So Much Mistrust About mRNA Vaccines

It’s been a wild ride for mRNA-based vaccines — from the life-saving miracle that got us out of the Covid pandemic to a wellspring of conspiracy theories. Along the way, two negative outcomes have emerged.

First, a politically charged backlash to all things mRNA has made people less likely to take advantage of the annual Covid vaccine boosters that do wonders for keeping us healthier. Covid vaccination rates hovered around 20% during the past respiratory season, a far cry from the uptake we saw during the pandemic. Sadly, partisanship is the biggest factor in the growing refusal to get this valuable protection. Covid boosters are important for preventing serious illness from an infection, and also for reducing the risk of developing chronic symptoms associated with long Covid.

Second, the industry players building an entirely new generation of vaccines and therapies based on mRNA are in jeopardy due to federal funding cuts and the abrupt change in public sentiment. These new treatments aimed to go well beyond Covid — helping with other infectious diseases including bird flu as well as non-infectious diseases such as cancer — but now their path to clinical use is uncertain. The government’s recent cancellation of contracts worth $766 million previously awarded to Moderna is the latest evidence that mRNA vaccine developers are facing serious headwinds.

Given this context, I thought it was time for a quick explainer on mRNA and mRNA-based therapies. (Given that you’re reading Salisbury’s Take, you may already be an expert on mRNA. Consider this a gift you can share with a layperson next time somebody asks you about it.)

What is mRNA?

You probably learned this in high school biology and promptly forgot it, so we’ll start by getting on the same page about this term. Short for messenger RNA, mRNA works as the middleman in our genetic systems: parts of our static DNA blueprint are processed into mission-specific mRNA when needed, and the mRNA dictates which proteins are built to carry out those commands. By its nature, mRNA is ephemeral, lasting only as long as that particular message is needed by the body.

If there’s already mRNA in my body, how can it be used as a vaccine?

Think of each mRNA as an email. (OK, I’m dating myself here. You can think of it as a Bluesky post if you prefer.) Every mRNA produced in your body carries a very specific set of instructions designed for a single task. The mRNA used in Covid and other vaccines was designed to encode its own set of instructions — making a protein that looks like (but definitely is not) a piece of a harmful virus. When this mRNA is injected into our arms, it travels to our cells and tells them to begin producing that protein. Since the protein isn’t something we normally make, our immune system flags it as an invader and mounts a defense against it. Even though the mRNA and the protein it made were both harmless, our bodies now know what the real virus looks like without ever having seen it. If we get infected with Covid after the vaccination, our immune system can recognize the virus and mobilize the defense it already prepared. That’s how mRNA vaccines lead to such effective protection against Covid, flu, and other targets.

What’s the difference between an mRNA vaccine and traditional vaccines?

While there are several different types of vaccines, pre-mRNA types often included some kind of weakened (the medical term is “attenuated”) version of the actual virus. This narrows the pool of people who are eligible for the vaccine, because they are not always safe for people with compromised immune systems such as patients with cancer or organ transplants. No matter how they’re made, the goal of all vaccines is the same: teaching the immune system to recognize a threat so it can take action more quickly when an infection occurs.

How can we be sure mRNA vaccines are safe when they’re so new?

Like any other vaccine on the market, mRNA vaccines have to go through extensive testing to ensure their safety before they’re approved for clinical use. But the amount of data generated about mRNA vaccines goes well beyond what’s typically available from standard clinical studies. Due to the Covid pandemic, hundreds of millions of people received mRNA vaccines after they were approved for use, giving scientists an unprecedented amount of data to evaluate side effects and adverse events. Aside from the known temporary side effects (such as sore arms and flu-like symptoms for a day or two), these vaccines have proven to be very safe. Also, while mRNA vaccines are new to the public, the science behind them has been around for decades.

Couldn’t introducing foreign mRNA into my body through a vaccine change my own DNA?

Nope! Vaccine materials don’t get into the nucleus of a cell, where your DNA is carefully packed and protected. There have been a number of conspiracy theories about mRNA vaccines also containing DNA that can rewrite a person’s DNA, but that’s all they are — conspiracies. There is absolutely no scientific basis for this idea. For more detailed information debunking this myth, check out this blog post or this page from the Centers for Disease Control and Prevention about how mRNA vaccines work.

Looking for more? Check out these recent articles from Salisbury’s Take:

• New Antibiotics on the Horizon, but More Responsible Use Needed

• This Week: Gene Editing in a Baby, 23andMe Acquisition Plans, and More

• Cancer Research Uncovers New Clues to Biological Function

• Genetic Testing Is Being Used More Often. What Does That Mean for Patients?