Can COVID19 Reinfect Us?

Can COVID19 Reinfect Us?

David Katz 03/05/2020 4
Can COVID19 Reinfect Us?

This past weekend, the World Health Organization stoked the flames of global anxiety by issuing this in the guise of a reality check: we do not know that getting COVID19, and recovering from it, results in immunity

The media, naturally, said “thank you” for the rekindled fire, and threw gasoline on it: the story, and its attendant anxiety, were everywhere. As my friend John Tesh reminds me about media, “if it bleeds, it leads.” Sticking with my more flammable version of that sentiment, perhaps we may paraphrase: “if it combusts, it’s among the front-page musts.”

As it happened, I was conferring with Tom Friedman at the time about his latest column for the New York Times. When we spoke on Monday, I made this observation as part of our discussion: “you realize, of course, that if infection itself does not confer immunity, there is just about zero hope that any vaccine could.” 

Somehow, the WHO precaution left the world thinking that since infection may not confer immunity- we’ve got to have a vaccine. But that notion is just about oxymoronic, give or take the “oxy.” Tom asked me to explain why, and here’s that explanation, expanded.

You can think of the immune system as your personal security team, on the job, round the clock, to defend you from dangerous intruders. So, let’s say your front door has been assaulted by some such intruders in broad daylight, faces fully on display. If those same folks turn up again, your security team will recognize them immediately as a threat, and take protective, defensive action accordingly. Forewarned is forearmed when it comes to immunity- and a good look at the threat in question is the priming event for both. In the case of a pathogen, that “good look” comes in the form of an infection.

But what if instead of seeing the assailants, you only got a glimpse, or a narrow view? What if you just saw the back of a head, or the left shoulder, or a silhouette? All of these might help recognize the threat when these folks turn up again- but maybe not. Certainly, you would be less reliably forearmed than if you had seen the threat clearly, and fully.

A vaccine is something like that partial view. Let’s keep this simple, and pretend that there are three kinds of vaccines (there are more, but these three cover the key considerations). The first is made using just a small part of a virus (or other pathogen), i.e., one or more proteins. The second is made using the whole virus, but killing it first. The third is made by “attenuating” the virus without killing it- in other words, beating it up enough so it is too punch-drunk to cause its native harm. 

Each of these is a stand-in for the native pathogen, intended to trigger a defensive response. But as with our perpetrators at the door- they do so with variable reliability. The more like the native infection, the stronger and more reliable the immune trigger. The less like the native infection, the less robust, generally, the immune trigger. Accordingly, the “protein only” vaccine is less potent than the killed pathogen vaccine, which is in turn less potent than the live, attenuated (“punch drunk”) vaccine. And none of these is as potent as…the infection itself.

Measles is a good example. The vaccine (administered in combination, as the MMR) is among the best, because it is a live, attenuated vaccine. But even so, it appears to confer immunity that wanes over some number of years- as opposed to getting the measles, and recovering from it, which appears to confer robust immunity to last a lifetime (at the cost of far greater danger, of course).

This story reverberates through the very invention of “vaccines,” the very reason we call them “vaccines,” which is derived from the Latin word for “cow.” 

Edward Jenner famously recognized that “milkmaids” who had recovered from cow pox were resistant to the far more dangerous small pox. The two were enough alike that exposure to the one primed the immune system to the other. The smallpox vaccine was born. Getting smallpox itself -and recovering from it- likely resulted in even more robust immunity against it, but thank goodness, cowpox exposure proved to be good enough.

There is, of course, more to the vaccine story, and ways to work around roadblocks, involving haptens, and combination vaccines. Those details are beyond the scope of this telling. The general rule prevails: vaccines tend to confer lesser immunity than the infections they prevent. When the infections themselves don’t produce immunity- as is true, for instance, of herpes viruses and HIV- vaccines prove elusive at best, impossible at worst.

I shared this perspective on Monday, and then it showed up in USA Today on Tuesday, courtesy of the chief epidemiologist for Sweden’s public health agency. Deux beaux esprits se rencontrent.

That all explains why the apparent message this past weekend, “we can’t rely on herd immunity, so let’s count on a vaccine,” was intrinsically nonsensical. But there’s good news to append: it was also almost certainly wrong.

The WHO was not saying that we don’t get immunity from COVID19; they were simply saying we don’t have PROOF yet that we do. That’s true. We haven’t yet had time to aggregate data from people who (a) got the infection; (b) got over it; (c) made measurable antibodies to prove they were over it; (d) got re-exposed whether accidentally or on purpose; and then (e) were reassessed for infection. The WHO was not saying we have evidence against immunity; they were simply saying we don’t yet have decisive proof of immunity. 

But, in fact, there is a mass of support for immunity, including animal studies, the apparent pattern of global epidemiology to date, and precedent with a wide range of related pathogens. This was my impression, but I ran it by Dr. Michael Osterholm whose perspective on all this I value greatly- and he concurred.

The WHO announcement, in other words, was simply about absence of evidence. It was played up by the media as if indicating evidence of absence. They are entirely different.

To be clear: there is no evidence against the prospect of herd immunity. And Sweden reports being well on its way.

So, along with the reality check about immunity- I think we need one about the role of media in all this. If it bleeds, it leads – is, indeed, a media aphorism. So is: “comfort the afflicted, afflict the comfortable.” If you are getting comfortable with the idea that herd immunity is the way back to life as we formerly knew it- there’s incentive for the media to afflict it.

Why? Just consider how we all crane our necks driving past a pile up. Morbid fascination seems to be wired into Homo sapien DNA.

In addition, if our comfortable knowledge is forever afflicted, we remain perpetually uncertain, doubtful, and confused. What to do in those circumstances? Tune in tomorrow in the hope of answers. When tomorrow produces new confusion, tune in the next day.

This is familiar terrain. The truth about diet and health hides in plain sight, obscured by media devotion to perpetuating confusion. In America, diet is the leading cause of premature death and chronic disease, and is now an acute risk factor for severe COVID infection into the bargain. Where diet most reliably optimizes immunity, defends acutely against infection, promotes vitality, and defends longitudinally against diverse assaults on years in life and life in years- it is not courtesy of a rogue theory, new fad, or morning show flavor of the week. It tends to be time honored, the heritage-based pattern of many generations.

I am gratified that many people report loving my most recent book, How to Eat, co-authored with Mark Bittman. But I could not help but notice a theme among those who don’t: “there’s nothing new here!” Well…exactly, except the argument that there’s nothing new here! 

The most important news about diet for health is that there is no real news about diet for health. Pick any balanced dietary pattern of real foods that has stood the test of time and you are reliably better off than feeding on any given pop-culture fad. There, we said it. Deal with it.

I very much doubt COVID19 reinfection is much of a threat, and may be no threat at all. All signs suggest the opportunity to devise a safe, data-driven course to the collective protection of herd immunity. That is the all clear that lets grandparents hug their grandchildren once more; that is how we get our lives back.

But the threat of perpetual reinfection with doubt, confusion, and worry- about COVID, or diet- with every news cycle, that’s another matter altogether. That is a clear, constant, and omnipresent danger. Beware, accordingly- and if you can, work on your immunity to it.

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  • Sunil M

    Excellent article

  • Donna Pearson

    We gotta be patient with COVID19

  • Julie Ellis

    IF COVID-19 can reinfect people, then we are screwed

  • Hubert Leon

    Haters gonna hate..... I like your reasoning.....

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David Katz

Healthcare Expert

David L. Katz, MD, MPH, FACPM, FACP, FACLM, is the Founding Director (1998) of Yale University’s Yale-Griffin Prevention Research Center, and former President of the American College of Lifestyle Medicine. He has published roughly 200 scientific articles and textbook chapters, and 15 books to date, including multiple editions of leading textbooks in both preventive medicine, and nutrition. He has made important contributions in the areas of lifestyle interventions for health promotion; nutrient profiling; behavior modification; holistic care; and evidence-based medicine. David earned his BA degree from Dartmouth College (1984); his MD from the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training in Internal Medicine, and Preventive Medicine/Public Health. He is a two-time diplomate of the American Board of Internal Medicine, and a board-certified specialist in Preventive Medicine/Public Health. He has received two Honorary Doctorates.

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