Are vaccines driving the emergence of “escape mutant” variants of COVID-19?

I was perusing the in box of my account for this blog last week, when I came across a bit of what I like to call “fan mail”. No, this wasn’t hate mail (which is what a lot of my “fan mail” consists of), but rather an email of the “Won’t you reconsider what you wrote about a crank?” variety. The crank is Geert Vanden Bossche, whom I first wrote about in March in the context of an open letter by him that had gone viral warning of global catastrophe if the mass vaccination campaign against COVID-19 were not stopped. The reason for his warning was a prediction that mass vaccination would select for more dangerous variants of SARS-CoV-2, the virus that causes COVID-19. This led a reader (whose name I will not reveal) to ask me whether, in light of the much more transmissible (and possibly more virulent) Delta variant that’s been spreading across the US like proverbial wildfire over the last few of months, I might want to “reconsider” my previous criticism of Vanden Bossche:

I just saw an MSN article about how doctors are terrified of what is coming…I wonder if perhaps you would reconsider your critique of Geert Vanden Bossche. He seems to have been prescient, even if the causes are not exactly as he had predicted. The media loves to call this a “pandemic of the unvaccinated,” but other countries have noted a high percentage of “cases” among the vaccinated, while the CDC found that in the Cape Cod incident, 75% of the infected were vaccinated, and, that they were just as likely to transmit the virus as the not vaccinated. If the idea that the vaccinated have very mild illness is true, they are much more probable to spread the illness. For example, they may not recognize their mild symptoms as COVID, and not consider that they, being vaccinated, are able to contract and spread it.

It is also a bit facile that you characterize Vanden Bossche as “anti vaxx.” This epithet seems to be tossed around at anyone who doesn’t suddenly rush out and take the mRNA vaccines. As well, the terms “conspiracy theorist” and “disinformation” get thrown around quite a bit, as if any debate or dissension from the media narrative is either gravely deluded, or perhaps even malicious.

This particular reader cited an article published on the conspiracy website ZeroHedge titled ‘Vaccine Expert Vanden Bossche Calls For “Immediate Halt” To Vaccinations, Says They Encourage “Escape Mutant” Variants‘. Included in that article are two interviews with Vanden Bossche, one by Dr. Chris Martenson for the Peak Prosperity vlog, titled “Vaccines: Awesome Ingenuity or A Huge Mistake?”:

And, of course, Bret Weinstein’s Dark Horse Podcast:

I note that evolutionary biologist turned COVID-19 contrarian and conspiracy theorist Bret Weinstein has been featured on SBM before, mainly for his promotion of the unproven anti-worm drug ivermectin as a miracle cure for COVID-19 based on very bad science and a massive misunderstanding of meta-analyses. I’m not going to go into the weeds of these podcasts so much, given that the viral ZeroHedge article that has been spreading around social media like a proverbial Delta variant of COVID-19 misinformation is much newer than either of those podcasts and links to a blog post by Vanden Bossche (ominously titled “C-19 Pandemia: Quo vadis, homo sapiens?”) that contains his latest arguments.

Before I get into the question of whether “Vanden Bossche was right” or not, first let me point out that I don’t use the terms “antivaxxer” and “conspiracy theorist” lightly. I only use them when the person being described is definitely spreading antivaccine pseudoscience and conspiracy theories, and I believe I documented quite thoroughly that Vanden Bossche was doing exactly that in his letter. Let’s just put it this way. When your prediction of “global catastrophe” to COVID-19 mass vaccination invokes almost exactly the same argument that the godfather of the modern antivaccine movement, Andrew Wakefield, used a mere three months before the reports of an outbreak of a novel coronavirus disease in Wuhan, China regarding measles and the MMR vaccine, you are antivaccine. Sure, Vanden Bossche adapted Wakefield’s arguments to the specifics of COVID-19 vaccination, but at its heart his was basically the same argument that Wakefield had made, that mass vaccination would drive the evolution of new variants of the virus being vaccinated against so that it would become more deadly and better able to evade a vaccine-acquired immune response. Indeed, as I described not long after he had published his article in the house journal of the Association of American Physicians and Surgeons (AAPS), Wakefield took his prediction to a ridiculous extreme, predicting a mass extinction of—you guessed it—humans due to ever more deadly measles variants selected for by mass MMR vaccination. Vanden Bossche predicted basically the same thing due to COVID-19 vaccination, even citing some of the same examples as Wakefield. Let’s just put it this way. When your message is approvingly embraced by antivaccine propagandists like Del Bigtree, either you yourself are antivaccine or you should really take it to heart that antivaxxers love you and rethink your arguments.

In fairness, one does have to acknowledge the difference in situations. The measles vaccine has been around since the early 1960s and the current MMR since the 1970s. In the US, 90%+ of children are vaccinated against measles, and we’ve been vaccinating against measles since the 1960s, with nary a hint of the emergence of deadly variants. So of course, Andrew Wakefield’s fear mongering was, on its face, easily identifiable as ridiculous. In the case of COVID-19, which hit Wuhan seemingly out of nowhere in late 2019 and was declared a pandemic by the World Health Organization (WHO) a mere three months later, in March 2020, the question of whether vaccination can cause the sort of scenario that Wakefield and Vanden Bossche are warning about seems much less ridiculous. The operative word, of course, is “seems”, and I can certainly see how the emergence of variants like the Delta variant in a mere few months since Vanden Bossche’s viral letter might seem to support a conclusion that his prediction was correct. Of course, one also must point out that the best “incubator” for evolutionary selection pressure to produce more transmissible variants that can evade the immune response is to have a virus circulating freely among billions of people and that there is nothing special about “natural” immunity compared to vaccine-acquired immunity to SARS-CoV-2 that would make it any less of an evolutionary selection pressure to select for more transmissible variants, the claims of advocates of “natural herd immunity” as a way out of the pandemic notwithstanding.

One also has to acknowledge that Vanden Bossche has altered Wakefield’s argument somewhat in that his core claim was that it is mass vaccination during a pandemic that is dangerous:

Having been featured on Dr. Chris Martenson’s Peak Prosperity and Bret Weinstein’s Dark Horse podcast, Vanden Bossche has been outspoken – yet measured and reasoned – in his critiquing of mass vaccinations during the midst of the Covid pandemic. One of his main gripes with vaccination efforts is that vaccinating during the middle of a pandemic could potentially lead to a long runway of variants, some of which may evolve to be far more difficult to deal with than the original Covid virus.

One can’t help but counter that the beginning of mass measles vaccination occurred when measles was endemic, with millions of cases a year each and every year and around 5,000-6,000 deaths a year due to the disease. Measles vaccination nearly eliminated the disease, bringing it to the point where, before Andrew Wakefield, the disease had been reduced to very low frequency, with deaths rare.

The return of the revenge of predictions of global disaster by Geert Vanden Bossche

What is Geert Vanden Bossche up to these days? What is he claiming now? What’s led to all the social media chatter about his latest claims, examples of which include:

I can’t help but note right here why Bret Weinstein, promoter of the unproven (and almost certainly ineffective) anti-helminthic drug ivermectin that he is, loves Geert Vanden Bossche’s message. Right in the very first summary paragraph of his blog post, Vanden Bossche advocates for, in addition to “calling an immediate halt to the mass vaccination program” for COVID-19, “replacing it [the mass vaccination program] by widespread use of antiviral chemoprophylactics while dedicating massive public health resources to scaling early multidrug treaments of Covid-19 disease.”
You can also see why antivaxxers love the message, which is yet another variant (if you’ll excuse the term) of the favorite antivaccine trope that it is the vaccinated who spread disease, not the unvaccinated.

Vanden Bossche’s claim is the latest attempt to “flip the script” and, in response to the observation that it is the unvaccinated who can be a danger to the vaccinated by spreading disease given that no vaccine is 100% effective, has traditionally involved the claim that “shedding” of virus from the vaccine after vaccination can result in the infection of unvaccinated children who come into contact with the recently vaccinated. This claim dates back long before the pandemic and has long been used to spread fear, uncertainty, and doubt about attenuated live virus vaccines like the MMR and varicella (chickenpox) vaccines, leading to false claims before the pandemic that MMR strain measles was the “real” cause of measles outbreaks. Although shedding is not uncommon, cases of shedding leading to infection are vanishingly rare, making this basically a myth. Vaccinated children were not spreading measles and chickenpox. Antivaxxers have gone to ridiculous extremes trying to do the same thing with the mRNA- and adenovirus-based COVID-19 vaccines by claiming that the vaccinated “shed” the spike protein and that is causing people around them to become sick. Examples include, most famously, claims that women living with people who were vaccinated have suffered menstrual irregularities and even miscarriages as well as claims of general vague illnesses from “shed” spike protein. There is no good evidence to support these claims. As you will see, the invocation of the Delta variant, which can, it seems, be spread by vaccinated people, is just the latest “variant” of this attempt to “flip the script.”

So basically, Vanden Bossche is doubling down and pointing to the Delta variant as a harbinger of things to come. Of course, infectious disease epidemiologists had long been warning of something like the Delta variant and, like Vanden Bossche, warn that it could be a harbinger of worse variants to come. However, unlike Vanden Bossche, public health scientists see this variant as a warning that emphasizes the urgency to get as many people vaccinated as quickly as possible in order to forestall the emergence of still more variants. Unsurprisingly, Vanden Bossche doesn’t see the Delta variant the way that infectious disease epidemiologists do:

As of the early days of the mass vaccination campaigns, at least a few experts have been warning against the catastrophic impact such a program could have on global and individual health. Mass vaccination in the middle of a pandemic is prone to promoting selection and adaptation of immune escape variants that are featured by increasing infectiousness and resistance to spike protein (S)-directed antibodies (Abs), thereby diminishing protection in vaccinees and threatening the unvaccinated. This already explains why the WHO’s mass vaccination program is not only unable to generate herd immunity (HI) but even leads to substantial erosion of the population’s immune protective capacity. As the ongoing universal mass vaccination program will soon promote dominant propagation of highly infectious, neutralization escape mutants (i.e., so-called ‘S Ab-resistant variants’), naturally acquired, or vaccinal neutralizing Abs, will, indeed, no longer offer any protection to immunized individuals whereas high infectious pressure will continue to suppress the innate immune defense system of the nonvaccinated. This is to say that every further increase in vaccine coverage rates will further contribute to forcing the virus into resistance to neutralizing, S-specific Abs. Increased viral infectivity, combined with evasion from antiviral immunity, will inevitably result in an additional toll taken on human health and human lives. Immediate action needs, therefore, to be taken in order to dramatically reduce viral infectivity rates and to prevent selected immune escape variants from rapidly spreading through the entire population, whether vaccinated or not.

I can’t help but cite Andrew Wakefield again regarding measles, just to remind you how similar this argument is to Wakefield’s:

Antibiotic use has selected out multiply resistant, more dangerous, and more pathogenic strains of bacteria. This growing threat has led what many senior public health officials in the UK and the U.S. to describe as the “post-antibiotic apocalypse” and the “end of modern medicine.” It is estimated that 50,000 annual deaths occur in Europe and the U.S. from infections that “antibiotics have lost the power to treat.” So in fewer than 80 years, we have reached the point at which, for example, with prosthetic surgery, wards are being closed down, patients are being sent home, and operations are no longer possible, because once the prosthesis becomes infected with such bacteria, it is virtually impossible to get rid of them.

Are vaccines destined for a similar fate? It’s a very interesting question. One answer is, why not? For vaccines, resistance equates to strains of the microbe, the virus, or the bacteria that can elude the imperfect immunity created by the vaccine.

Let’s look at Vanden Bossche’s argument a bit further. On the surface, it appears to make sense. The problem with it, though, is simple. Each and every variant of concern (variants that either do or might lead to increased transmissibility of the virus or more severe disease) arose in populations with low vaccine uptake. For instance, the Delta variant was first identified in December 2020 in India. I can’t help but note that the first COVID-19 vaccines by Moderna and Pfizer were only just starting to be distributed then, and India was, aside from vaccine clinical trial participants, 100% unvaccinated, given that the variant had likely circulated at least a few weeks before being identified.

But, wait, you’re thinking: Didn’t the Delta variant spread in the US after the mass vaccination program was well under way? Oddly enough, Vanden Bossche doesn’t even refer to this rather obvious correlation that doesn’t mean causation, other than obliquely, noting that Delta is “now spreading very fast and as reserves of susceptible individuals become depleted as more and more youngsters become vaccinated.” This is, of course, not that surprising, given that this variant is so much more transmissible than the original SARS-CoV-2 and would be expected, all other aspects being equal, to outcompete less transmissible viruses. Moreover, the more transmissible the virus, the higher the percentage of the population that needs to be immune, either through vaccination or previous infection, to reach herd immunity. There’s a reason why measles, one of the most transmissible respiratory viruses there is, needs very high vaccine uptake for herd immunity.

So Vanden Bossche issues a dire warning:

In parallel with universal vaccination, more infectious strains have rapidly expanded in prevalence. According to molecular epidemiologists, Sars-CoV-2 is now also rapidly evolving towards resistance to S-specific Sars-CoV-2 Abs (9, 10). They have ascribed this to S-directed immune pressure that is now rapidly building up in the population. There can be no doubt that resistance to vaccinal Abs will be the endpoint of any mass vaccination program that uses modern vaccines during a pandemic of an acute self-limiting viral disease caused by a highly mutable virus.

Notice the cleverness of the wording. Vanden Bossche doesn’t say that these variants emerged after mass vaccination started, only that they have expanded in prevalence. Of course, in the absence of vaccination, one would naturally expect any strain that is more infectious to become more common in a population, particularly a variant (like Delta) that is several times more transmissible than the original Wuhan SARS-CoV-2. Given that few populations anywhere are anywhere near a level of vaccine uptake that one would expect to produce herd immunity, this claim is basically a meaningless observation, a correlation that doesn’t necessarily equal causation.

As noted by Alexis Madrigal, founder of the COVID Tracking Project:

One way to think about it, as the epidemiologist Ellie Murray has laid out, is that if Delta is as transmissible as the CDC thinks, we need a much higher percentage of our population vaccinated for immunizations and natural infection alone to cause the virus to peter out. Even when the huge majority of people in a given place have gotten the coronavirus or a shot, there might still be outbreaks, as the Brown University public-health expert Ashish Jha fears will happen in South Dakota after the Sturgis Motorcycle Rally.

These realities have already smashed the more optimistic projections of late spring, including my own. Having stared at these numbers for months and months with the COVID Tracking Project at The Atlantic, I never thought that we’d see hospitalization numbers higher than they were during the winter peak in any state. But here we are.

Madrigal also notes that there is a lot of randomness to where the worst outbreaks occur during pandemics, and this one is no different:

Back in the spring, when the variant we were most worried about was called Alpha, Michigan and almost Michigan alone got absolutely torched, matching its peak for hospitalizations from the winter. This didn’t happen anywhere else, though some epidemiologists expected it to, based on the experience of European countries. Alpha just kind of went away, and it seemed like the U.S. might be in the clear.

Enter Delta. In this surge, a piece of Missouri began to take off before the rest of the country. Would it be like Michigan? As we all now know, the answer was no. The southeastern United States is now experiencing huge outbreaks as many states come close to matching or surpassing their pandemic peaks in cases and hospitalizations.

The health-care system in north Florida is under pressure that few places have seen at any time during the entire pandemic. Why there? Why not somewhere else with similar vaccination rates and political opposition to viral countermeasures? No one knows with total certainty, and we’re unlikely to ever find out.

Vanden Bossche seems to sense that this is a weakness in his argument, which appears to be why (to me, at least) he pivots to the Lambda variant:

That viral resistance to S-specific neutralizing Abs may occur is anything but a myth. To my knowledge, the most compelling example of a variant capable of escaping neutralizing anti-S Abs is the lambda variant of Sars-CoV-2. This variant has incorporated an important change in the N-terminal domain (NTD) of its spike protein. This antigenic shift causes the virus to become resistant to neutralizing Abs. The change is caused by a deletion mutation and prevents neutralizing Abs from binding to the receptor-binding domain (RBD) of S (11). Thanks to this mutation, the lambda variant may gain a substantial competitive advantage if the virus is suddenly put under substantial and widespread S-directed immune pressure. A prominent surge in cases (as has been observed, for example, in several South American countries) may lead to a dramatic increase in S-directed immune pressure, especially in healthy people who become rapidly re-exposed to the virus as a result of a steep increase in infectious pressure. This explains how all of a sudden an immune escape mutant that is capable of resisting S-specific antibodies can rapidly become predominant in populations that experience a substantial surge in cases. But also populations that are subject to mass vaccination can exert strong immune pressure on viral infectiousness (i.e., on S protein). This suggests that high vaccine coverage rates eventually turn populations in excellent breeding grounds for such vaccine-resistant variants.

Again, most sources I find state that the Lambda variant was first identified in Peru in December 2020, but William Haseltine notes that the Lambda variant, which differs by 23 nucleotide changes and 18 amino acid changes from the original Wuhan strain, was identified in August 2020, again, before there were any vaccines, much less selective pressure to evade S-protein-based immunity due to a mass vaccination program. He also notes that 16 nucleotide mutations and 11 amino acid mutations lie outside the S gene that encodes the spike protein, adding that the effect “of any of these changes may be mitigated by changes in the ability of Lambda to enhance replication and improve down-regulation of the innate and adaptive immune response early in infection.” He has also noted that the variant is less susceptible to antibodies generated by the major vaccine used in South America.

In the US:

Genomic sequencing has identified 1,060 cases of Covid-19 caused by the Lambda variant in the United States so far, according to the independent data-sharing initiative GISAID. While that number is a far cry from the surge in cases caused by the Delta variant — representing about 83% of new cases in the US — infectious disease experts have said that Lambda is a variant they are watching closely.

So Lambda is currently driving a tiny fraction of the COVID-19 infections in the US. I’m a bit confused, too. Existing research (albeit still on a preprint server and not yet fully peer reviewed) found that after vaccination titers for Beta, Delta, Delta plus and, Lambda variants were decreased between 2.5- to 4-fold, which might sound like a lot, but is, as the authors described, only a modest decrease in neutralization, as they note in their conclusion:

In sera collected ~3 months post-second immunization, BNT162b2 and mRNA-1273 mRNA vaccine elicited antibodies neutralized the variants with a modest 3-fold average decrease in titer resulting in an average IC50 of about 1:600, a titer that is greater than that of convalescent sera and likely, in combination with post-vaccination T- and B-cell memory responses, to provide durable protection.

In other words, Lambda is basically no more resistant to vaccine-induced antibody-mediate immunity than Delta or Beta, with a modest decrease in the titer needed to neutralize the spike protein. What this will mean in the real world remains to be determined by measuring the effectiveness of the various COVID-19 vaccines against these variants, but there is plenty of reason to conclude that the vaccines offer considerable protection against at least severe disease from these variants. The authors even say so!

But the innate immune system!

Antibodies alone are not the be-all and end-all of the immune system. That’s why Vanden Bossche also tries to do a bit of a shuffle in his arguments by invoking the innate immune system (as opposed to the adaptive immune response, which is the immune response provoked by a vaccine or infection, a specific response to the antigen challenge seen by the immune system). Early in the post, VandenBossche writes:

Innate immunity critically contributes to protecting a population from Covid-19. This is why children and healthy people (i.e., not immune suppressed and without underlying disease) are enjoying a significant degree of protection from Covid-19 disease. Natural, innate antibodies (Abs) and Natural Killer (NK) cells can target non-mutable common structures in otherwise highly mutating viruses and hence, deal with all Sars-CoV-2 variants (1)

This is, of course, largely speculation. The reference cited is a review article about animal models looking at innate antibodies (again, antibodies present in the body that weren’t induced by infection or antigen challenge and that were there before any such challenge) that doesn’t even look at SARS-CoV-2 or even other coronaviruses. He also cites other articles, but one only discusses what “innate antibodies” are, while the other discusses how such antibodies might be the “bridge” between innate and adaptive immunity. Basically, it’s all speculation without good experimental or clinical evidence. There has been lots of speculation why children suffer severe disease and complications so much less frequently than adults, particularly older adults, but if there is a well-accepted explanation for the differential virulence of COVID-19 that is based on age I am as yet unaware of it.

This recent review notes several possible reasons:

Factors proposed to explain the difference in severity of COVID-19 in children and adults include those that put adults at higher risk and those that protect children. The former include: (1) age-related increase in endothelial damage and changes in clotting function; (2) higher density, increased affinity and different distribution of angiotensin converting enzyme 2 receptors and transmembrane serine protease 2; (3) pre-existing coronavirus antibodies (including antibody-dependent enhancement) and T cells; (4) immunosenescence and inflammaging, including the effects of chronic cytomegalovirus infection; (5) a higher prevalence of comorbidities associated with severe COVID-19 and (6) lower levels of vitamin D. Factors that might protect children include: (1) differences in innate and adaptive immunity; (2) more frequent recurrent and concurrent infections; (3) pre-existing immunity to coronaviruses; (4) differences in microbiota; (5) higher levels of melatonin; (6) protective off-target effects of live vaccines and (7) lower intensity of exposure to SARS-CoV-2.

Notice how Vanden Bossche zeroed in like a laser on innate immunity, when there are several other plausible contributors to this difference in severity of COVID-19 in children compared to adults. (I’m also guessing that he doesn’t like that bit about potential nonspecific effects of live vaccines.)

That doesn’t stop Vanden Bossche, though. As you read this quote, remember that he, just like Wakefield, is trying to develop a competing COVID-19 vaccine based on “innate immunity,” specifically natural killer cells (more on what they are in a moment):

Innate immunity critically contributes to protecting a population from Covid-19. This is why children and healthy people (i.e., not immune suppressed and without underlying disease) are enjoying a significant degree of protection from Covid-19 disease. Natural, innate antibodies (Abs) and Natural Killer (NK) cells can target non-mutable common structures in otherwise highly mutating viruses and hence, deal with all Sars-CoV-2 variants (1). However, as they merely serve a first line of immune defense and have relatively low affinity, they’re not armed well enough to deal with high concentrations of pathogens (1, 2, 3). Although our innate immune defense system can be considered a very potent natural bioweapon against Sars-CoV-2, it is populated by Abs that can readily be outcompeted by spike protein (S)-specific Abs. This is because the binding affinity of antigen (Ag)-specific Abs for a specific antigen is much higher than the affinity of innate, polyreactive Abs for the same antigen (the latter primarily bind to multiple surface-expressed binding sites(*1) through multivalent interactions (*2); 3, 6, 7). This biophysical phenomenon already explains why morbidity and mortality rates tend to increase with increased infectious viral pressure (e.g., due to enhanced intrinsic infectiousness of the circulating virus or due to overcrowding, mass gatherings, close contacts etc., especially if combined with poor hygiene and housing conditions).

Again, this is all speculation and ignores a lot of other science. But of course to Vanden Bossche, it has to be the innate immune system, preexisting antibodies, and natural killer cells, which are “early responders” in the immune system that are unique in that they can recognize and kill stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction and were named “natural killers” because it was observed that they do not require activation to kill cells that are missing “self” markers.

Flipping the script

Vanden Bossche also channels a favorite antivaccine talking point regarding COVID-19 vaccines:

As abundantly reported in the literature and social media, vaccinated subjects do not only spread Sars-CoV-2 variants (*4) but are now also increasingly developing symptomatic infections (*5).

This has been widely discussed in the media, as well as in the scientific literature, for instance, by Madrigal:

But it’s also become clear that vaccinated people who do get infected can spread the virus. The most recent piece of evidence came when American scientists were able to culture virus from samples taken from vaccinated people who’d gotten infected. Those same people showed similar viral loads to unvaccinated people. And yes, even those with asymptomatic infections.

Although that’s bad news, there is some good news too: Breakthrough infections appear to be significantly shorter than infections in the unvaccinated. That would reduce the amount of time that people with breakthrough infections could spread the virus.

There will undoubtedly be many more studies along these lines, and the papers cited above are preprints, meaning that they have not yet been peer-reviewed. But the data, including unpublished studies cited by public-health officials, are pointing in the same direction: Breakthrough infections are happening. And when they do, those people can spread the virus.

I always like to reemphasize here that, of course, some vaccinated people become infected. That was always expected, because no vaccine is 100% effective. Contrary to antivaxxers’ claims that these breakthrough infections mean that the vaccines are useless, less than 100% effectiveness is still effective, just not perfect. So, yes, vaccinated people can be infected with SARS-CoV-2, particularly the Delta variant. However, they are much less likely to become seriously ill because of it. Once infected with Delta, vaccinated people can transmit the virus to others. Also, as you might recall from the frenzied reporting when the CDC announced its findings and started recommending indoor masking again, vaccinated people infected with Delta can develop levels of virus in their respiratory system equal to what is observed in infected unvaccinated people, but, again, it appears that virus levels fall more quickly than in unvaccinated people and remain infectious for a shorter period of time.

This goes back to the concept of sterilizing immunity, in which the immunity of a vaccine is so effective that the virus cannot replicate in the vaccinated individual sufficiently to gain a foothold and cause infection, much less be transmissible by that person. In reality, sterilizing immunity exists for vaccines on a spectrum, as described in January in Scientific American:

Although many vaccines widely used today (against measles, for example) produce very effective sterilizing immunity, others, such as the hepatitis B vaccine, do not. With these vaccines, an individual’s immune system is trained to prevent illness, yet the pathogen can persist in that person’s body, potentially allowing them to infect others. A lack of sterilizing immunity means that the pathogen can continue to circulate in a population, where it may cause illness in unvaccinated and vulnerable people or evolve to evade our immune responses, Bowdish explains.

And an example:

The case of rotavirus—which causes severe vomiting and watery diarrhea and is especially dangerous to infants and young children—is fairly straightforward. Vaccination limits, but does not stop, the pathogen from replicating. As such, it does not protect against mild disease. By reducing an infected person’s viral load, however, it decreases transmission, providing substantial indirect protection. According to the Centers for Disease Control, four to 10 years after the 2006 introduction of a rotavirus vaccine in the U.S., the number of positive tests for the disease fell by as much as 74 to 90 percent.

Another favorite example cited by antivaxxers is pertussis, because the vaccine doesn’t produce sterilizing immunity:

For example, vaccines against Bordetella pertussis, the primary bacterium that causes whooping cough, or pertussis, do a great job of preventing illness but do not entirely clear the pathogen. Rather, as B. pertussis replicates in the upper respiratory tract, vaccine-induced antibodies apply pressure via natural selection to weed out bacteria whose disease-causing genes are turned on. Because these same genes are responsible for the parts of the microorganisms that are targeted by antibodies, bacteria that keep them turned off evade the immune response and hang out undetected in the upper respiratory tract, Bowdish explains. This becomes a problem when someone with a naive immune system, such as an infant, contracts the pathogen. In the absence of antibodies, B. pertussis‘s disease-causing genes become activated again, causing illness. Nevertheless, the introduction of pertussis vaccines in the 1940s cut annual U.S. cases from more than 100,000 to fewer than 10,000 by 1965. In the 1980s cases began slowly climbing again as parents increasingly refused to vaccinate their children. Today there is renewed focus on reducing the chance of exposure and getting antibodies to infants by immunizing pregnant women and new mothers.

Again, in medicine, as in life, nothing is 100% certain except that each and every one of us will one day die, and efficacy for any intervention exists on a spectrum, and even a nonsterilizing vaccine can be very, very useful:

In a paper in the October 2020 issue of the American Journal of Preventive Medicine, researchers modeled what a COVID-19 vaccine with varying types of protection could mean. They found that if a vaccine protects 80 percent of those immunized and 75 percent of the population is vaccinated, it could largely end an epidemic without other measures such as social distancing. “Otherwise, you won’t be able to rely on the vaccine to return us to ‘normal,'” says Bruce Y. Lee, a co-author of the paper and a professor at the CUNY Graduate School of Public Health and Health Policy. That is, if the vaccine only prevents disease or reduces viral shedding rather than eliminating it, additional public health measures may still be necessary. Even so, Lee stressed that a widespread nonsterilizing vaccine could still reduce burden on the health care system and save lives.

You might note that antivaccine “thinking” tends to be black and white. Either the vaccine is 100% effective, or it’s crap; the vaccine is either 100% safe, or it’s deadly. Like Vanden Bossche, they are very clever at sounding complex and nuanced in the service of demonizing vaccines. Vanden Bossche tries to impress with jargon and his handwaving invocation of variants coupled with invocations of natural killer cells and the innate immune system, and it does sound very impressive indeed. However, at its heart, it’s all speculation without any firm evidence, as well as a “reimagining” (if you will) of the old-fashioned antivaccine tropes that vaccines are (1) ineffective (Vanden Bossche’s claim that they don’t work against variants); (2) dangerous; and (3) make the vaccinated dangerous to the unvaccinated (Vanden Bossche’s claim that vaccines drive the evolution of more transmissible and dangerous variants).

Is it possible that SARS-CoV-2 could evolve variants that evade immunity from vaccines? Of course. Vaccination is a selective pressure, but it’s just one of many, and the current crop of variants all evolved before there even was a mass vaccination program. The bottom line is that the best way to forestall the development of further variants, one or more of which might be able to evade the immune response, whether due to prior infection or due to vaccination, is by vaccinating as many people as possible as fast as possible and following public health interventions:

We do not know yet whether this variant is more concerning than the Delta variant,” pharmacist and epidemiologists Dr. Ravina Kullar, who is an expert with the Infectious Diseases Society of America, wrote in an email on Friday.

“There needs to be extensive genomic surveillance studies that are done to assess how the vaccines’ efficacy is affected by the Lambda variant,” Kullar wrote. Until Covid-19 cases overall decrease, “the best way to prevent the emergence of more variants is getting fully vaccinated, not traveling internationally, and following strict infection prevention measures including wearing a face mask, physically distancing from others, and not attending large social gatherings.”

The CDC concurs. The bottom line is that the best conditions for the emergence of more dangerous and transmissible variants are when SARS-CoV-2 is spreading unchecked all over the world through billions of people. The best way to decrease the chances of variants like this emerging is to do whatever is feasible to decrease transmission and thereby dramatically decrease the number of people being infected. The vaccines work, but probably not as well for the Delta variant. Moreover, vaccination doesn’t have to completely block transmission to be effective in helping to end the pandemic. Finally, Vanden Bossche hasn’t said anything new compared to his previous claims. He’s just pointed to the emergence of more transmissible variants, which happened before the mass vaccination program, and blamed the vaccine for them.