COVID-19: Answering A Few Common COVID Vaccine Questions

by Raywat Deonandan, PhD
Epidemiologist & Associate Professor
University of Ottawa
(I add my credentials to these COVID-19 blog posts in case they get shared. I want readers to know that my opinion is supposedly an educated and informed one)

Shhh. The baby is asleep, so I have to type this really quietly.

In today’s post, I hope to address a few of the more common questions that both the public and the media have about the new COVID vaccines. As of now, we really only have data for three jabs: the Pfizer/Biontech one, the Moderna one, and the one produced in partnership between Astra Zeneca and Oxford University.

Since conspiracy theories are out of control these days, I must begin with the standard disclaimer. Yes, I have done paid consulting work for drug companies in the distant past. And yes, I own shares in both Pfizer and Astra Zenaca…. amounting to HUNDREDS, yes HUNDREDS, of dollars. Watch out, Jeff Bezos.


Question: If the vaccines only prevent symptoms and don’t stop infection, then what’s the point?

The clinical trials were designed to test whether the vaccines stop symptoms, not whether they slow transmission. So we know the former well, but don’t really know the latter.

To know whether transmission is affected, we have to either wait a few months for the epidemiological data (e.g., reductions in test positive rate once a large proportion of people have received the jab) or conduct immediate special studies (like maybe a challenge trial). At the phenomenal rate at which Israel is inoculating its people, we might get some compelling transmission data from them sooner than expected.

In short, there is a difference between “we don’t have data yet to definitively conclude that it does” vs “it doesn’t”.

However, the Astra Zeneca trials had more testing capacity, so their data show that their vaccine prevents asymptomatic cases, which implies that it does indeed reduce transmission.

And given the huge effect sizes of the the Pfizer and Moderna jabs, combined with promising animal data from earlier trials, I’m willing to bet money that they indeed do reduce or even eliminate transmission, in those in whom the jab was effective (i.e., >90% of recipients, in the case of the mRNA formulations).

Even if they don’t, the fact that they prevent symptoms will reduce transmission at the population level, since symptomatic people tend to spread infection more than asymptomatic ones.

Another perspective is that if the vaccines “only” limit severity, then COVID just becomes another very mild respiratory infection. This may not be great news for those who cannot accept the vaccine, for whatever reason, but if sufficient people become inoculated, the ICUs will not be overrun, and the overall goal of inoculation will still have been achieved: to beat back the public health crisis.


Question: How can I trust a vaccine that was so rushed?

This is a favourite question of mine. I want to throw it back: would you prefer if we waited another four years before we got a vaccine? We should be celebrating, nay we should be down on our knees and thanking the gods of science that this miracle came to us so quickly.

But I get the skepticism. The previous record was a mumps vaccine produced in the 1960s, which took about four years. These COVID vaccines have come to us in under one year.  Here’s how that was accomplished:

1) Pivoting: Scientists were already working on vaccines for things like Ebola and cancer. The labs were supplied and staffed, and funding was established. The “platforms” as they call them were already established. So when the COVID crises came barreling at us, these heroic scientists pivoted to focus on the new threat. Time was thus saved.

2) Headstart: We had already seen MERS and SARS year back. In both those instances, preliminary work had begun on developing a coronavirus vaccine for humans. (Yes, they already exist for some animals). So some of the basic work was already present. This also saved time.

3) New tools: The new technologies –miracles of imagination, really– including the mRNA approach (used by Pfizer and Moderna) and the viral vector approach (used by Astra Zeneca and the Russians) really are groundbreaking. The mRNA technique is particularly powerful, in that the actual vaccine was created just 48 hours after the genome of the virus was sequenced. Just 48 hours. All the subsequent months were spent testing its effects and refining its dosage.

4) Community: The scientific community has been enriching itself with extraordinary capacity –virologists, microbiologists, epidemiologists, data scientists– in both public and private sectors for decades. This is not the same world tha we had in the 1960s. Vaccine discovery could be fast because we had the capacity, in terms of expertise and human resources, to make it fast. The mRNA vaccines could be created quickly only because the capacity existed to produce a genomic sequencing of the SARS-CoV2 virus existed, and because that sequencing was shared globally the instant it was done.

5) Multiple candidates: Bill Gates can probably take credit for this one. He suggested that developers and manufacturers could be encouraged and incentivized to create competitive COVID vaccine candidates in parallel, rather than in series. This way instead of gambling on one or two promising approaches, we could try scores, if not hundreds, all the way to the clinical trial stage. In this way, the probability of getting at least one viable candidate quickly was vastly improved.

6) Money: Probably the single biggest reason we could move so fast was because governments (primarily the US government) underwrote the risk for drug companies. Clinical trials are expensive ordeals, and so few companies are willing to roll the financial dice on low probability or new technologies without great assurances of success. But when there is no financial risk, they are free to explore any technological avenue they wish. In this way, over a hundred candidates could bear half a dozen promising vaccines, all of which received full funding for several very very expensive and thorough clinical trials, resulting in the number of licensed products circulating in the world today.

7) Efficiency: There were no delays. In some cases, phase III trials started before phase II data were completely collected. Some companies started manufacturing doses in the millions well before phase III trials were commenced, in anticipation of a good outcome, so as not to delay putting shots into arms.

8) Regulatory expedience: In many countries, especially the USA and Canada, assessment of the data for licensing purposes was done in real time. This means that every time a data point was collected, regulators could analyze it without having to wait until the whole process was finished before beginning their review process. In this way, government was in a position to render a judgement on the quality of the data the moment that the final clinical trial data were published. No time was wasted scheduling interminable meetings or poring over the details for additional weeks; that had already been done.

9) Large trials: The phase III trials for the leading candidates enrolled tends of thousands of people each. That’s a huge number of people. This allowed each trial to reach its endpoint faster. The trials were concluded when a certain number of COVID positive cases were detected in both the vaccine and placebo arms. If you only had a couple of thousand enrollees, it would take a very long time to reach that endpoint. But having the money –and the eagerness of participants– to recruit about 40,000 people in each trial meant that that endpoint was reached in a matter of weeks, not months or years.

10) High prevalence: Similarly, you can get to the endpoint of a certain number of COVID cases if you run the trial in a high prevalence area where enrollees are more likely to become exposed to the virus. Unfortunately –and fortunately– the pandemic is raging in many parts of the world. As a result, places like Brazil, UK and USA were prime locations for enrolling participants. Those areas’ inability to control transmission served to shorten the length of phase III clinical trials, and got us licensed vaccines in record time!

Note: no short cutes were taken. Nothing that would have been done in a non-pandemic year was missed in these trials. They were conducted just as one would any other clinical trial of this nature. The speed of outcome was due to the ten factors above, and not because anything was “rushed”.


Question: Can the mRNA vaccines change my DNA?

No. No they cannot. This is a horrible bit of misinformation making its way through social media. It’s accelerated by a misinterpretation of a video in with Bill Gates says that maybe we can make a COVID vaccine by editing DNA.  Gates was talking about editing the DNA of a virusSpecifically, we was talking about genetically modifying an adenovirus (a mostly harmless virus) so that it would carry the SARS-Cov2 spike protein on its surface.  This is exactly how the Oxford/Astra Zeneca and Russian Sputnik V vaccines work.

He was not talking about changing the DNA of humans.

Here’s a quick review of high school biology. DNA is the most important molecule in your body. It stores your genetic material: instructions on how to make youIt’s kept in a secure vault in each of your cells, within the cell nucleus. When it comes time to make new things, like a protein, your body unzips the DNA and copies relevant pieces of it onto something called mRNA, or “messenger RNA”.

The DNA gets re-zipped up and put back into safe storage. But the mRNA that was just created makes its way to something called a ribosome, which is a factory in your cell. There, the ribosome reads the content of the mRNA, which is essentially a recipe card, and makes the protein from that recipe.

The sequence of events is:

The mRNA vaccines introduce an external mRNA into this system. As you can see from the diagram, it renders its effect downstream from DNA, so should not be able to interact with your DNA at all. All it does is insert a new recipe card into the ribosome, to tell it to make the infamous “spike protein” that causes an immunogenic reaction:


So no. The mRNA vaccines do not interact with, mess with, or alter your DNA.


Question: I hear the COVID vaccines cause sterility.

Sigh. You know what? Almost all of these claims come from the same handful of people. They claimed that the pandemic is fake because the PCR test creates too many false positives. (It does not). Then they claimed that we reached herd immunity back in May because of something something cross-reactivity something something T-cells. (We did not.) Then they claimed that the mRNA vaccines change your DNA. (It does not). Then they claimed that it causes sterility. (It does not.)

I will not name these people, because I don’t want to give them any public oxygen. But here’s a thought: when you get so many things glaringly wrong, maybe it’s time to stop being listened to?

Okay, on to the false claim.

Those pushing this false narrative make the observation that a protein called syncitin-1 is very similar to the fabled spike protein, the one on the surface of the virus, and which all the vaccines teach your body to attack with antibodies.

Syncitin-1 is found in human placenta. So the claim is that if you produce antibodies against the spike protein, then those antibodies will attack syncitin-1 instead, and ipso facto, suddenly your placenta won’t work properly and you’re effectively sterile.

First, the spike protein and syncitin-1 are barely similar at all. They share a minute quantity of amino acids. So it is exceedingly unlikely than an antibody would mistake one for the other.

But you don’t need to know that to realize that this claim is bogus on its face. You know who makes antibodies against the spike protein? Anyone who has ever been infected with COVID.  According to the CDC, that includes over 50,000 pregnant American women.

If those antibodies really did attack the placenta, there would be an epidemic of miscarriages among those women. Yet that has not happened.

No. COVID vaccines show no evidence of adversely affecting human fertility.


Question: Do the mRNA vaccines contain tissue from aborted fetuses?

No they do not. None of the mRNA vaccines being injected into your body contain anything taken from an aborted fetus, human or otherwise.

This myth does come from a bit of fact, though. And it’s important to be transparent about the nature of this research. Both Pfizer and Moderna did perform what’s called confirmatory tests of the vaccine on fetal cell lines, to make sure that the shots are doing what they’re supposed to do.

Let me say that again: they were tested on fetal cell lines, as in they were injected into a petri dish filled with fetal line cells to observe how the cells respond. The vaccines themselves do not contain anything from those lines.

Also, it’s important to realize what a “cell line” is. A cell line is not taken from an actual fetus. Cell lines are artificially grown in the laboratory, and are descendants of cells taken from fetuses from elective abortions decades ago (40 years or more ago).

If this offends your personal morality, that is your choice and you have a right to those feelings. I’m an over-the-top animal lover and it pains me deeply that non-human animals were harmed and sacrificed in the making and testing of these products. So I understand your discomfort.

But despite my strong beliefs as an animal rights advocate, I will be accepting these vaccines into my arm at first opportunity. Am I a hypocrite or a realist? Possibly both. But transparency is important in science communication. This is how we build trust.

Quoting a document from Nebraska Medicine, it’s important to note that vaccine manufacturers can use fetal cell lines in three roles:

i. Development: Identifying what works
ii. Confirmation: Making sure it works
iii. Production: Manufacturing the formula that works

Neither the Pfizer nor Moderna vaccines used fetal cell lines during the development or production phases. No fetal cell lines were used to manufacture the vaccines. Therefore no fetal tissue is inside the actual injection. However, both companies used a certain fetal cell line in the confirmation phase to ensure that their vaccines work. And, according to one source, all of those cells were descended from tissue taken from a 1973 elective abortion that took place in the Netherlands.

I’m sorry if that makes you uncomfortable. But if we are to benefit from a thing, the least we can do is acknowledge the sources of that thing, and not to look away. Do think about all the animal suffering and death that are required to keep us supplied with our panoply of billions of biologics, both essential and frivolous, and about which most never give a second thought.


Is that all?

Oh no, there are many other questions out there. I will try to get to more of them in a future post.