I listened recently to a podcast conversation between physicians David Katz and Zubin Damania on the ZDoggMD podcast and a few things caught my attention. First, and relevant to this blog, Katz referred to the evolutionary biology of disease a few times during the podcast. Here is Katz on obesity: “We’ve just made that the path of least resistance. Every effort to fix that at the level of the individual basically is opposing the themes laid down by evolutionary biology.” This idea – that society has catered to evolved preferences for fat and refined sugar – is uncontroversial. But Katz goes on to suggest that we should focus more on obesity and nutrition during the pandemic and less on public health restrictions and closures, especially for young people.
Katz describes his medical and public health critics as “completely outraged about SARS-CoV-2 and completely contemptuous and neglectful of other things that actually kill more people.” Katz and other podcasters – I am looking at you Joe Rogan – seem to prefer nutritional strategies over public health efforts aimed at preventing disease (distancing, prohibitions against large groups, and masking). Katz is one of the signatories of the Great Barrington Declaration, whose authors advocate for herd immunity by natural infection. Here is Katz on public health orders: “the extreme moral preening of the left has precipitated the extreme rejectionism on the right. I mean, you’re basically trampling on civil liberties to no gain. There’s no evidence that this is helping anybody and it’s hurting people and restaurants are going out of business.”
Although I am sympathetic to the plight of restaurateurs, public health orders have been effective in my home state of New Mexico, at least to the extent that they have been followed. We have done vastly better than the lassez faire approach taken by our neighbor state Arizona.
Katz continues with this proposal: “Okay, now those of you in the low risk group are willing, let’s have you be back out in the world.” His predicted result: “I’m gonna say that heretical thing, herd immunity has developed in that low-risk group.” Yes, Dr. Katz, “back in the world” is indeed our current de facto situation, in part because of opposition to public health measures. Look what that has gotten us – 353,000+ deaths and counting. No herd immunity. And because those “low risk” people work in nursing homes and have high risk relatives, this approach has been demonstrably lethal. Katz’s idea, popular on the right, focuses exclusively on sheltering vulnerable people, especially in nursing homes. The problem is that it simply has not worked.
The fantasy that slender people 50 and younger can frolic in crowded concerts and parties is a fever-dream with disastrous consequences. As I wrote back in June: “Besides the wrong-headed notion that a huge chunk of the population is considered useless and disposable, vulnerable people can’t just be quarantined on an island to fend for themselves. They necessarily interact with younger caregivers and family members, who would put vulnerable people at even greater risk! And any attempt to separate the “vulnerables” would necessarily concentrate them together, which increases the risk of outbreaks, and provides greater selective pressure for increased virulence.”
This has proven correct. People in long term care facilities are protected when the community levels of infection are low, like in New Zealand. Infections and deaths in long term facilities match the rate of coronavirus infection in the communities where they exist. “We can’t stop the nursing home cases and deaths unless we stop community spread” says health economist Tamara Konetzka, quoted in this CNBC article.
Katz also argues that concerns about COVID-19 in children are overblown and school closures do more harm than good:
“But here’s the risk of your child being injured in a given year if they just commute to and from school in a carpooler school bus. And if the risk of being hurt by the virus is less than their risk of commuting to school, which you let them do every year, maybe you don’t need to freak out about the virus.”
This elides the obvious fact that a child’s COVID-19 infection is fundamentally distinct from a motor vehicle crash, because they can be a link in an exponential transmission chain. While Katz seems uninterested in protecting most children from infection, he bemoans the problem of obesity on COVID-19:
“I’ve spent a career trying to talk people into addressing these chronic liabilities.”
If we followed Katz’s advice – we’d eliminate restrictions on young adults and children (letting them contract the virus) and instead steer children away from junk food. I have no problem with the latter, but I take issue with the former. I’ll explain why:
Previous pandemics offer lessons for these chronic diseases and longevity.
Despite his interest in evolutionary biology, Katz has overlooked an important insight from evolutionary medicine that punctures his main contention. Surviving early life infections is a risk factor for the very same chronic cardiometabolic diseases that Katz is so interested in. Data from earlier pandemics show that some survivors of infection have an increased risk of later deaths from heart attacks. This effect is powerful, outweighing most other risk factors.
Finch and Crimmins showed that men 60-82 years of age who were in utero during the peak 1918 influenza pandemic had the highest risk: ischemic heart disease increased by 32.7%. The excess risk of hypertensive heart disease was 21.6%. Cardiovascular disease by year of birth is shown below.
The Cohort Morbidity hypothesis of Finch and Crimmins describes “new links in the developmental origins of adult health and disease in which effects of early life circumstances, such as exposure to infections or poor nutrition, persist into mid-adulthood and remain evident in the cohort mortality rates from ages 40 to 90.”
Crimmins and Finch have shown that exposure to life threatening infections before the age of 5 is strongly associated with premature cardiovascular mortality, based on cohort data from Sweden and other European countries. Further work extends the vulnerable period from 0 to 14 years of age when exposure to infection might increase the risk of chronic diseases in adulthood.
“Early cohort mortality is assumed to reflect the early life circumstances of children in the cohort, mainly mortality due to infections… ” write Sanchez, Crimmins, and Finch. The mechanism of increased cardiovascular risk may be exposure to chronically higher inflammation, as shown by blood levels of C-reactive protein (CRP), IL-6, and fibrinogen. These inflammatory biomarkers are associated with higher risk of stroke and heart attacks.
Easterlin, Crimmins and Finch have recently applied their framework to the COVID-19 pandemic. They propose a longitudinal framework for measuring cardiovascular outcomes in those exposed to early life COVID-19. While this focuses mostly on those exposed in utero to COVID-19, it is biologically plausible that COVID-19 in childhood might also increase cardiovascular and diabetes risk later in life.
Crimmins and Finch take an evolutionary approach to their research on human longevity and early life causes of chronic adult disease. Interested readers can read about the evolutionary medicine basis for developmental plasticity that might affect later life diabetes and heart disease that we have covered in earlier entries. Related ideas, such as the thrifty phenotype and predictive adaptive response are briefly described here.
Food for thought: Katz should consider that COVID-19 infection in childhood and young adulthood is extremely important to the very outcomes that he has admittedly spent his life’s work on. By preventing young people from getting COVID-19, we can probably prevent future heart attacks, strokes and diabetes.
Joe Alcock MD
Emergency Physician, Educator, Researcher, interested in the microbiome, evolution, and medicine