Comparing the Vaccines

​Kelly Rudd, PharmD.
​Kelly Rudd, PharmD.

We now have three very effective approved vaccines and clinics are giving out thousands of shots a day. This is outstanding!

While moving into this new phase of the pandemic, I hear neighbors and friends trying to process vaccine information to answer important questions: "Are these vaccines safe? How do they differ? Should I try to get one rather than another?"

These are good questions. We each want to make wise medical choices for ourselves and our families. As a pharmacist, I live and breathe this material. I would love to help you by unpacking it a bit.

Safety First

Everyone's first question is whether these vaccines should be trusted.

There's no stronger encouragement I can offer than this: I have been vaccinated and I would encourage anyone I love to get any of the vaccines as soon as they become eligible. I trust the vaccines. My trust is founded in my understanding of the strong and sound science behind them – none of them use the actual COVID-19 virus, so it impossible for you to get infected from them.

Pfizer and Moderna are the first vaccines of their kind approved in our country, but the underlying technology has been used for decades. They contain genetic coding material called messenger RNA (mRNA). This fragment of the coronavirus's mRNA orders your body's cells to produce of a protein that appears on the outside of the coronavirus. These proteins trigger an immune reaction and your body creates antibodies to fight them. If you're exposed to the real virus later, your immune system will recognize the protein and can produce the antibodies to fight it.

At present, both mRNA vaccines require two shots to create full immunity.

Janssen (Johnson & Johnson) is a viral vector vaccine, similar to others we've used for decades. Rather than mRNA, it uses the harmless "adenovirus" as a vehicle to introduce the coronavirus's genetic material to your immune system. The adenovirus inserts the material into your cells to produce the distinctive coronavirus protein, much like the mRNA vaccines. This again creates the coronavirus protein to be shown to your immune system, triggering the immune response that teaches your body to create antibodies.

Johnson & Johnson's viral vector vaccine requires only one shot.

Understanding Effective Rates

The effective rates of the approved vaccines have been the center of attention. They should be — they are high! But I think it's easy to confuse the effective rate with an illness rate. "If Pfizer is 95% effective," many of us assume, "then there is a 5% chance it will make no difference and I will get COVID-19."

That's a natural conclusion to draw — I would probably think the same thing if I didn't work with these rates regularly. But that's not actually how it works.

In a clinical trial, vaccine results are compared to a control group of people who received no actual treatment. Pfizer's effective rate means that 95% fewer people contracted symptomatic COVID-19 in the vaccine group.

In contrast, only 4 out of every 10,000 people who received the vaccine in the trial got symptomatic COVID-19.

Comparing the Vaccines

It is tempting to use effective rates to compare the vaccines. Pfizer's and Moderna's effective rates are 95% and 94.5%, respectively, whereas Johnson & Johnson's (J&J) is 66%. Doesn't this mean it's not as good?

In theory, that seems true. However, it is hard to say what causes the different rates.

Researchers design their trials so that the only differences between a vaccine group and a control group is the vaccine. Then they can assume that the vaccine was responsible for any differences in the results.

But none of the trials have compared the vaccines to each other. J&J in particular was tested in different communities, after new COVID-19 strains had arisen, and when people were responding to the pandemic differently. We can't know how much those factors affected the results.

The Most Important Number

When evaluating the vaccines, there is another number that I believe is given less attention than it should. The effective rates consider how well the vaccines prevent mild or moderate infection. However, all three appear stellar at preventing severe infection. No one who received the vaccine during the trials was hospitalized by COVID-19 and no one died.

The Time Factor

There is another factor influencing people's vaccination decisions: time. "I want 'one and done.' I'll wait for J&J to avoid a second appointment."

I get it — no one likes extra appointments. But consider: We have endured so many inconveniences, sacrifices, and tragedies since last March. Is one final inconvenience worth prolonging this pandemic?

We must act on this opportunity to finally end this pandemic together. Get whichever vaccination you can, whenever you can.


Kelly Rudd, PharmD, is the director of Pharmacy Services for Bassett Healthcare Network. 

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