year-old woman who just gave birth to a baby almost die. That was incredibly stressful and frightening. Thankfully, she appears to be slowly recovering.

Are face masks effective in preventing the wearer from catching or spreading this virus?

No prevention strategy is 100 percent effective.

Masks do help, but not in ways that most people expect. When a person sneezes, no small piece of fabric will prevent respiratory droplets from leaking out of the sides and bottom. But—and this is important!—a mask will decrease the “viral load” that a person is exposed to.

In some ways, COVID-19 is like a poison. Consider cyanide for example. At low doses—like the amount found in apple seeds—cyanide will not kill you. But at high doses, it is obviously lethal. Similarly, your body’s immune system may be able to fight off small amounts of COVID-19. However, an overwhelming exposure (like someone sneezing in your face) could be fatal. Masks can significantly reduce the “dose” of your exposure.

When should a person wear a face mask? When is it unnecessary?

For this question, I will defer to the CDC, who currently recommend (as of August 31, 2021) that we should be wearing masks (even if vaccinated) when we are indoors.

Listen, I know that there are many people who are not fond of the CDC because they feel the CDC is constantly backtracking on recommendations, and that causes confusion and distrust. Unfortunately, that is the nature of science. Doctors and researchers can only make recommendations based on the best data they have at hand. And sometimes that data is “not as robust” as they would like. When new evidence arrives that is better than the old, recommendations naturally change. That’s just the way medicine works. I can give many examples where medical recommendations have done a complete 180 degree turn as better powered evidence came out.

Honestly, if the CDC never backtracked on their recommendations, that would make me extremely suspicious. I would think that they were too concerned about “saving face” rather than giving recommendations based on the most current and reliable data.

Does the COVID virus create problems for hospitals in the treatment of non-COVID medical issues such as cancer or heart attacks?

Currently Waterman is at “Code Black”. Basically, all non-critical surgeries and functions are shut down. This is to divert nurses and other resources to take care of COVID patients. Open heart surgeries, cancer surgeries, and other important procedures are currently on hold. Hospitals are overwhelmed. There is no question that many non-COVID patients are being adversely affected by the current surge. Some have had heart attacks waiting for their open-heart surgery.

Can you explain in general what vaccines are and how they work?

Your immune system is an unfathomably amazing and intricate creation of God! It is extremely effective at protecting you from the millions of bacteria and viruses that are trying to kill you every day. However, sometimes a new pathogen will come around that overwhelms your immunity. That’s where vaccines come in—they simply train your immune system to recognize and fight the intruder before you get infected. It is like the difference between a mugger attacking someone with no self-defensive training vs. someone who is an expert in mixed martial arts. The MMA fighter can cause some serious hurt to the bad guy!

Many Christians have concerns about vaccines in general and many also have concerns about the COVID vaccine in particular. Should Christians be concerned about vaccines in general? Why or why not?

If you combine ALL the medical therapies doctors and researchers have developed over the past century including amazing things like organ transplants, open heart surgeries, interventional radiology procedures for strokes, novel treatments for diabetes, and a myriad of medications for hypertension, NOTHING remotely compares to vaccines in terms of cost effectiveness, safety, and the sheer number of human lives saved. This is not an exaggeration in the slightest. They are truly the unsung hero of medicine. It is estimated that they save about 10 million lives each year.

It was not that long ago that huge swaths of the population were wiped out from terrible diseases such as smallpox and polio. Now these diseases are almost unheard of. Vaccines are truly part of God’s common grace to mankind.

Through the years, the safety of these vaccines has improved dramatically. Early vaccines (especially the live vaccine for polio) had more problems and sometimes caused low grade infections and sometimes febrile seizures. But nowadays, the modern vaccines are incredibly safe.

How do mRNA vaccines work? Do they alter your DNA?

The way vaccines work is by introducing an “antigen” into your muscles which trains your body to recognize the virus. Traditionally, this antigen was either a virus that was made less virulent (so it wouldn’t kill you) or a completely inactivated virus. The “messenger” RNA (mRNA) vaccines work a little differently. Instead of directly injecting parts of a weakened or killed virus into you, the vaccine injects mRNA. Your muscle cells then take this mRNA and construct a protein that looks remarkably like a part of the COVID virus call the “spike protein” (those bumpy things on the surface of the COVID virus). Then miraculously, your immune system realizes that this spike protein is not a normal part of your body, and it goes to work developing antibodies against this foreign “intruder.”

It’s important to note that the mRNA does NOT replicate. It does not get incorporated into your DNA. As the name implies, it is truly only a “messenger” between your DNA and the cellular machinery that translates that message into amazing protein structures. Once the mRNA is used up, it is simply eliminated from your body. That is one reason why long-term adverse effects of the vaccine are highly unlikely.

What most people do not realize is that some viruses can in fact change your DNA. It is well documented that certain viruses often incorporate their genome into their host. That is one of many reasons why some viruses can cause cancer years down the road. Human Papilloma Virus, for instance, can damage chromosomes and genes where it inserts its DNA into human DNA which may eventually lead to cervical cancer.

So, can COVID-19 alter your DNA and cause cancer? It is unlikely because of multiple complicated reasons. Nevertheless, if you are worried about this unlikely event, then you should be much more worried about COVID virus changing your DNA than the mRNA vaccine (which has no ability to do this).

The main concern about vaccines of all kinds seems to be the question of whether or not they are safe. Are vaccines safe? Is the COVID vaccine safe?

Let me give you my personal experience with the vaccine. During this entire pandemic, neither I nor any of the other hospitalist at Waterman Hospital have EVER admitted a patient to the hospital because of a complication from the vaccine. So far, about 4 million people in Central Florida have received the COVID-19 vaccine. If there were significant adverse effects, we would have known about it by now.

In very rare cases, the Pfizer and Moderna vaccines may be “associated” with inflammation of the heart muscle (myocarditis) or inflammation of the outer lining of the heart (pericarditis) in 12.6 cases per million. But many of these cases will spontaneously resolve.

The Johnson and Johnson vaccine reported a small number of people with a rare neurological disorder (Guillain-Barré syndrome) and a rare but potentially deadly blood clotting disorder (Central Venous Sinus Thrombosis). Out of an abundance of caution, the FDA placed a halt to the administration of the vaccine. But now the ban on this vaccine has been lifted mostly because the benefits of the vaccine outweigh the potential risks (i.e. it would save many more lives than it would harm).

Some people who have received the COVID vaccine have later contracted the disease. If the vaccine doesn’t prevent one from catching the disease, why should a person get the vaccine?

The COVID vaccines are not 100 percent effective at preventing an infection. But it is up to 94 percent effective at preventing hospitalizations and death. The vaccine could save your life! That’s a very good thing! The vast majority of patients in the hospital who are fighting for their next breath are unvaccinated. The saddest part of this current surge is that these deaths could have been mostly avoided. I have seen doctors, seemingly out of nowhere, break down in tears. A couple of weeks ago, another doctor shared with me that she thinks she is going to need counseling when this pandemic is done. It’s tough to see young people die when we know deep down it was likely preventable.

Are there some vaccinated patients who still end up on a ventilator and die? Yes. Is it common? No, very rare. It is estimated that about 5 percent of those who receive the vaccine are “non-responders”—they never develop protective antibodies. We don’t know why. But most vaccinated people are significantly protected against hospitalization and death.

Another significant benefit of the vaccine is this: it reduces the number of days that you can spread COVID to others. In Israel where 80 percent of the population got vaccinated, the spread of the virus dropped 30-fold! As a Christian and doctor, I feel like I have an obligation to protect those who are vulnerable (even if they do not wish to protect themselves).

Now it is true that currently Israel is going through another spike despite its high vaccination rate. The reason for this is likely from waning antibody response after 6 months—hence the need for a booster. The good news is that despite the spike, the vaccines continue to be highly effective at reducing hospitalizations and deaths. Currently the CDC is monitoring when to begin starting booster shots in the U.S. for the public—likely in the fall.

Since the vaccines began to roll out early in 2021 has there been any evidence that one brand of vaccine is more effective than another?

The mRNA vaccines appear to be more effective. Personally, I would get the mRNA vaccines (Pfizer and Moderna) over the Johnson & Johnson vaccine.

Some have expressed concerns about potential long-term side-effects of the vaccine. Should that be a concern?

Because the COVID vaccines do not stay in the body and do not replicate, the long-term safety of the vaccines is likely excellent. Any side effects typically present within the first two weeks.

Honestly, people should be much more worried about the long-term adverse effects of COVID-19. Assuming you don’t die, COVID has the potential for permanent lung damage, permanent loss of smell (and therefore taste), and post COVID syndrome. And there may be other unforeseen consequences to the virus that we simply do not know about.

Some have expressed concern that the COVID vaccine contains cells from aborted babies or was developed from the cells of aborted babies and therefore no Christian should receive the vaccine. How do you respond to this?

As a Christian, this concerns me too. Neither the Pfizer nor Moderna vaccines are produced using cell lines from aborted babies. The researchers did use some of those cell lines during the initial testing phase. But the final product contains absolutely no lineage from aborted tissue. The Johnson & Johnson vaccine, however, is manufactured using fetal cell cultures PER.C6 which was developed from retinal cells from an 18-week-old fetus aborted in 1985.

Some claim that many doctors and nurses are refusing to get the vaccine because they know how unsafe it really is. Is this true?

At my hospital, most doctors (including myself) are politically conservative. We believe that socialism is bad for society. We hate big government. We believe in free speech and hate the censorship culture in America. And yet, we strongly believe in the vaccine. In fact, I do not know a single hospitalist at Waterman that is unvaccinated despite the proclivity of conservative people to distrust the vaccine. Of course, I am not that naïve to believe they don’t exist. It is simply a tiny minority within my hospital.

Really, being a physician is not unlike other profession. Let me illustrate—let’s say that you have a leak in your ceiling, so you get recommendations from 10 different roofers. The reality is that 7 of those roofers will analyze the situation and give the same plausible diagnosis, 2 of those roofers may offer a slightly different opinion, and 1 of those roofers probably should lay off the marijuana. Physicians are no different—there are some who should lay off the weed.

At my hospital (and many hospitals across the nation), the vaccination rate among nurses is disappointing. I do not question their dedication to their jobs and their love for their patients. I’ve asked them why they don’t want the vaccine. For some it is because they don’t want to be forced to do something they are not completely comfortable with (because nurses across the country are facing tremendous pressure to get vaccinated by hospital administration). For others, they are waiting for the FDA to approve the vaccine (by the way, the Pfizer vaccine is now FDA approve). For a few it is because of more political reasons. There does not seem to be a single overarching factor.

What do you think of the theory that the COVID vaccine implants microchips in your brain?

What? No. I don’t know what website folks are visiting, but it’s time to take a few steps away from the cliff.

Does the COVID vaccine cause fertility issues.

There is no evidence that the COVID vaccine causes fertility issues. In a in vitro fertilization study, researchers found no difference in pregnancy success rate between women who were vaccinated and those who were not.

Some have suggested alternative preventative and treatment measures. How do you respond to those ideas?

When COVID patients are going south fast, we literally throw the kitchen sink at them. I am willing to use almost any medication that the patient or family ask for (if the hospital stocks it). Ivermectin? Fine. Remdesivir? Sure. Vitamin C? Already prescribed. Zinc? No problem. High dose steroids? Yup. Antibiotics? Not sure how that helps with a viral infection, but sure. What about experimental biologic agents such as baricitinib that are typically reserved to treat Rheumatoid Arthritis? I’m way ahead of you.

So, do these therapies work? Well, I don’t know for sure, but they don’t seem to. I frequently have patients on a cocktail of literally 7 different medications, and they still end up on the ventilator and then die. Here’s a clue that doctors don’t have a good treatment for COVID: we are prescribing Vitamin C and Zinc for a deadly pathogen! When you see that, it means we are mostly making it up. I frequently joke that a monkey can do my job treating COVID. And in some sad literal sense, it’s true—if a monkey decided to treat every COVID patient with a diet exclusively of bananas, it probably would work about as well as the random cocktail that I throw at my patients in the hospital.

Also, don’t expect that multivitamins and herbal supplements will protect you. With over 217 million cases of COVID around the world, we would have discovered this magic substance by now. Trust me, doctors and scientist have friends and family that they want to save and protect just as much as anyone else.

Get the vaccine. It is much safer, cheaper, and way more effective in keeping you from dying. Honestly, it really makes no sense be worried about the long-term safety of the vaccine but not be worried about the possible adverse effects of this experimental mishmash of poorly investigated medications that we are prescribing under the FDA’s Emergency Use Authorization. And guess what? Virtually nobody refuses being “experimented on” with these drugs when they are struggling in the hospital wondering what tomorrow will bring.

If someone has already had COVID and recovered, has their immune system been conditioned in the same way it would if they received the vaccine? As a follow-up, should someone who has recovered from COVID receive a COVID vaccine? Why or why not?

Good questions! I got COVID earlier in the year. And I still got both Pfizer vaccinations. And recently, I got another booster!

The problem right now is that we have A LOT more data regarding the efficacy of the vaccine than we do regarding natural immunity. And although I have no doubt that natural immunity will provide protection, I don’t know for how long and against what strain.

Finally, there is little to no downside to getting the vaccine, so it just makes sense to get it for extra protection. It gives me a little more peace of mind that I’m protected and that I’m trying my best not to spread COVID to my vulnerable patients and friends.

Anecdotally, the reaction to the vaccine seems to be stronger after getting a COVID infection. Personally, I had flu-like symptoms for a couple days, but then the fever, chills, and aches went away quickly.

For those like myself who have no background or expertise in medicine, how would you recommend that we sort through all of the conflicting information that we hear online, at church, and from friends and family?

That’s an excellent question! COVID-19 has generated such a mountain of data unlike anything we have ever seen before. And to the layperson, much of it seems contradictory. You have one high quality observational study from Henry Ford that suggests that hydroxychloroquine may be beneficial. Then you get multiple double-blind, placebo-controlled, randomized trial (maybe with some limitations) that show no benefit. Who do you believe? It is the complicated problem of medical epistemology (i.e. how do you determine the truth in medicine). Most doctors have some training in interpreting scientific studies, but my guess is that less than 5 percent of doctors feel they are competent at it. It is incredibly complicated, and honestly more challenging than “brain surgery” and “rocket science.” I have more experience than most doctors because I was faculty at a residency program, but even I am a novice compared to some of my mentors.

Here’s my recommendation: go with the basic raw data that does not require a massive amount of statistical analysis and that is essentially incontrovertible. For example:

  • Over 635,000 people have died from COVID in the United States. And during that time, only about 30,000 have died from flu.

  • The local hospitals report being overwhelmed by patients with COVID-19 and almost running out of ventilators, which never happens with the flu.

  • Local hospitals report alarming death rates from COVID-19.

Then, when someone says, “COVID-19 is just like the Flu,” test that assertion against the reality of the basic raw data. If they don’t match, then there is likely something wrong with the assertion. Here’s another example:

  • Over 4 million people in Central Florida have received the COVID-19 vaccination with very few reports of adverse effects.

  • Over 173 million people in the United States have received two doses of the COVID-19 vaccination with very few serious side effects.

  • Doctors are reporting virtually no hospitalizations because of adverse effects of the COVID-19 vaccination.

Then, when someone says, “the COVID-19 vaccine is unsafe,” test that statement against the reality of those facts. If it doesn’t jive with reality, then it probably isn’t true. As some people like to say, “Facts don’t care about your feelings.” Put your feelings aside and focus on the basic facts of the case.

Now, regarding complicated issues such as which medication is best for treating those with COVID-19, we will have to defer to the experts in the CDC and other medical societies. I know that doesn’t feel good to some people because there is a general distrust of government institutions and big pharma. I get that! But just remember that doctors as a group (including those in the CDC) are not monolithic. What I mean is that we come from many different backgrounds, cultures, and worldviews. We are often vocal and opinionated and sometimes disagreeable, and it is frequently hard for us to form a consensus on many issues. In fact, trying to “manage” a group of doctors is often described as “herding cats.” So, to say that you cannot trust doctors because they are part of the “medical establishment” is sort of laughable. These people have obviously never seen a group of doctors work together! And that is the key point: when most of these cantankerous (but caring) doctors actually agree that the vaccine is safe and effective, it means something.

As a doctor who has been working with COVID patients for the last two years and as a Reformed Christian, what encouragement would you offer to other Christians genuinely struggling with whether or not to receive the vaccine?

In this difficult political climate where we are rightly worried about losing our personal liberties and individual rights, there is still a pressing Biblical mandate to care for our brother, to serve others, to protect the weak, and to consider the needs of others before ourselves. One reason why I decided to get both Pfizer vaccines (and the booster 6 months later) even though I had already gotten COVID early on was because I did not want to be the cause of someone else’s suffering and death. I wanted to do my best to protect my family, friends, and patients. And I honestly did not want to risk my children growing up without a father.

Finally, I want to end with this: I really do not think that I can change anyone’s mind. It is not my responsibility to do so (and it would be too much of a psychological burden). All I can do is present as honestly and accurately as possible what I see every day in my hospital. After that, it is up to each person to decide what to do next. Please know this, whether you decide to get vaccinated or not, my love and care for you will not change. And I will keep you and your family in my prayers.

Thank you, Keith, for allowing me an opportunity to share my experiences. It has been an honor and a privilege.


NOTE: If you have follow up questions about anything Dr. Koo said, go get a second opinion. But get that second opinion directly from a doctor - not someone who plays a doctor on the internet. The Internet is not a doctor. News reporters are not doctors. I am not a doctor.

UPDATE SEPTEMBER 16, 2021 - After I posted Dr. Koo's responses to this list of questions, several readers of this blog contacted me with additional questions. I forwarded these to Dr. Koo, and he was gracious enough to take time out of his busy schedule and respond. These follow-up questions and his responses are listed below:

What are antibody treatments? Have they proven effective?

First off, let’s talk about antibodies. Antibodies are tiny “Y” shaped structures made by specialized immune cells (called B-cells) that stick to and help neutralize foreign invaders like the COVID-19 virus. Unfortunately, unless you have been previously infected by COVID-19 or you have been vaccinated, these protective antibodies are non-existent in your blood—you are simply not protected!

In the beginning of the pandemic, researchers had a brilliant idea: what if they took plasma (i.e. blood with all the cells removed) from previously infected individuals (also called “convalescent plasma”) and then transfused it into sick, hospitalized patients with COVID-19? The theory is that the antibodies from these previously infected individuals would neutralize the COVID-19 virus. And voilà… instant cure! Did it work? Unfortunately, no. After a large randomize controlled study in The Lancet came out in May 2021 showing no benefit, hospitals across the nation stopped using convalescent plasma.

What are monoclonal antibodies? Is Regeneron effective in treating COVID?

The antibodies found in convalescent plasma are made within the human body. Monoclonal antibodies are different in that they were manufactured in a lab. There are several benefits of “manufactured” antibodies: 1) you are not getting a blood product so there is no risk of getting a blood borne infections such as HIV, 2) risk of an allergic reaction (i.e. transfusion reaction) should be much lower, 3) the amount of antibodies administered to patients can be much higher, and 4) the antibodies can be specifically tailored to specific COVID variants.

In the United States, REGN-COV2 (made by Regeneron) is the most common monoclonal product in use. It is comprised of two different antibodies: casirivimab and imdevimab. In a preliminary study, this cocktail appears to reduce the risk of hospitalization and death from mild to moderate COVID-19 infections by about 70 percent. This is a promising treatment option! But REGN-COV2 should be given as early as possibly (preferably within 7 days of initial symptoms).

It’s important to note however that this treatment does NOT replace immunizations. Immunizations may prevent you from ever getting infected. Monoclonal antibodies are only given after you get infected. In order words, with immunizations you are building a “defensive shield.” With Regeneron, you are just doing “damage control.”

Is it true that the CDC’s own VAERS website shows that thousands have died from the COVID vaccine?

This is an excellent question! And the answer is a little technical (but interesting)…

Co-managed by the CDC and the FDA, the Vaccine Adverse Event Reporting System (or VAERS) is a method for anyone to report a possible adverse event related to a vaccine licensed in the United States. Healthcare professionals and vaccine manufacturers are required to report certain adverse events (even if they are not sure that the vaccine caused the event). Think of VAERS like an “early warning system” for vaccines.

Although this data provides valuable information, there are at least two significant limitations to this type of “passive surveillance system”. First, VAERS relies on people voluntarily reporting events. This often leads to “underreporting” which happens more often with minor events than with major events—doctors don’t care about reporting fevers and muscle aches (which are expected with many vaccines), but they will typically report a case of Guillain-Barré Syndrome which is very rare.

Second, VAERS cannot identify cause-and-effect relationships. In other words, if a person gets a vaccine and then dies two days later, this type of reporting system (which, if you think about it, is just a rough “observational study”) cannot determine if the patient died from the vaccination or from a natural cause. When you give a vaccine to millions upon millions of people, some of those people will die of natural things like heart attacks and stroke that may not be vaccine related. Unfortunately, this is a limitation of all observation studies. Because they are not “randomized” or “controlled” (more on this later), they all suffer from “confounding variables” skewing the data.

So, regarding the COVID-19 vaccines, were there thousands of deaths reported to VAERS? Yes. Was this unexpected? No. As of September 2020, about 179 million people in the U.S. (many of whom are elderly with significant medical problems) have been vaccinated against COVID-19. It was expected that some of these people would die of natural causes. When compared to U.S. population mortality data, these numbers did not trigger any alarms for the FDA, CDC, or the medical community at large.

Again, observational studies (like VAERS) cannot determine cause-and-effect relationships because they are not designed to eliminate confounding variables. To do this, you must perform something called a “randomized controlled trial” (RCT). Basically, you randomly divide a population into two groups: one who will receive the vaccine and another who will receive a placebo (or “fake” vaccine). Then after a certain amount of time has elapsed, you measure the adverse events (say deaths) in both groups. In both groups, you will expect a certain number of deaths. But because you now have a “control group” (the population that received the placebo), you can now make some useful comparisons between the vaccinated group and the non-vaccinated group. In multiple RCTs for the COVID-19 vaccines, there was no increased risk of deaths. Now, it is true that these RCTs were not “powered” to detect these exceedingly rare events. That is one of the limitations of RCTs—they are expensive, complicated, and time consuming. Therefore, doing an RCT on millions of people is typically not feasible.

On August 25th, 2021, a very large observational study was published in the New England Journal of Medicine. In this study, the researchers mined the data from the largest health care organization in Israel to evaluate the safety of the Pfizer vaccine. Although this was not an RCT, this study matched vaccinated persons to unvaccinated persons using various sociodemographic (age, sex, ethnicity) and clinical variables (COVID-19 risk factors, underlying medical conditions)—that way they had a “control group”. This was a big study—each group had about 884,828 persons!

Here’s what they found out: the vaccinated group did not have an elevated risk for most of the adverse events that they evaluated. The vaccinated group did have a small increased risk of myocarditis (about 1 to 5 per 100,000). But to put that number into perspective, getting a COVID-19 infection also has a significant risk of myocarditis (estimated at 11 per 100,000). In other words, your risk of getting myocarditis is likely higher with the COVID-19 infection than with the vaccine! There was also a small increased risk of Bell’s palsy and appendicitis, but these finding are not unexpected since vaccinations stimulate your immune system. In conclusion, this large observational study (with a “matched control”) demonstrated significant safety of the Pfizer vaccine.

Is the natural immunity resulting from a COVID infection better or stronger than the immunity resulting from the COVID vaccine?

Maybe. There are some very interesting recent studies on natural immunity which show that antibody response and “cellular immunity” may persist longer for those with previous COVID-19 infections than the vaccinations. However, these studies have several limitations.

First, most of these studies are not “outcomes” data. What this means is that these studies do not look at hard “clinical” endpoints like “hospitalizations” and “deaths.” Instead, they look at the “amount of antibodies” in the blood or the “amount of memory B-cells” that persist after a certain number of months. Unfortunately, having “non-clinical” endpoints may or may not correlate with real life benefits. The human body is exceptionally complicated and often defies our presuppositions. The studies that change the course of medicine tend to be “outcomes” driven. For example, I could care less if a particular cholesterol medicine will decrease your blood cholesterol by 80 percent if it doesn’t reduce your risk of getting a heart attack. My goal as a doctor is not to make a number on a piece of paper look “prettier”—I actually want to prevent you from dying! Believe it or not, there are some prescription medications that make your cholesterol numbers look better (sometimes significantly better), but they don’t do a lick to prevent you from getting a heart attack. I don’t prescribe those medications.

Second, many of these studies are “observational studies” with all the “confounding variables” that can occur. What we really need are randomized controlled trials that compare three groups: 1) those who have been vaccinated but not infected with COVID-19, 2) those who are infected with COVID-19 but not subsequently vaccinated, 3) those who are infected with COVID-19 and then given the vaccination. Then, after a certain amount of time has elapsed, compare the hospitalization rate, deaths, and adverse events in all three groups. I can tell you right now that this type of RCT will never get done. Why? Because it is utterly unethical. To do this type of RCT, you must purposefully infect a randomized group of people with COVID-19. Not! Going! To! Happen! Ever!

So, with the limited (but admittedly fascinating) data on natural immunity that we have so far, the CDC currently recommends that all people in the U.S. (including those who have natural immunity because of a previous COVID-19 infection) get the vaccination. This recommendation may change, however, once more research comes out (even if that research is not from RCTs). Also, if our vaccination supply in the U.S. ever became constrained, my guess is that the CDC would prioritize the vaccinations to those who do not have natural immunity first.

Finally, even if natural immunity is better than vaccination, this does not mean that folks should purposefully try to get infected by COVID-19 instead of getting the vaccine. That would be incredibly dangerous! Please just get the vaccine. Then your risk of hospitalization and death will be substantially reduced. And if you happen to get COVID-19 infection later (don’t try to get it on purpose), you will likely have the benefits of both the vaccination and the natural immunity.

Can you explain what is going on in Israel? Is it true that vaccinated people are being hospitalized in large numbers?

The data from Israel is exceptionally interesting. Why? Israel had some of the highest vaccination rates of any country and had been touted as a model for its rapid rollout of the COVID-19 vaccines. By late February, about 50 percent of Israel had received at least one dose of the Pfizer vaccine. This early rollout was one factor that caused a 30-fold drop in new COVID cases from April to late June! But starting around early July, Israel started to see a large spike in new cases. And many of these infections were in people who were previously immunized. What’s going on?

Antibody levels naturally decline over time thus offering less protection against COVID-19 infections. Since Israel was a very early adopter of the Pfizer vaccine, many vaccinated people had low antibody levels by early July. This likely caused the large spike in new infections. This was bad news to many who were hoping that “herd immunity” would finally wipe away the virus. However, the news was not all bad.

Despite the large rise in new COVID-19 infections (even among the vaccinated), the Pfizer vaccine continued to offer significant protection—about 90 percent! —against serious illness and death. With the number of new infections that Israel was seeing, there should have been a linear increase in hospitalizations and deaths. That never happened. Sure, there was an increase, but not nearly as high as it should have been if the vaccine did not work. So now what’s happening?

Have I mentioned that the human immune system is amazing? Once exposed to the vaccine, the immune system has a “backup strategy” (in the form of “memory T-cells” and “memory B-cells”) that “remembers” what the spike protein looks like. So, if you are infected with the virus, your “killer” T-cells go to work destroying those infected cells. And your B-cells start churning out oodles and oodles of new antibodies. Yes, you still get infected because your initial blood antibody levels have waned, but you won’t likely get a severe illness or die because this backup system (trained by the vaccine) prevented an overwhelming infection.

Do you want more good news? Early data shows that a single booster restored blood antibody levels, significantly preventing new infections. So, are boosters (like the flu shot) likely in our future? Probably.

Is the COVID vaccine dangerous for a pregnant woman and her unborn baby?

Because pregnancy is a risk factor for severe illness from COVID-19, the CDC and American College of Gynecology “strongly recommend” that pregnant women get the COVID-19 vaccination. In some hospitals in Central Florida, there have been as many as 3 to 4 pregnant women daily on ventilators within a single hospital during the peak. Some of these women even had miscarriages while on the ventilator. ICU nurses were traumatized because they were not trained to witness spontaneous miscarriages. This has all been extremely stressful and sad.

So is the COVID-19 vaccine safe during pregnancy? Early data on the safety of the mRNA vaccines (Pfizer and Moderna) during pregnancy are encouraging. There was no evidence of adverse events to the mothers or babies, and there was no increased risk for miscarriages.

For those pregnant women who have already recovered from a COVID-19 infection and therefore should have natural immunity, I would discuss the risk and benefits of vaccination with your obstetrician.

Do any pre-existing conditions make the vaccine more dangerous than the virus?

If you had a severe allergic reaction to a previous COVID-19 immunization, polysorbate (found in some vaccines or coated tablets), or polyethylene glycol (found in some laxatives), then you should talk to an allergist before proceeding with the vaccine. Also, if you have a history of myocarditis, pericarditis, clotting disorders, or Guillain-Barré Syndrome, then talk to your doctor before getting the vaccination.

Otherwise, there are no specific contraindications to getting the vaccine. Even if you have serious medical problems, the risk of dying from a COVID-19 infection is vastly greater than from the vaccination.

What is your opinion on forced government vaccine mandates?

I do not like them. Since many people understandably distrust the government, any forced mandate will only build distrust in the vaccines. Although they may increase vaccination rates in the short-term, my view is that they may hinder vaccination rate in the long-term. And let’s face it, fighting COVID will be more like a marathon than a sprint. It will require those attributes needed for winning any long, drawn-out engagement: patience, endurance, clear and non-judgmental education, and listening empathetically to the concerns and fears of others. A forced mandate will do none of these things.


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