Tag Archives: Natural Immunity

In Praise of Voluntary Vaccination

31 Tuesday Aug 2021

Posted by in Coronavirus, Vaccinations

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I was vaccinated in March and early April and I’m damn glad to have done it. I have certain co-morbidities, and I’m of an age at which contracting COVID seems like a very bad idea, I felt a little run-down on the day after my second jab, but that was my only side effect, notwithstanding the unending litany of antivax hysterics to which we’ve all been subjected (even on certain sites to which I contribute).

Freedom Without Misinformation

In the context of the pandemic, it’s important to take a stand for liberty. In that spirit, I oppose the imposition of mandates requiring face masks and vaccinations against COVID. Furthermore, vaccination is at best unnecessary for those having acquired immunity from infection and for those at low risk, especially children. In fact, the younger, healthier, and fitter you are, the less important it is to be vaccinated.

It’s disappointing, however, to see completely innumerate people cite statistics purporting to show that COVID-19 vaccines are deadly or even particularly dangerous to those lacking contra-indications. Far worse, and far more idiotic, is to suggest that a conspiracy is afoot to kill large numbers of people via vaccination! I’m truly embarrassed to hear individuals who otherwise share my libertarian ideals say such irresponsible bullshit.

While the COVID vaccines seem to have more frequent side effects than earlier vaccines, they are not particularly risky. I’ll discuss the safety of the COVID vaccines in what follows. Even minuscule risks are unacceptable to some individuals, which of course is their right. However, others find these risks acceptable considering the far greater dangers posed by the early strains of COVID and even the more recent but less deadly Delta variant.

Unverified Adverse Events

The vaccine scaremongers often quote statistics from the CDC’s Vaccine Adverse Reporting Events System (VAERS). Here’s a disclaimer about the system from the CDC’s web site:

“Healthcare providers, vaccine manufacturers, and the public can submit reports to VAERS. While very important in monitoring vaccine safety, VAERS reports alone cannot be used to determine if a vaccine caused or contributed to an adverse event or illness. The reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable.”

All kinds of reports are submitted alleging adverse events. For example, one observer cites the following reports from the system:

The link above refers to the following report as “Hulk Syndrome”, which was alleged to have been a side effect of the MMR vaccine:

Finally, we have this report related to the Pfizer COVID vaccine:

In case that’s hard to read, it claims that a COVID vaccine caused a third arm to grow from the reporting individual’s forehead, which constantly slaps him or her while trying to sleep. This report is a case of wonderful sarcasm, but it was submitted to VAERS! The real lesson is that the VAERS system collects many unverified accounts of side effects, so the aggregate counts of adverse events are not reliable, even by the CDC’s admission.

A More Sober Risk Assessment

Therefore, the VAERS system has obvious limitations. But even stipulating the use of VAERS reports, the risks of the COVID vaccines are vanishingly low. For example, roughly 198 million people in the U.S. have received at least one dose of a vaccine. As of last week, there had been about 13,600 reports of post-vaccination death in VAERS. The raw number is very high, and I don’t wish to minimize the seriousness of those losses. Nevertheless, if those deaths were all attributable to vaccination, and that is a BIG “if”, the risk of death from vaccination to-date is just 0.007%. That is seven thousandth of 1%. 

To put those VAERS deaths into perspective, I should first add the caveat that I am highly skeptical of the COVID case and death statistics. Nevertheless, let’s take the official U.S. COVID death toll of 646,000 at face value. I’m also treating reported vaccine deaths from VAERS at face value, which is a huge stretch. So, we have COVID mortality of 0.2% of the U.S. population, which is more than 28 times the risk of death from vaccination. I grant you the risk posed by COVID is lower going forward than in the past, which is due both to vaccinations and the declining virulence of the virus itself.

There are a range of vaccine side effects reported in VAERS, from pain near the injection site to such alarming conditions as anaphylaxis, Bell’s Palsy, and myocarditis/pericarditis. VAERS would attribute over 54,000 hospitalizations to the vaccines, a rate of 3 hundredths of one percent of those receiving at least one dose. Like COVID deaths, the number of COVID hospitalizations is likely inflated. Still, at 1.9% of the U.S. population, the risk of hospitalization from COVID is 68 times that of hospitalization from vaccine side effects reported in VAERS.

A large share of VAERS reports, covering all adverse events, are from middle aged individuals. It’s unclear how concentrated that reporting is among those with co-morbidities, including obesity, but I suspect they are heavily represented.

Coincidental Events

Perhaps less obvious is that many sincere reports to VAERS from both the public and health care providers represent coincidental events. A number of states have given heavy vaccine priority to the elderly and those with co-morbidities, and demand from those groups has been disproportionate in any case. Most of the VAERS-reported deaths also happen to be among the elderly and co-morbids.

For example, more than 38% of VAERS death reports come from the 80+ age cohort, accounting for roughly 5,200 deaths. That’s four hundredths of one percent of the 12.9 million people of ages 80+ in the U.S., most of whom have been vaccinated. Well over 1.2 million 80+ year-olds can be expected to die each year under normal circumstances. That a few would occur within days, weeks, or months of a vaccination should be expected. Furthermore, it would not be surprising, given the controversy surrounding vaccines and the suggestive power of antivax propaganda, for families or some caregivers to imagine a connection between vaccination and subsequent death. File a report! Who knows? Perhaps a class action award might be in it someday.

This is not to deny that a small number of individuals could be in such weakened states, or perhaps have unknown vulnerabilities, that the vaccines have catastrophic consequences. No doubt there are a few deaths precipitated by COVID vaccines in combination with other conditions. However, a large share of the deaths reported to VAERS are likely to have been coincidental. Likewise, people develop conditions all the time… sore joints, rashes, coughs, and headaches. It runs the gamut. Some of the VAERS reports of a less serious nature are undoubtedly coincidental, and perhaps some are due to the vivid imaginations of a subset of those having consented to the vaccine with great reluctance.

What Kills and What Doesn’t

Everything comes with a risk, and tradeoffs between risks must be balanced. The COVID pandemic was deadly, and I’ll be the first to admit that I underestimated its potential to kill. However, its deadliness was magnified by the non-pharmaceutical interventions imposed in many jurisdictions. Lockdowns and closures took a massive toll on the health of the population, cutting short many lives due to economic and personal despair as well as deferred and cancelled health care. While those interventions were deadly, I do not believe that kind of harm was intended. I do suspect the concomitant assault on liberty was welcomed in certain circles.

There are certainly downsides to the COVID vaccines. There have been more side effects and deaths than have ever been reported relative to earlier vaccines. It’s also a shame that public health authorities refuse to recognize the superior effects of natural immunity and the heightened risk of vaccinations to those with prior infections. And it’s a travesty that “vaccine passports” are now being demanded for various forms of travel, entertainment, and entry to some places of business. Despite these issues, it’s blatantly false to assert that the vaccines are generally harmful. Many more of the remaining vaccine-hesitant can benefit from vaccination. Let’s advocate for better assessments of risk by age and co-morbidity, and simply avoid the vaccines if that is your preference.

Addendum: I just came across this nice piece entitled “A Statistical Analysis of COVID-19 Breakthrough Infections and Deaths“. I thought I should share the link in case anyone supposes that so-called breakthrough infections somehow invalidate some of the comparisons I made above. This chart is particularly revealing:

On the Meaning of Herd Immunity

09 Saturday May 2020

Posted by in Pandemic, Public Health, Risk

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Immunity doesn’t mean you won’t catch the virus. It means you aren’t terribly susceptible to its effects if you do catch it. There is great variation in the population with respect to susceptibility. This simple point may help to sweep away confusion over the meaning of “herd immunity” and what share of the population must be infected to achieve it.

Philippe Lemoine discusses this point in his call for an “honest debate about herd immunity“. He reproduces the following chart, which appeared in this NY Times piece by Carl T. Bergstrom and Natalie Dean:

Herd immunity, as defined by Bergstrom and Dean, occurs when there are sufficiently few susceptible individuals remaining in the population to whom the actively-infected can pass the virus. The number of susceptible individuals shrinks over time as more individuals are infected. The chart indicates that new infections will continue after herd immunity is achieved, but the contagion recedes because fewer additional infections are possible.

We tend to think of the immune population as those having already been exposed to the virus, and who have recovered. Those individuals have antibodies specifically targeted at the antigens produced by the virus. But many others have a natural immunity. That is, their immune systems have a natural ability to adapt to the virus.

Heterogeneity

At any point in a pandemic, the uninfected population covers a spectrum of individuals ranging from the highly susceptible to the hardly and non-susceptible. Immunity, in that sense, is a matter of degree. The point is that the number of susceptible individuals doesn’t start at 100%, as most discussions of herd immunity imply, but something much smaller. If a relatively high share of the population has low susceptibility, the virus won’t have to infect such a large share of the population to achieve effective herd immunity.

The apparent differences in susceptibility across segments of the population may be the key to early herd immunity. We’ve known for a while that the elderly and those with pre-existing conditions are highly vulnerable. Otherwise, youth and good health are associated with low vulnerability.

Lemoine references a paper written by several epidemiologists showing that “variation in susceptibility” to Covid-19 “lowers the herd immunity threshold”:

“Although estimates vary, it is currently believed that herd immunity to SARS-CoV-2 requires 60-70% of the population to be immune. Here we show that variation in susceptibility or exposure to infection can reduce these estimates. Achieving accurate estimates of heterogeneity for SARS-CoV-2 is therefore of paramount importance in controlling the COVID-19 pandemic.”

The chart below is from that paper. It shows a measure of this variation on the horizontal axis. The colored, vertical lines show estimates of historical variation in susceptibility to historical viral episodes. The dashed line shows the required exposure for herd immunity as a function of this measure of heterogeneity.

Their models show that under reasonable assumptions about heterogeneity, the reduction in the herd immunity threshold (in terms of the percent infected) may be dramatic, to perhaps less than 20%.

Then there are these tweets from Marc Lipsitch, who links to this study:

“As an illustration we show that if R0=2.5 in an age-structured community with mixing rates fitted to social activity studies, and also categorizing individuals into three categories: low active, average active and high active, and where preventive measures affect all mixing rates proportionally, then the disease-induced herd immunity level is hD=43% rather than hC=1−1/2.5=60%.”

Even the celebrated Dr. Bergstrom now admits, somewhat grudgingly, that hereogeniety reduces the herd immunity threshold, though he doesn’t think the difference is large enough to change the policy conversation. Lipsitch also is cautious about the implications.

Augmented Heterogeneity

Theoretically, social distancing reduces the herd immunity threshold. That’s because infected but “distanced” people are less likely to come into close contact with the susceptible. However, that holds only so long as distancing lasts. John Cochrane discusses this at length here. Social distancing compounds the mitigating effect of heterogeneity, reducing the infected share of the population required for herd immunity.

Another compounding effect on heterogeneity arises from the variability of initial viral load on infection (IVL), basically the amount of the virus transmitted to a new host. Zvi Mowshowitz discusses its potential importance and what it might imply about distancing, lockdowns, and the course of the pandemic. In any particular case, a weak IVL can turn into a severe infection and vice versa. In large numbers, however, IVL is likely to bear a positive relationship to severity. Mowshowitz explains that a low IVL can give one’s immune system a head start on the virus. Nursing home infections, taking place in enclosed, relatively cold and dry environments, are likely to involve heavy IVLs. In fact, so-called household infections tend to involve heavier IVLs than infections contracted outside of households. And, of course, you are very unlikely to catch Covid outdoors at all.

Further Discussion

How close are we to herd immunity? Perhaps much closer than we thought, but maybe not close enough to let down our guard. Almost 80% of the population is less than 60 years of age. However, according to this analysis, about 45% of the adult population (excluding nursing home residents) have any of six conditions indicating elevated risk of susceptibility to Covid-19 relative to young individuals with no co-morbidities. The absolute level of risk might not be “high” in many of those cases, but it is elevated. Again, children have extremely low susceptibility based on what we’ve seen so far.

This is supported by the transmission dynamics discussed in this Twitter thread by Dr. Muge Cevik. She concludes:

“In summary: While the infectious inoculum required for infection is unknown, these studies indicate that close & prolonged contact is required for #COVID19 transmission. The risk is highest in enclosed environments; household, long-term care facilities and public transport. …

Although limited, these studies so far indicate that susceptibility to infection increases with age (highest >60y) and growing evidence suggests children are less susceptible, are infrequently responsible for household transmission, are not the main drivers of this epidemic.”

Targeted isolation of the highly susceptible in nursing homes, as well as various forms of public “distancing aid” to the independent elderly or those with co-morbidities, is likely to achieve large reductions in the effective herd immunity ratio at low cost relative to general lockdowns.

The existence of so-called super-spreaders is another source of heterogeneity, and one that lends itself to targeting with limitations or cancellations of public events and large gatherings. What’s amazing about this is how the super-spreader phenomenon can lead to the combustion of large “hot spots” in infections even when the average reproduction rate of the virus is low (R0 < 1). This is nicely illustrated by Christopher Moore of the Santa Fe Institute. Super-spreading also implies, however, that while herd immunity signals a reduction in new infections and declines in the actively infected population, “hot spots” may continue to flare up in a seemingly random fashion. The consequences will depend on how susceptible individuals are protected, or on how they choose to mitigate risks themselves.

Conclusion

I’ve heard too many casual references to herd immunity requiring something like 70% of the population to be infected. It’s not that high. Many individuals already have a sort of natural immunity. Recognition of this heterogeneity has driven a shift in the emphasis of policy discussions to the idea of targeted lockdowns, rather than the kind of indiscriminate “dumb” lockdowns we’ve seen. The economic consequences of shifting from broad to targeted lockdowns would be massive. And why not? The health care system has loads of excess capacity, and Covid infection fatality risk (IFR) is turning out to be much lower than the early, naive estimates we were told to expect, which were based on confirmed case fatality rates (CFRs).