Natural Immunity…Shh! Don’t Say Those Words!

by: Dr. Eeks

This morning I flipped through a couple of my Epidemiology books from public health school, trying to figure out why “natural immunity” became taboo. I always just assumed that herd immunity included both natural immunity and if there was a vaccine available, vaccine-induced immunity. The two worked together like teammates, at least prior to 2021. In 2021, “natural immunity” became synonymous with the dirty word, “Anti-vax.” It doesn’t make sense, because if doctors way back when didn’t make observations about natural immunity, we wouldn’t have vaccines.

Let’s take it back to the 1700s, during the Smallpox epidemic. People practiced variolation, where they’d take oozing matter from an active sore and scratch it into the skin of an uninfected person. It was a risky practice, but usually they had mild infections, recovered and developed immunity to Smallpox. A country doctor, Dr. John Fewster, practiced variolation on a group of farmers and noticed that they didn’t react at all. This surprised him so he researched the phenomenon further and realized that all the farmers had previously been infected with Cowpox. They got Cowpox, a virus similar to Smallpox, from milking infected cows. It would manifest as pustules on their hands, but not much more. Fewster began sharing his observations with fellow doctors and eventually a young doctor, Edward Jenner, heard about it. He took the information and ran with it and went on to help create the first vaccine, the Smallpox vaccine. I think Jenner’s contribution to public health is the greatest of all time. Not only did it lay the foundation for other life-saving vaccines, but Smallpox had a very high case fatality rate and a reproductive number somewhere between 3.5 and 6. That means that if 1 person got it, he/she could pass it on to 3.5-6 more people, leading to uncontrollable exponential spread. Even when people survived, they had horrific scarring, often on their faces. Relying on “natural immunity” alone or hoping that everyone would go out and milk a cow with Cowpox and become immune that way would have been imprudent.

Pointing out the contribution natural immunity makes towards achieving herd immunity is not the same as being anti-vax. It’s science. That said, I can see how the concept of natural immunity may be misconstrued or used as a buzzword to promote an anti-vaccine message. For example, many health and wellness enthusiasts love buzzwords. Heck, I follow a strict wellness routine and love buzzwords. When I wrote my quirky audiobook parody on the lucrative wellness industry, I included a list of words that companies use to push their products. They include words like “immune-boosting, detoxing, ridding the body of toxins, skinny cleanse, fully body douche, holistic vagina and toxin-free,” many of which sound sacramental. They also love the word “natural.” It sounds organic, unprocessed, positive and inviting. It’s the opposite of artificial, refined, and processed, words used to describe things one doesn’t dare put in his/her body. Now take the words “natural immunity.” Natural immunity has an organic, earthy feel to it and doesn’t sound like something that comes with any negative side effects. It also sounds like something you’re born with, not something that you acquire after fighting a viral or bacterial infection, a concept that can dupe some people. I work in the field of public health and in my experience of talking to hundreds of people who are concerned about vaccines, they rarely express concern for what it takes to develop natural immunity. You need to fight off a virus to develop natural immunity, and that is a gamble. Some people might have an easy fight, but others won’t, and while age and comorbidities should absolutely factor into one’s risk assessment, there are no guarantees. From a health-communications perspective, I think a more accurate way to describe natural immunity is by calling it naturally-acquired immunity. NAI for folks who love acronyms? Or even better, how about vaccine-induced immunity vs virus-induced immunity? For the sake of flow, I’ll use “natural immunity” throughout this piece, but I’m eager to hear suggestions for alternative names, or perhaps you think it’s fine the way it is.

No matter what we call it, there seems to be an orchestrated effort to downplay the significance of natural immunity when it comes to COVID-19. It’s often presented as something risky or dangerous, like a recreational drug laced with fentanyl. People fear that anything positive about natural immunity will sabotage the vaccine effort or encourage deliberate attempts to become infected, like Dennis Prager recently touted on his radio show. Anyone who points out the benefits of natural immunity is automatically labeled an anti-vaxxer even if you’re merely citing published statistics from scientists. It’s painful and illogical. I mean, what about a hard-core researcher who conducts a study on natural immunity vs vaccine-induced immunity and through the scientific method discovers that natural immunity has an edge? Does that make him or her an anti-vaxxer? Should those types of studies be banned or ineligible for publication because they might fuel anti-vaccine movements? Allowing fear or stigma to guide research agendas does not have a good track record.

Is there evidence for the robustness of natural immunity to COVID-19, even studies showing that it is superior to the vaccines? Yes. Are there studies showing that vaccines are superior to folks who recovered from COVID infections? Yes. Are all these studies peer-reviewed? No, many are preprints, and while it might be more prudent to wait for the review process, running with preprints has been a theme throughout the pandemic. Does every study have some kind of limitation? Yes. No one is being forced to find “the winner” here, but an honest presentation of the evidence shouldn’t be a difficult task. Unfortunately, we live in the era of cherry-picked preprints that are used to support preordained agendas and biases. Even the Gods of Truth, who go by Fact Checkers on earth, cherry-pick studies to the point that the Fact Checkers need Fact Checkers. I suggest calling those guys the Depoppycockers: #depoppycocked

What studies support natural immunity?

I will only mention a few, and start with the studies in Israel, since those are the largest ones.

A study by Israel et al conducted a population-based study that compared antibody titer decay in  2,653 fully vaccinated people with no prior history of infection to antibody decay in 4,361 unvaccinated people who recovered from COVID-19. They pulled data on adult members of Leumit Health Services, an HMO that provides service to 700,000 people. Results showed that the vaccinated had higher SARS-CoV-2 antibody titers after the second dose compared to the recovered individuals, but the antibody titers decreased by 40% each month in the vaccinated and just 5% each month for the recovered. At 6 months, 16% of vaccinated individuals had antibody levels below the seropositivity threshold (50 AU/ml) compared to 11% of the recovered individuals at 9 months. Dr. Israel came on the TrialSite News podcast to discuss this study, and you can watch it on the Youtube channel.

A large, retrospective, observational study conducted in Israel compared incidence of COVID infection, symptomatic disease, hospitalizations and death among 3 groups of people pulled from a large health system that treats 26% of the nation: 1) Those with no prior infection who were vaccinated (eligible population = 673,676), 2) Those who recovered from prior infection and were not vaccinated (eligible population = 62,853) and 3) Those who recovered from prior infection and had 1 dose of the Pfizer vaccine (eligible population = 42,099). They first compared data for infections and vaccinations that occurred in January or February of 2021. Results showed that those with no prior infection who were vaccinated had a 13-fold increased risk of infection with the Delta variant compared to those who recovered from a prior infection and weren’t vaccinated. The vaccinated also had a significant increased risk of symptoms. They then compared data for infections that occurred over a wider timeframe (March’20-Feb’21) to those vaccinated in January or February of 2021. In that case, those with no prior infection who were vaccinated had a 6-fold increased risk of infection and a 7-fold increased risk of symptomatic disease. Finally, those who recovered from COVID and received 1 dose of Pfizer had a significant .53-fold decreased risk of infection compared to those who recovered and were not vaccinated.

The Cleveland Clinic conducted a study involving employees of their health system to assess the necessity of vaccination in previously infected individuals. The study started in December of 2020, when vaccination began for health workers, and went for five months. Out of 52238 employees, 53% of 2579 previously infected (1359) remained unvaccinated compared to 41% of 49659 who weren’t previously infected (22777). The cumulative incidence of COVID-19 infection in those who were previously infected and not vaccinated, those previously infected who were vaccinated, and those who weren’t previously infected but vaccinated was zero. There was a steady increase in COVID-19 infections in those who were not previously infected and were also not vaccinated. None of the 1359 unvaccinated people with prior infections got COVID-19 over the 5-month period. The authors concluded that vaccinating those who had recovered would offer little benefit, so they should prioritize the vaccines for the nonimmune. Interestingly, the Cleveland Clinic wrote an “update” for this study in August (the study was published in June) telling people to get vaccinated, no matter if they were recovered or not, a clear shift from the paper’s conclusion. They pointed out that the study was conducted before the rise of the Delta variant and mentioned that the study population was young. But why the update at all? Why not let the study speak for itself? One wonders if political forces pressured them to write the update.

Another study published in Science was conducted by researchers from La Jolla Institute for Immunology looked at immune memory (antibodies, memory B cells, CD8 T Cells and CD4 T Cells) in 188 people who recovered from COVID-19. Results showed that immune memory in 3 cell types remained measurable in over 90% of subjects for at least 5 months.

There are also studies suggesting that natural immunity isn’t superior to vaccine-induced immunity and that natural immunity is unpredictable and varies too much from person to person. I’ll focus on a blog post from Nebraska Medicine, because it was shared widely on social media by people with large followings as evidence for “why natural immunity is not better” than vaccine-induced immunity. They use quotes from an infectious disease expert to support their claim and a CDC-sponsored study published in Emerging Infectious Diseases that showed that out of 72 people who recovered from COVID, or 144 plasma samples, 36% did not have detectable antibodies. They cite a CDC Morbidity and Mortality Weekly Report (MMWR) published in November’20 that showed that out of 156 health care workers infected with COVID-19, 94% had a decline in antibodies 60 days from their initial measurement, and 28% had antibodies below the threshold for positivity. Those with lower baseline antibody levels were much more likely to sero-revert than those with higher levels. They reference another CDC case-control study conducted in Kentucky in May’21-June’21. Researchers evaluated the link between vaccination status and COVID-19 reinfection in people previously infected. Results showed that the unvaccinated had 2.34 times the odds of being reinfected compared to those who were vaccinated. There was no mention of any studies that favored natural immunity over vaccines, sans a link to a doctor’s slide presentation explaining why the large retrospective study out of Israel was faulty. The slides said the study was essentially useless because of selection bias “and” survivorship bias. First, survivorship bias is a kind of selection bias, and selection bias is always an issue with any retrospective study. The slides implied that the results are skewed towards natural immunity, because some people who were unvaccinated may have died from COVID-19 and therefore weren’t accounted for in the study. While possible, would that number have been large enough to throw the entire study? Remember, the study included thousands of data points. The slides also show that the vaccinated population in the study had higher rates of comorbidities, which could skew the results against vaccines. While true, the Israeli authors controlled for underlying health conditions, but the slides presenter implies that they didn’t do a good enough job of it. Either way and strangely enough, the authors of the Nebraska Medicine blog didn’t highlight the potential limitations of the studies they listed in favor of vaccines over natural immunity. For example, there was no mention of selection bias, small sample sizes, that the Kentucky study was a retrospective study too, or the possibility of false positive PCR tests. AP Fact Checkers  took a similar approach when they wrote about natural immunity. They didn’t bother to list or discuss the above-mentioned studies in favor of natural immunity. Why would fact checkers from a large news corporation fail to mention those studies, especially the larger ones out of Israel? That does not make sense if you are truly interested in facts.

There are more studies out there that either support natural immunity or don’t, but it’s safe to say that the evidence base for natural immunity has strengthened over time, not weakened. Therefore, it doesn’t make sense when social media’s blue-check-mark army and the mainstream media wave away natural immunity like it’s just another anti-vax conspiracy theory. It creates distrust among smart folks who think beyond catch phrases and political tribalism and decide to take a closer look at the evolving evidence.

From a policy perspective, and in the midst of wars over vaccine mandates and passports, leaders should reconsider ignoring natural immunity. Diehard vaccine proponents should reconsider it, seeing that a recent Gallup poll showed that the biggest percentage of people choosing not to get vaccinated was because they had COVID-19 and still had antibodies. While I’m not a fan of mandates or vaccine passports and strongly prefer conversations and the creative arts to address public-health concerns, couldn’t we at least consider offering proof of immunity, like a past positive test or antibody titers, as an option? Wouldn’t that make more scientific sense than taking away people’s jobs, their benefits and their ability to feed their families in some cases? Wouldn’t it make more sense than firing qualified healthcare workers and first responders who may have recovered from COVID-19 and don’t want to get vaccinated? Wouldn’t it make more sense than preventing regular people from entering bars, restaurants, salons and gyms? As it stands, some mandates and vaccine passports, like New York City’s vaccine passport policy, only require 1 dose of an mRNA vaccine to enter an establishment, mask free. If we are allowing mask-less, partially-vaccinated people to participate in society, shouldn’t we at least allow those who have recovered to do the same? That would be following the science. What’s happening now feels like torturous arm-twisting. It feels toxic. While I think we are too lazy as a society to look up from our phones, get off social media, out of our chairs and start an actual Civil war over the issue, medical freedom will be a top issue at the ballot box. I just hope we don’t rebound too far in the other direction and make Measles great again.

Unlike medical interventions, public health interventions address issues at the population level, making it nearly impossible to please everyone and difficult to maintain a peaceful equilibrium between individual freedom and the sacrifices people are willing to make for the perceived greater good. For ease of execution, they can sometimes feel like a one-size-fits-all hat that is annoying and constantly needs adjusting. One needs to think about the population’s trust in conventional institutions, political leanings and philosophical beliefs when considering how successful an intervention might be. Once you lose or piss off a solid portion of the population, the intervention won’t work out so well no matter how good it looks on paper. In the case of natural immunity and COVID-19 however, I believe our society is sophisticated enough to recognize its value for the sake of allowing people to work, go to the gym, watch a movie or eat at a restaurant and at least shift us closer to a more viable and nontoxic equilibrium.

Thanks for reading!

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See you around,

Eeks