Is a 7-minute workout just as good as an hour-long bike ride? Yes, it can be.

Let’s face it, most of us don’t really like working out. Yes, there are those who are exercise fanatics, who go on and on about the “endorphin high” they get from a long run or bike ride, but these people are exceptions.

And yet it’s indisputable that regular exercise carries a host of health benefits, not only to your heart and cardiovascular system, but also to strength, mood, and overall energy levels. Exercise is just really good for you.

If you’re lucky enough to enjoy a sport that you can play regularly, you might get all the exercise you need without working out. But most members of modern societies simply don’t. Most humans seem to prefer a sedentary lifestyle.

To make up for sitting around most of the time, many people try to work out regularly. The question is, how long do you need to work out get those cardiovascular benefits?

Not very long, it turns out. That’s good news for those who don’t have time for hour-long workouts.

18 minutes is just as good as one hour. Let’s go back to 2005, when a study out of Canada, led by Martin Gibala at McMaster University, showed that very short, intense exercise–pedalling as fast as possible on on a stationary bicycle–was remarkably beneficial, even better than an hour-long bike ride. In just two weeks, the subjects of this study, who were all young and healthy, “increased muscle oxidative potential and doubled endurance capacity.”

You’re probably thinking, what do I need to do?

Well, for this routine, you need three 18-minute sessions per week. In each session, you do the following:

  1. Exercise as hard as possible for just 30 seconds. On a stationary bike, this means you’ll pedal as fast as you can.
  2. Followed this by a 4-minute rest period where you keep pedaling at a relaxed pace.
  3. Repeat this 4 times, which will take a total of 18 minutes.

Voila! You are done. If you don’t have a stationary bike, but you can use another indoor exercise machine with equal effect (treadmill, elliptical, rowing, etc.) as long as it provides an aerobic workout.

You might have noticed that this is really just a 2-minute workout, in four separate 30-second bursts. But the 4-minute rest periods are important, so you need to plan for 18 minutes, and repeat this 3 times a week.

7 minutes is just as good as 45 minutes. Can we get benefits from an even shorter workout? Yes! A 2016 study by the same lab (Martin Gibala and his students) looked at the benefits of exercising all-out for just 20 seconds, with a short rest period in between, They found that a 7-minute sessions of “sprint interval training” (SIT) was just as beneficial as a 45-minute workout.

Again, you may be asking, what do I need to do for this routine?

For this routine, you use an exercise bike and do this:

  1. Pedal furiously (all-out) for 20 seconds.
  2. Follow this by 2 minutes of pedaling at a normal rate.
  3. Repeat this 3 times, for a total of 7 minutes of exercise.

Repeat the whole routine 3 times a week.

(In the scientific study, the all-out phase used a machine that measured power at 500W, and the slower pace was at 50W. Some indoor exercise machines let you measure your output, but you’re not doing a science experiment here. Just pedal as fast as possible for 20 seconds, and you’ll reap most of the benefits.)

One small caveat here is that the routine used by the scientists added a 2-minute warmup and a 3-minute cool-down at a normal pace. So if you want to follow their protocol more precisely, you’ll need 12 minutes. Still, at 12 minutes this is much shorter than the 18-minute routine above.

How about 4-seconds? Okay, now we’re getting a bit ridiculous, right? But an even more recent study, just last year, looked at the benefits of 4-second high-intensity training, with just a 15-second rest period.

Of course, it wasn’t just 4 seconds of exercise. The subjects of this very small study (11 people, averaging 21 years old) at the University of Texas did 30 repetitions of 4 seconds each. More specifically, they “were asked to cycle as hard and as fast as possible for 4 seconds” on a specially equipped exercise bike. After a 30-second recovery, they did it again.

Repeating this 30 times takes about 17 minutes, but over the course of 8 weeks, the experimenters reduced the rest period to just 15 seconds, which reduced the overall session to less than 10 minutes. However, that’s not likely to work for most people, unless you’re a very fit 21-year-old. So I’m going to call this a 17-minute workout.

Repeating this routine 3 times per week produced benefits in both strength and aerobic capacity, much like the SIT training sessions in the Canadian studies.

So how do you do this “4-second workout” (which really takes 17 minutes)? Here it is:

  1. Pedal furiously for 4 seconds.
  2. Rest for 30 seconds, pedaling at a relaxed rate.
  3. Repeat 30 times.

All three of these workouts I’ve described here can produce cardiovascular benefits equal to a 45-minute bike ride, and they only take 18 minutes, 12 minutes (7 minutes plus warmup and cool down), and 17 minutes.

The only downside of all these high-intensity workouts is that you might sweat, which means you’ll need to shower off afterwards. Another option (not backed up by such precise scientific studies) is a less-vigorous but even shorter 6-minute workout, like this one in the New York Times, which needs no equipment at all and should provide health benefits without working up a sweat. You can even do that one at the office.

So if you don’t have an hour to spare 3 times per week, how about 12 minutes? It can’t hurt to try.

Four reasons why approving the new Alzheimer's drug was a disaster

A few months ago, the FDA approved a new drug, aducamumab, to treat Alzheimer’s disease. This was the first time in 20 years that the FDA approved a drug for Alzheimer’s, and while that may sound hopeful, many experts have already pointed out that it was a colossal mistake, and a looming tragedy for Alzheimer’s patients. Here are 4 reasons why the approval of aducamumab (also called Aduhelm) is such a disaster.

1. The new drug just doesn’t work. The biggest problem is that Aduhelm doesn’t slow down or reverse the progress of Alzheimer’s. More than a year ago, I wrote about the failure of two trials of aducamumab. The two trials, designed to be identical to one another, were halted in March 2019 by the drugmaker, Biogen, due to a “futility analysis” that showed it just wasn’t working.

In other words, there was no point in continuing the trials. So Biogen halted them.

But then Biogen tried to rescue the drug. In what can only be described as torturing the data to try to find a result that they really, really wanted, they went back and looked at a subset of patients in one of the two trials, called EMERGE, and claimed that the higher-dose patients actually did get a benefit.

But the patients didn’t benefit. All that Biogen could argue was that some patients had lower levels of amyloid plaques in their brains. An independent group of scientists also looked again at Biogen’s data, and published a report saying that their analysis still didn’t support any benefit for patients.

It’s true that plaques do indeed accumulate in the brains of Alzheimer’s patients, and aducamumab does seem to reduce plaques. However, despite 30 years of research, no one has been able to show that reducing these plaques has any effect on the progress of the disease.

More to the point, the two trials run by Biogen, which measured clinical signs of disease, found that aducamumab didn’t affect the patient’s illnesses. It didn’t slow down or reverse the inevitable course of Alzheimer’s disease.

The FDA’s own outside panel of experts evaluated the evidence and strongly rejected aducamumab. (10 of 11 voted to reject it, and one panelist was uncertain.) The panel found that not only was there no clinical benefit, there was also a significant risk of harm, including dangerous swelling in the brain. About one-third of patients experienced these risks, and 10% of patients had to stop treatment because of adverse side effects.

And yet in July of 2021, in a nearly unprecedented action, the FDA approved the new drug. Three of the committee members resigned in protest.

Somehow, Biogen convinced the FDA to approve aducamumab based on the drug’s effect on a surrogate endpoint: the level of amyloid plaque in the brain. One could argue that this is similar to approving statins based on their effect on cholesterol levels: by reducing cholesterol, we can reduce the risk of heart disease. The analogy might be apt, but there’s a huge difference: we have data showing that lowering cholesterol does indeed reduce the risk of heart disease. In contrast, despite decades of study, we still don’t have any data showing that reducing the levels of amyloid plaques slows down or reverses Alzheimer’s.

2. A failed hypothesis. This leads to the second reason why the FDA’s action is such a disaster. For 30 years now, the Alzheimer’s community has pursued the “amyloid hypothesis,” which asserts that the buildup of amyloid plaques in the brain is the primary cause of Alzheimer’s. This was considered a huge breakthrough when John Hardy first proposed it back in 1991, and hundreds (perhaps thousands) of papers have been published since that time, exploring this hypothesis.

Over 100 drugs have been developed and tested for their ability to reduce plaques, and some of them (like aducamumab) do indeed reduce plaque levels. Unfortunately, none of them slowed down the course of the disease, so they never obtained FDA approval.

After 30 years of effort, it’s clearly time to recognize that the amyloid hypothesis is a failure. And yet the Alzheimer’s research community continues to cling to it, despite all the evidence that targeting plaques simply doesn’t work to treat the disease.

The FDA’s approval, over the objection of its own experts and a big outcry from the biomedical research community, will only breathe new life into this failed hypothesis. Even more unfortunate is that, by approving a treatment based on a surrogate endpoint, the FDA is now encouraging drugmakers to keep focusing on plaques, which will starve any efforts to find other causes–and other potential treatments–for this devastating disease.

This leads me to the third reason why the FDA’s approval of aducamumab is a disaster.

3. Greed wins. Why did Biogen work so hard to find some shred of evidence that they could use to convince the FDA to approve their new drug? The answer can be found in the price that Biogen set for the drug: $56,000 per year. As the editors of JAMA Internal Medicine have pointed out, if even one-sixth of Alzheimer’s patients in the U.S. alone were to take this drug, the annual cost would be $57 billion, which is far greater than the cost of all Medicare part B drugs combined in 2018.

In other words, aducamumab’s costs could bankrupt Medicare. Or to put it another way, Biogen doesn’t seem to care if Medicare goes bankrupt, as long as they can grab some massive profits.

What is still mysterious is why the FDA decided to overrule its own advisors. The FDA’s defense seems to be that they will require Biogen to continue collecting data “to verify the drug’s clinical benefit.” But they are giving Biogen 8 years to collect this data. That’s 8 years during which Biogen will reap massive profits, Medicare might collapse under the strain, and Alzheimer’s patients will continue to suffer.

In October, the FDA announced an investigation of its own approval process for Aduhelm. This seems rather bizarre: if the FDA suspects there was “improper contact” between Biogen and its own internal staff, then it should simply withdraw approval for the drug until the investigation is complete.

4. This whole affair is taking cruel advantage of a vulnerable, desperate group of patients. Finally, perhaps the worst aspect of this whole fiasco is how cruel it is to Alzheimer’s patients. As Dr. Jason Karlawish explained in JAMA Neurology, even though he disagrees with the FDA’s decision to approve this drug:

I must preserve and protect each patients’ autonomy. One way I do this is by being teacher to patients and their caregivers so they can make choices about how to live well with this disease. I cannot deny them the choices the health care system gives them. Aducanumab is now a choice.

Karlawish goes on to write that he will explain to patients that the benefits are uncertain, and the risks of brain swelling and other bad side effects are very real. But if the patients choose to try it, he will reluctantly prescribe Aduhelm.

We don’t have any effective treatment for Alzheimer’s, and it is a devastating illness. Patients and their families are likely to be desperate, and the mere fact of FDA approval will give them hope. I’ve no doubt that many will want to try Aduhelm, despite the risks. Giving them false hope is simply cruel.

And don’t forget that Biogen halted its own trials of Aduhelm due to “futility.”

The FDA made a huge mistake in overruling its expert panel and approving an Alzheimer’s drug that just doesn’t seem to work, that is outrageously costly, and that might cause serious harm to some patients. Let’s hope that this decision can be reversed. The world needs a safe and effective treatment for Alzheimer’s, and for now, we simply don’t have one.

The 5 Stages of Anti-Vax Angst: A guide

Last week the Biden administration was criticized for making some harsh statements about those who refuse to be vaccinated. “For the unvaccinated, we are looking at a winter of severe illness and death — for themselves, their families and the hospitals they'll soon overwhelm. But there's good news: If you're vaccinated and you have your booster shot, you're protected from severe illness and death,” said Biden.

That statement came in for much criticism on social media, especially by those who took the statement out of context. “You’re not going to convince anyone to get vaccinated with such harsh language,” some scientists complained.

Well, true. But as someone who’s been fighting the anti-vaxxers for years, I recognized the Biden team’s statements as Stage 3 of what I’m calling the Five Stages of Anti-Vax Angst. I understand their frustration, because I’ve been there myself. Let’s go through these stages, shall we?

Stage 1: Disbelief. I first encountered the anti-vax movement, in the early 2000s, when I was leading a research project on sequencing the flu virus (here’s one of our papers), and a reporter asked me, quite seriously, if the flu vaccine could cause autism. Huh? I thought. “Well no,” I reassured him, “where’d you get that idea?” I soon traced the source of his concern back to a now-notorious Lancet paper by Andrew Wakefield, which turned out to be fraudulent and was eventually retracted.

Surely, I thought, the solution is simply to educate people better, and to explain that vaccines are the single greatest medical advance in the history of medicine. With better education, the anti-vax movement will quickly fade.

In Stage 1, vaccine advocates simply can’t believe that significant numbers of people believe stuff about vaccines that simply isn’t true. Alas, though, they do.

Stage 2: Frustration. Unfortunately, merely writing articles explaining the benefits of vaccines is not nearly enough. Officialdom (government agencies like the CDC and NIH) constantly issues statements about the benefits and safety of vaccines, such as this CDC website. Scientists and physicians have written hundreds of articles and countless books explaining how beneficial vaccines are, to no avail. For example, renowned vaccine expert Paul Offit wrote an outstanding book warning of the dangers posed by the anti-vaccine movement, called “Deadly Choices: How the Anti-Vaccine Movement Threatens Us All.” That book appeared all the way back in 2010, and yet look where we are now.

Just a year after Offit’s book, journalist Seth Mnookin published “The Panic Virus,” an excellent exposé of the fraud behind Wakefield’s original paper, and on how the anti-vax movement has been aided (often unwittingly) by popular media personalities.

What these books and others reveal is that the anti-vaccine movement is loud, committed, and (unfortunately) highly influential. For every article or book written by a clear-headed vaccine advocate (and there are many!), there are multiple articles and books promoting wildly inaccurate claims that vaccines cause harm. Trying to refute these claims is like playing whack-a-mole.

Scientific bloggers have learned that no amount of patient explanation can get through to some people, and the anti-vaxxers just won’t quit. Eventually, some of them move on to Stage 3.

Stage 3: Anger. This is where the Biden administration finds itself. After months or years of explaining, pleading, and even begging people to get vaccinated, the crazy, irrational, and often angry opposition of anti-vaxxers (or the “vaccine hesitant,” to use a kinder term) can be just too much.

Some people take a long time to reach this stage. Dr. Anthony Fauci, director of NIH’s infectious disease institute (NIAID), has been the public face of the government effort to get people vaccinated for all of the past year. He’s been subjected to inexcusable vitriol, including death threats towards him and his family, and he continues to try to convince people that vaccines are safe and effective. It’s a tough and thankless job. Dr. Peter Hotez, a vaccine expert at Baylor College of Medicine, has been tirelessly explaining the benefits of vaccines throughout the pandemic, and he too has been subjected to awful, hateful attacks. (Dr. Hotez also wrote a highly personal book a few years ago, explaining why vaccines didn’t cause his daughter’s autism.)

Neither Dr. Fauci nor Dr. Hotez has reached Stage 3, but I wouldn’t blame them if they did. Some public-health experts have, though, and one can see why: after trying for months to get people to do something that reduces their own risk of deadly disease, only to meet defiance, one might say “I’m done. You all can just go ahead and get sick.”

Or, as the FDA’s Twitter account responded in exasperation a few months ago, to the never-ending insistence that ivermectin, can cure Covid-19: “You are not a horse. You are not a cow. Seriously, y'all. Stop it.” (Ivermectin is a de-worming agent for horses. It does not work against any virus, including the one that causes Covid-19.)

The comments on Twitter can be far, far harsher. So when Biden warned that the unvaccinated “are looking at a winter of severe illness and death,” I can’t blame him. After all, he’s right.

Stage 4. Persistence. For those who get past Stage 3 (or skip it entirely), there’s a realization that even though some anti-vaxxers are simply beyond reasoning with (I’m looking at you, Robert F. Kennedy Jr. and Joseph Mercola), that doesn’t mean we can’t fight back. We have to recognize that misinformation is out there, and that some people will continue to spread it no matter what we might say. But there are strategies that work to convince others to get vaccinated, and we have to keep trying. That’s persistence.

For example, a study early this year showed that just a dozen people were responsible for a large majority of the vaccine misinformation across most of social media, including Facebook, Twitter, YouTube, and Instagram. I and others have called for social media companies to de-platform these harmful individuals, which could go a long way towards slowing down anti-vax propaganda. Let’s keep trying.

Another strategy, illustrated by Paul Offit’s 2010 book, is to reveal how anti-vaxxers often profit from their misinformation. Some anti-vaxxers have gotten wealthy selling supplements and “alternative” medicines, promoting them with bogus claims that the supplements can substitute for vaccines. If we raise awareness that these quacks are profiting from the spread of misinformation, that can help raise skepticism about their claims. Getting someone to ask questions themselves–to think critically, in other words–is often the best way to get them to reject the arguments of anti-vaxxers.

And even though I might seem critical of the efforts by government agencies to educate the public, I still think they should do it. Indeed, they should do far more than they are doing: in addition to providing facts about vaccine safety and effectiveness, the CDC and NIH could work harder to directly counter the myths and misinformation that are constantly circulating.

I’ve been blogging about the anti-vax movement since 2008, even before I started writing for Forbes in 2010 (see here and here, for example). I’ve long ago lost count of how many articles I’ve written, trying to point out the harm caused by anti-vaccine misinformation, and I’ll keep trying. So I’d say I’m still in Stage 4.

Stage 5. Surrender. In the face of stubborn opposition, and sometimes virulent and personal attacks, some people eventually just give up. It’s easier, of course, to stop fighting people who just don’t want your help, and I can’t blame anyone who does. When I call this stage “surrender,” I don’t mean to suggest that pro-vaccination and pro-science advocates ever accept the wildly misinformed views of the anti-vaccine movement. Of course not. It’s just that some people decide they can no longer spend time on what seems an endless battle.

I’m not advocating that we should ever give up. We can’t, because infectious diseases don’t care if we stop vaccinating ourselves.

So those are the 5 stages of anti-vax angst, as experienced by countless medical and scientific professionals who are fighting misinformation.

And here we are, in the midst of another huge peak in Covid-19 infections, with a significant portion of the U.S.–and of other countries as well–refusing to get vaccinated. The unvaccinated may indeed be facing a “winter of severe illness and death,” even though no one wants that. I don’t blame anyone for pointing out what is very likely to happen. And if the winter ahead is indeed bad, then I place much of the blame on a small number of very loud voices, such as the Disinformation Dozen, who irresponsibly continue to promote harmful untruths about vaccines.

Vaccines are the single greatest public health advance in the history of medicine. Vaccines have eliminated smallpox from the planet, nearly eliminated polio, and made many other previously-feared childhood illnesses a thing of the past. We can do the same to Covid-19, if everyone will just get vaccinated.

DNA is safe to eat. RNA isn't bad either.

Have you eaten any DNA lately? My bet is that you’ve eaten lots of it. DNA is not only safe to eat, it’s present in many truly delicious foods.

For example, chocolate has loads of DNA. Ice cream also has DNA, plenty of it. And lest you think DNA is only in desserts, it’s also found in hamburgers, cheese, bread, all kinds of sushi, and a very long list of other foods. Want to know which foods are DNA-free? Keep reading.

(Aside: why am I explaining that DNA is safe? Scientists reading this might say of course it is, what’s the big deal? If you’re among those, you don’t need to read any further. But many people are afraid to eat DNA because they don’t know what it is, and the name sounds a bit scary. In fact, a study in 2016 found that 80% of Americans thought that foods containing DNA should have a warning label.)

DNA contributes pretty much nothing to the taste of your food, which is sort of obvious given that it’s found in so many different-tasting foods. That’s because flavors are a very complex combination of many, many ingredients, and DNA is just one small part of most foods. If you were to purify DNA and taste it all by itself, it would taste slightly salty. If you want to watch someone trying this for himself, check out this video:

So how do we know that DNA is present in so many different foods? The explanation goes like this: all living things–plants, animals, fungi, bacteria, and others–are composed of cells. Almost every cell in a plant or animal contains a copy of its genetic code, and that code is captured by DNA molecules. Think of DNA as a very, very long string of chemicals, or “bases.”

In rice, to choose just one example, each cell contains 12 chromosomes, and each chromosome is a long DNA molecule. The DNA strings in rice add up to about 430 million bases. So when you’re eating rice, you’re eating all of this DNA in every bite.

The wheat we use to make bread has even more DNA: every cell has about 16 billion bases. That’s 5 times more DNA than human cells have! But interestingly, the wheat we use to make pasta, called semolina or durum wheat, has only about two-thirds as much DNA as bread wheat (and only 14 chromosomes instead of 21). But I digress.

Thus any food that is derived from a plant or animal is almost certain to contain DNA, unless the food is processed so much that every cell from the original plant is removed or pulverized to bits, and the DNA is somehow removed (which normal food processing or cooking does not do). There’s no reason to remove the DNA, though, because it’s completely safe.

Pretty much every food that has DNA in it will also have RNA. RNA is safe to eat too! Some people have been concerned lately about RNA, which has been in the news frequently because it is used in two of the most effective Covid-19 vaccines, the ones from Pfizer/BioNTech and Moderna. Of course, injecting RNA into your arm is different from eating it, but both are very safe. (For more about RNA vaccines, see the article I wrote just a month ago, here.)

Now let’s answer a question I posed at the top: what foods don’t have DNA? The list is remarkably short:

  1. Salt
  2. Sugar*

Yep, that’s it. Salt is a mineral, so it doesn’t come from living things. And sugar is a simple molecule, C12H22O11, produced by plants such as sugar cane and sugar beets. The asterisk (*) next to sugar is there because unless the sugar is very pure, some DNA from the original plants is probably present, so even "pure" sugar might not be DNA-free.

And if you want to wash down that salt and sugar with a DNA-free drink, you can’t use coffee, tea, wine, beer, or fruit juice. All of them contain DNA.

Before I close, I should add that DNA stands for deoxyribonucleic acid. To some, the name is cause for concern: after all, “acid” can’t be good, right? Maybe we should call it “nuclein” instead; that was the name given to it by Friedrich Miescher, the Swiss scientist who first discovered DNA, in 1871.

Bottom line: DNA is in almost everything you eat, you’ve been eating it all your life, and there’s nothing to worry about.

No, the COVID-19 vaccine doesn't change your DNA. But it does make some long term changes. And that's a good thing.

Cartoon by: Maki Naro, from

One of the common tropes among anti-vaxxers lately is that the Covid-19 vaccine “changes your DNA.” Oh, the horrors!

Do they even know what they mean by that? Almost certainly not. Anti-vaxxers generally have no idea how biology works; often they are so confused that I’m tempted to say they are not even wrong. Even when they are right about something, it’s for the wrong reasons.

Many articles have already been posted explaining that the vaccine can’t alter your DNA, including a wildly popular piece at Forbes and explainers by the CDC and UNICEF.

So let’s dig into this strange notion that the vaccine changes your DNA. First, let’s look at what the CDC has to say:

“Will a COVID-19 vaccine alter my DNA? No. COVID-19 vaccines do not change or interact with your DNA in any way. Both mRNA and viral vector COVID-19 vaccines deliver instructions (genetic material) to our cells to start building protection against the virus that causes COVID-19. However, the material never enters the nucleus of the cell, which is where our DNA is kept.”

I see what they’re getting at here. They’re partly right, but in an attempt to give a simple “no” answer, the CDC got it wrong. It’s true that Covid-19 vaccines don’t directly alter your DNA, and it’s true that they don’t invade the cell nucleus, where your DNA resides. But that’s not the full story.

(The UNICEF article is more accurate and more nuanced, writing instead that “the information regarding harmful effects of the vaccine against COVID-19 on human DNA is unfounded and untrue.”)

Remember that the whole point of a vaccine is to prevent future infections. That means that something in your body has to change, right? So what is different?

Okay, take a deep breath and we’ll dive in. Whenever your body is invaded by a foreign cell–whether it’s a bacteria, a virus, a fungus, or some other pathogen–your immune system starts selecting from among millions of specialized proteins called antibodies, each one a little different. The way it does this is really rather extraordinary: many little pieces of your DNA are cut and pasted together, in millions of combinations, each making a different antibody. Eventually, one of these antibodies “recognizes” the pathogen (by binding to it).

What’s even more amazing is that the successful antibodies are “remembered” by the immune system, in the form of special cells called B-cells that have slightly different DNA! The DNA in these B-cells encodes just the right antibody to recognize the invader–the Covid-19 virus, that is. Once you recover from the infection, some of those immune cells (B-cells and T-cells–it's complicated) persist in your lymph nodes, constantly looking for any reappearance of the virus.

Or, as Ed Yong more colorfully explained:

“Picture the lymph nodes as bars full of grizzled T-cell mercenaries, each of which has just one type of target they’re prepared to fight. The messenger cell bursts in with a grainy photo, showing it to each mercenary in turn, asking: Is this your guy? When a match is found, the relevant merc arms up and clones itself into an entire battalion, which marches off to the airways.”

(For a deeper dive into how the immune system works, see Ed Yong’s feature article on this topic in The Atlantic from August 2020.)

The DNA in these special "memory B-cells is a little bit different from the DNA in all of your other cells. The vaccine itself doesn't stay around, but it "shows" the immune system a few copies of the spike protein from SARS-CoV-2, the Covid-19 virus, and the immune system remembers. And, I should note, a similar change to your DNA happens if you’re infected by the Covid-19 virus itself.

But B-cells are just a tiny, tiny portion of your body. Every other cell type, from skin to heart to lungs to brain, is completely unaffected by the vaccine. And if we didn’t have any way of “remembering” how to fight off infections, then we’d never become immune to anything, in which case the human race would quickly go extinct.

Finally, let me mention one other bit of misinformation. Early in the pandemic, some very well-known biologists at MIT published a paper claiming that the SARS-CoV-2 virus could, through an elaborate and highly implausible mechanism, integrate into the DNA of cells that were infected. This would indeed be worrisome! Many others quickly pointed out that this result could also be explained by more mundane mechanisms (experimental artifacts, essentially), and in the subsequent year and a half, with hundreds of millions of infections, no one has reported a single case where the virus actually did this. So not only is this event (reverse transcription of viral RNA into a human genome) really, really implausible, it also doesn’t even apply to vaccines, which only contain a small fragment of the viral mRNA.

(As an aside, that study by the MIT biologists was highly irresponsible. They were basically showing off their technical skills, saying “look what we can get the virus to do!” without considering how their work might be twisted, once anti-vaxxers got their hands on it. And the CDC response that I quoted above appears to be a direct response to misinterpretations of the MIT study.)

So back to our original question: does the Covid-19 vaccine change your DNA? Not directly, no. But yes, thanks to your own immune system, the overall mixture of DNA in your body is a tiny bit altered after you get any vaccine. Your DNA is also changed every time you recover from an infection, including the common cold. But the only change is in the DNA of a tiny number of immune cells, which hang around as guardians against future infections. And that’s a good thing.