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Showing posts with label Evolution. Show all posts
Showing posts with label Evolution. Show all posts

The Science Behind the Anti-Antibacterial Movement

Let me first start with this fundamental key:
 
One Bizarre Theory Replaces Another
 
In the early 19th century, a few scientists extrapolated a new and bizarre theory: that disease was caused by tiny organisms and each illness had a corresponding germ.
 
After a few years of examining sterile cultures slides and a bit of playing around with vaccines, these scientists were able to convince the world that their germ theory of disease was, indeed, true.
 
This outlook was convenient (and perhaps, perfectly poised to take root at this time in history during America’s industrialization) because it was methodical and specialized in its approach to understanding both the cause and treatment of disease. It allowed us to breakdown, the cause of an ailment to one small, fundamental unit which provided us a simpler way to understand a disease (ex. one germ for each disease). [*]
 
A treatment was then established based on this approach allowing generalized (‘one size fits all’) and massive quantities to be produced at an industrious scale. This approach was able to keep cost and time at a minimum while treating an increasing population. [*]
 
However, this mechanical approach to health is now diminishing…
 
Some biologists have even begun to speculate a new theory (I imagine just as absurd as germ theory was originally thought of back in the early 19th century): that humans are not individual entities, but rather complete ecosystems dependent on billions (100 trillion +) of bacteria and viruses (quadrillion +) to establish, maintain and actively influence health.[*][*]
 
Much of this information would have Pasteur rolling over in his grave…. who would think that viruses would be shown to help keep people disease free?[*][*]
 

Enter the field of Microbiomics.
 
If you have not heard of the human microbiome or microbiomics then, with great reverence, let me provide some mind blowing information for you to digest (no pun intended).
 
 
 

Microbiomics (….and why it’s absolutely mind blowing)
 
 
The ‘specific causes’ of diseases that revolutionized medicine a century ago is going through a conceptual evolution (time to get on board) – the way scientists think about disease and normal physiology is transforming. [*]
 
When I was in 7th grade, I remember the Human Genome Project being the next biggest and greatest thing science had going on…. now that it has been completed, however, a new phase has emerged: the Human Microbiome Project (HMP)….and it is changing everything. [*]
 
The HMP is an initiative to sequence the genomes of all the microbiological flora for a variety of body sites which play a “vital and interactive role” with our human DNA, immunity and disease. As bacteria, microbes and viruses in our bodies are modified under environmental pressure (ex. antibiotics and cesarean section birth), so is the regulation and replication of our genes (yes, our DNA). The two are intimately connected. [*] 
 

Far from being the ‘master molecule’ in our physiology, our DNA is demoted to simply another set of cellular genomes jostling for influence within us, reacting to and being regulated by, a set of microbial genomes that outnumber our own 10 to 1. [*]
 
 
Try to think of the bacteria, microbes and viruses that reside in our bodies as it’s own sensory motor organ which reacts much like our own nervous or immune system.[*]
 
Our microbiome encodes physiological traits that we were able to bypass in evolution; for example, the ability to “harvest certain nutrients and energy from food that would otherwise be lost because we lack the necessary digestive enzymes”. [*]
 
 
The Death of Germ Theory
 
The major conceptual doctrine of Pasteur’s germ theory is the role of causal pathogenic agents in disease. For example, diseases are separable from the patient and bacteria or virus in a human host equals disease. [*]
 
Even before the study of Microbiomics, it was clear that many individuals harbor dangerous bacteria (even at in large quantities) and suffer no ill effects.[*]
 
Certain diseases, such as herpes virus infection, which seem to fit neatly in the germ theory framework began to reveal a beneficial relationship that conferred immune advantages:

 

After clearance of acute infection, latent herpesvirus confers resistance to bacterial infection. To be specific, protection correlated with 100-fold reduction in bacterial burden in the spleen and liver.
 

2007 Nature [*]
 

“We now demonstrate that herpesvirus infection triggers systemic, PROFOUND IMMUNE MODULATION, with the potential to alter significantly the kinetics and nature of host response to foreign antigens.
 

Thus, whereas the immune evasion capabilities and lifelong persistence of herpesviruses are commonly viewed as solely pathogenic, our data suggest that latency is a SYMBIOTIC RELATIONSHIP with immune benefits for the host.”
 
 
So long we’ve swallowed the metaphor of an endless “war” on infectious diseases which involved a search for the microbial ‘cause’ of each and every disease  (of course, followed by the anti-microbial cure). This ideal has served its purpose and now we can no longer allow it to be our sole guide in medicine. [*]


 

“A new paradigm is needed that incorporates a more realistic and detailed picture of the dynamic interaction among and between host organisms and their diverse populations of microbes, only a fraction of which act as pathogens.” (Forum on Microbial Threats, 2006) [*]
 
 
A New Understanding of Disease

 

Quick Personal Backstory: My recent “antibiotic debacle”


About a month ago, my two year old was sent home from daycare for pink eye. I was expected to get a prescription for antibiotics for her to return. I was hesitant to say the least, my daughter has never received antibiotics and I wasn’t certain that all cases of conjunctivitis were caused by a bacteria. When we visited the nurse, she instructed me that only bacteria cause pink eye and my concern on delaying antibiotics was not sound. She went ahead and prescribed antibiotic eye drops.

 

Within 10 minutes of doing my own research once I returned home, I found this to be completely untrue. In fact, the majority of conjunctivitis cases are caused by a virus (NOT BACTERIA). Not to mention, the data very clearly illustrates that antibiotics for conjunctivitis is a complete over kill and often times does more harm than good.[*][*]
 

I made a deal with my husband, let’s wait one day before we administer the medication. We waited and her condition improved on its own. I suspect if we used the antibiotics, we would attribute her recovery to the drugs – luckily, we waited.
 

Medication we use via the ocular route (via eye drops) is just as important to research as ingested or injected drugs. Eye drop medication enters the bloodstream via mucous membranes lining the surface of the eye, the tear drainage system, and the nose. Once in the bloodstream, the medication can cause side effects in other parts of the body, including slow heart rate, dizziness and headaches.[*]

 

The outdated, traditional interpretation of disease correlates health as a matter of being “clean” and in order to obtain and maintain health we are advised to completely obliterate anything that’s not a human cell. [*]
 
Now, of course, microbiomics does not suggest health is all rainbows, ponies and singing kumbayah - our bacteria ecosystem can (and does) go awry. Certain species within us can overpopulate, resources decline, diversity is reduced (via antibiotics) and the interdependent processes can collapse.[*]
 
A new metaphor replaces the old – an understanding of ‘balance’ and ‘harmony’ supersedes the traditional thought of specific causation (one germ for each disease). Rather, human health is a matter of “having ones physiological process and predispositions aligned to promote homeostasis”. [*]
 

“It may turn out that diseases caused by microbial pathogens are best seen not so much as an invasion by a hostile organism, but rather as a kind of holistic dysfunction of the microbiome.” [*]
 

Simply revolutionary.
 
The greatest benefit to the health and wellness of a human body is not sterility, but rather “on maintenance of the symbiotic relationship between the host and the intestinal microbiotia”.[*]
 
This model, based on the latest science has to offer, suggests there are no diseases that exist separate from ourselves (ex. viruses floating around getting people sick) – only sick people whose processes within the body are not in balance. Recovering our health, therefor, is a matter of controlling the forces that influence the homeostasis within us.  Our health becomes a matter of our own responsibility. [*]
 
 
Antibiotics –Use with Extreme Caution (better yet, don’t use at all)
 
Our internal bacteria (particularly those located in the intestines) are essential to our health and “play an active role in nutrition, development, metabolism, pathogen resistance, and regulation of immune responses”. Antibiotic use, even for a short duration, has been “shown to disrupt these coevolved interactions leading to acute or chronic disease”.[*]
 
For every one human cell, there resides 10 bacteria cells within the human body (with viral particles expected to be a hundred times greater). Science, research and data continue to reaffirm that they play an active role in not only maintaining our normal physiology but also protecting us from: [*][*][*]
 
-respiratory infections
-acute intestinal infections
-allergies
-autism
-obesity
-type II diabetes
-cardiovascular diseases
-several forms of cancer
 

In addition to being numerous, our microbes are also “enormously varied” – with over 1,000 bacterial species residing within us. [*]

In fact, all plants and animals can be considered superorganisms; composed of a variety of species – bacterial and viral. [*] 

 
This variation in species is critical to health and is why antibiotics have been shown (repeatedly) to be permanently harmful (especially to children).
 

2007 The ISME Journal, Multidisciplinary Journal of Microbial Ecology
 

Long-term and persistent impact on human intestinal microbiota is a direct response from antibiotic exposure which never return to its original composition (during the 2 years of the study period). [*]
 
 
Antibiotics use in Children and Immune-mediated Disease
 
Antibiotics hold the possibility to be useful in some cases, but must be used with caution to protect long term health.
 
If you take anything away from reading this collection of data, please:
 

Several studies of antibiotic treatment has shown that the gut microbiota is profoundly and persistently altered by broad-spectrum antibiotic therapy. Data has shown that bacteria communities do not return to their initial state even after antibiotic treatment is withdrawn. [*]
 
During infancy and childhood, appropriate microbial stimulation and colonization is required for the development of a healthy, functional immune system. [*]
 
It is “well known that early life events occurring during critical windows of immune development can have long-term impact on immune-mediated disease. Antibiotic use in children has been shown, with significance, to increase such diseases as: diabetes, inflammatory bowel disease, asthma (requiring the use of inhaled corticosteroids), eczema. [*][*][*][*][*][*][*][*][*]
 
Antibiotic use must be critically evaluated, not just for ourselves but especially for children.  Each time we administer antibiotic medication it results in a ten-fold reduction in the amount of beneficial intestinal bacterial present. [*] 
 
With the use of antibiotic drugs, “significant alternations are seen in the expression of pro-inflammatory cytokines” and Th1 immune maturation which has profound effects on our immune system. [*][*]
 
 
Take Care of Your Health by Giving Your Microbiome Some Love

 
My preference is to eat and drink foods that promote a healthy flora (versus relying on supplements) while being mindful of the lifestyle choices that can hurt me (moderation is key, of course)….
 
Focus on Prebiotics
-Foods with prebiotics are garlic, onions, almonds and asparagus.
-Foods with the fiber inulin promote beneficial flora: bananas, high-fiber veggies like peas and beans.
 
Avoid Sugar (especially artificial sugar)
-Sugar and starch promote the growth of harmful bacteria in the body
-Yogurt may have probiotics, but they are often LOADED with sugar. Be careful!
 
Eat more Fermented Foods (just a quarter to a half cup per day will do ‘ya)
-Homemade sauerkraut, kefir (watch the sugar here too), kombucha, miso soup
 
Lifestyle
-Smoking, caffeine, alcohol, consuming heavily-processed foods

 
 
Conclusion
 
It may go completely against what we all have been taught in high school biology class, to think that bacteria and viruses make our immune system function better, but the science is becoming evident: A healthy, mature immune system depends on the constant intervention of beneficial bacteria.[*]
 
Humans (all mammals, in fact) have co-evolved over millions of years to establish a dynamic, complex check-&-balance system with our microbiota. It shouldn’t be all that surprising that our immune system (particularly our mucosal immune system) has developed an intricate connection that mediates the balance between health and disease.[*][*]
 

Both innate and adaptive immune function has evolved to require microbial interactions during their development. [*]
 

The microbiota provides critical signals that promote maturation of immune cells and tissues, leading to protection from infections by pathogens. [*]
 
We must become more aware of our symbiotic relationship with the bacteria within the body (especially our children’s). This starts with not stereotyping all bacteria as bad. In fact, although a few may be problematic, these account for far less than 1% that exist in our body.[*]

Take care of your ecosystem – it sure takes care of you!

 

You can't learn everything from the laboratory, that's what he used to say. The whole is more than the sum of its parts, he told us. The whole behaves differently from the parts, and has different properties. That's what he taught us, and he was right. It's out of fashion to say these days, when we spend our time scrutinizing the interactions of eukaryotic microbes, but it's true, nevertheless. It's still true.

(M. Drabble, The Sea Lady, 140–1)

A House of Cards: Vaccine-Induced Herd Immunity

House of Cards: a structure, situation, or institution that is insubstantial, shaky, or in constant danger of collapse [*]
 

 
In the 17th century, John Milton, a poet and writer, was the first to use this idiomatic expression and it has changed little in meaning over the centuries.
 
If you’ve ever attempted to build a house out of cards you know that it has the outward appearance of strength and  stability – all the while, the house is threatened by imminent collapse by a simple puff of air or a slight tilt of the foundation. 
 
This House of Cards analogy is ideal for understanding what herd immunity refers to when encompassing an introduction and reliance on a vaccine (and boosters) for protection throughout life.
 
*Incorporating a vaccination schedule (whether select, delay or on schedule) into your healthcare practice is your decision and, in my humble opinion, should be made on the grounds of examining data that both supports its use and challenges it. Vaccine induced immunity must be explored in further detail to ensure we are making the most sound choice for our children.
 
 

The Manipulation of Pre-existing Herd Immunity
 

Fundamentally, herd immunity exists/existed prior to vaccination.
 
With each national vaccine campaign, epidemiology (and herd immunity) is modified, benefiting some while actually placing another group at higher risk than before.[*][*][*][*]

While it is perceived beneficial that some vaccinated diseases have diminished over time (such as measles, chicken pox), it is very likely that these infections existed in a precise biological niche that was very much intentional – benefits in which our current understanding cannot yet comprehend.[*]

This massive disruption of previously acquired immunity results in a destabilization of epidemiologic patterns for many years.[* p297]
 
It also results in a precarious House of Cards - a reliance on vaccine-induced herd immunity.
 
 

Acquired immunity:  occurs as a result of exposure to an infectious agent or its antigens or of passive transfer of maternal antibody or immune lymphoid cells, renewed throughout life from continual cyclical re-exposure to the disease.[*]
 

Artificial immunity:  acquired immunity produced by deliberate exposure to an antigen.[*]
 
 
Infectious systems are highly complex biological structures.
 
In reference to herd immunity, a system may contain hundreds of demographic and epidemiological variables (which can be seen as the puff of air or tilt of the foundation in the House of Cards)  – all of which influence a population’s immunity to a virus/bacteria.
 
The science and intuition built on decades of practical epidemiological experience still often fail to predict outcomes/implications of vaccination programs. Below, is a brief list of some factors that may be considered threats to the house of vaccine-induced immunity.[*]
 
 

Dependence on Boosters Throughout Life
 
Currently, US vaccine recommendations target 17 “vaccine-preventable” diseases across a lifespan.
 
The U.S. Department of Health and Human Services’ Healthy People 2020 (which provides a 10-year national objectives for improving the health of all Americans) state that:
 

“As the demographics of the population continue to shift, public health and health care systems will need to expand their capacity to protect the growing needs of a diverse and aging population.”[*]
 
This means the House of Cards (vaccine-induced immunity) depends on you, me and grandma to get our booster vaccinations throughout life to maintain this newly invoked herd immunity.
 
Currently, we have boosters for young children, for preteens, for teens, for adults, for pregnant women, for college kids, for healthcare workers, for seniors – oh, and don’t forget your annual flu shot.[*]
 
The list is growing, not diminishing – this should raise concerns.
 
When vaccination initially began, the administration of a vaccine and the immunity to follow was thought to be similar to the naturally acquired immunity. However, we now know vaccines offer waning and incomplete protection which may lead to resurgence and epidemic outbreaks.[*]
 
Booster dose vaccination is not a pinch-hitter, rather boosters throughout life is just one of many fundamental keys to maintain vaccine-induced herd immunity within a population.
 
 

A Traveling Population
 
In 2012, over 30 million Americans traveled internationally, at the same time welcoming 67 million international visitors.[*][*] 
 
International travel (business/leisure) and migration represent a risk to herd immunity, particularly vaccine-induced herd immunity.[*]
 
According to the CDC, exposure to diseases brought into the US by American who travel abroad or from incoming visitors may overcome vaccine protection.[*][*]
 
Unfortunately, the manipulation of existing epidemiology does not change globally when a national vaccine program is implemented.  Unless we restrict international travel and migration, this pillar in the House of Cards will always be at risk of crumbling.
 

Example: 2010 Mumps outbreak in New Jersey and lower New York

Source of infection: 11-year-old boy at the camp. He had recently returned from the United Kingdom

Vaccine Protection: 88% had received at least 1 dose of mumps-containing vaccine, and 75% had received 2 doses[*][*][*]
 
 
The response to an outbreak such as the one in 2010: administer another booster.[*]
 
 

A Mother’s Protection (or Lack Thereof)
 
There’s nothing quite like a mother’s love and protection, particularly in the case of humoral and passive immunity.
 
Prior to vaccination, it was a newborn’s birthright to receive his/her mother’s antibodies to disease (intended to last long enough to prevent infection until immune function is mature enough).
 
Prior to the vaccination campaigns we see today, a newborn received antibodies against infectious diseases from their mother, who themselves had been infected as children (and re-exposed to the diseases later in life). Today, babies born to mothers who were vaccinated and never exposed to these diseases lack this protection.  
 

(2013) Babies born to unvaccinated mothers maintain their antibody protection about 61% longer than vaccinated mothers. That’s significant, a clear indication that vaccinations reduce newborn babies’ immunity to measles, and very likely to other infectious diseases for which vaccinations are given.[*]

 

(2001, 1994) Maternal antibodies erode faster than previously estimated, especially in infants who were born to mother’s that have been vaccinated.[*][*]
 
The protection this newborn population had prior to vaccination is being eroded with each national vaccine campaign.
 
One answer to alleviate this threat: targeting new vaccines for pregnant mothers.[*]
 
 

The Catch 22 of Disease Elimination and Wild-type boosters
 
An infectious disease has the ability to offer lasting protection. Even with natural immunity waning over time, subsequent enhancement (boost) is provided by asymptomatic encounters with the infection. [*]
 
However, when vaccination is introduced the prevalence of infection declines, which in turn reduces the amount of boosting and hence the level of immunity. What is more surprising is that the interaction between vaccination and waning immunity can lead to pronounced epidemic cycles.[*]
 
This data leads researchers to rest their hope of eliminating vaccinated diseases (‘vaccine-preventable disease’) by relying on protection promoted by circulating wild-type viruses.[*]
 
Nonsensically, that means we hope to attain elimination of disease while depending on the continuation of the wild-type disease.
 
??
 
How can you have elimination if the disease if it is still in circulation boosting vaccine-induced herd immunity?
 
 

Evolution
 
From the rise in methicillin-resistant Staphylococcus aureus (MRSA) causing deadly skin infections to the bacterial colonies on your hands evolving to resist your antibacterial soaps and hand gels, evolution is present in our daily lives.[*]
 
The two strongest examples of evolution in disease within our current vaccination programs is influenza and pertussis.
 
Of the former (influenza), everyone is well aware of – every year, starting in early September, we are reminded that the old vaccine we administered last year is useless and we need to get the updated vaccine to protect ourselves, our children and our community.[*]
 
The influenza virus experiences constant single-point mutations which renders the prior vaccine unidentifiable, requiring a new one every year.[*][*][*]         
 
Unfortunately, data continues to support that annual  influenza vaccination inhibits our body to fight other strains of flu not included in the vaccine and other respiratory virus infections.[*][*][*][*]
 
With the less discussed pertussis vaccine (the ‘ap’ part of the Tdap booster and the DTaP vaccine), mutation is more apparent than ever before but receives a lot less buzz.
 
If I had to render a guess as to why, it could be because of the key role the vaccine plays in the mutation of the bacteria.

 
 
Pertussis (aP) vaccination not only makes a person more susceptible to B. parapertussis infection but it also enhances the performance of the pathogen. Research completed in 2010 illustrates a 40-fold increase in B. parapertussis lung colony-forming units after vaccination of aP injections.[*][*]


(2012) Study completed by Kaiser Permanente Medical Center concluded that pertussis occurs more among vaccinated children than children not vaccinated for pertussis with the DtaP vaccine.[*]

 
The answer to alleviate this problem: earlier or more numerous booster doses of acellular pertussis vaccine.[*]
 

****
 
It seems the continual response to any weakness or flaw in vaccine-induced herd immunity is an increase in booster doses, occurring earlier and more often throughout life.
 
It is clear that each infectious system that has a current national vaccination program hold their own complex biological structure with numerous variables.

Putting the Herd (Immunity Debate) to Rest

Understanding infectious systems (and debating them) requires a person to be able to reason about highly complex biological structures, of which, contain hundreds of demographic and epidemiological variables.[*]

It seems commonplace in debates/discussions concerning herd immunity that extrapolating demands on others are made – particularly to maintain specific elimination thresholds (one example easily comes to mind: non-medical vaccine exemptions should be void to maintain herd immunity). 


Elimination Thresholds and the Dynamics of Immunity

Two authentic hazards arise when debates concerning herd immunity/vaccination rates place consistent emphasis on maintaining elimination thresholds (ie 90-95% vaccination rates)

(1) the debate begins to distract from the fundamental extreme dynamics of epidemic theory, particularly to herd immunity[* pg297]  

(2) the debate portrays a human life as a instrument in medicine that can/should be utilized in a societal defense against viruses/bacteria/disease. (the dismissal pertaining to an individual’s choice regarding a medical procedure)


For this post, I will only be addressing the first point (the complexities relating to the influences on herd immunity). To learn more about the second issue you can read this post.

I feel the need to address this particular point because in common debates regarding herd immunity (pertaining to national vaccination programs) a fundamental cornerstone of epidemiology is continually dismissed: the extreme dynamic consequences of the intrinsic nonlinearity of host-agent systems.[*] 

In laymens terms – this shit is complex.


Does Herd Immunity Exist?

Absolutely.

There is no denying that herd immunity is an extremely potent natural phenomenon which is altered by a multitude of influences (which I am going to attempt to list briefly a little later). In the presence of a national vaccine program, it is purposefully manipulated with the intention that the recognized gains will out weigh any known disadvantage(s) that might occur (financially, safety, policy, etc). [*]

In the United States, we rely on the ACIP to examine new (and current) vaccination campaigns of which must be weighed very cautiously. To intentionally modify the current existing herd immunity against a non-fatal, acute childhood disease can carry unfortunate characteristics such as protecting one population while actually placing another group at higher risk than before (ex varicella campaign).[*][*][*][*]


On the other hand, there are campaigns that historically have provided success. So far, the only infection to be eradicated worldwide is smallpox (variola major -WHO 1977). This accomplishment generated much optimism in the philosophy of eradication thresholds that other infectious diseases (such as measles and pertussis) were targeted.  Unfortunately, this thinking may have been misguided for many reasons: smallpox was unique given its low communicability, the high average age of infection, the ease of diagnosis and the stability of vaccine storage conditions.[*]


It is also important to reveal, that there are complete absences of herd immunity seen in several diseases (some of which we currently vaccinate against such as rubella, diphetheria, pertussis).[*]

The blanket justification of herd immunity in support of elimination thresholds for vaccination on the current US vaccine schedule has the very real potential in becoming a crude and one-dimensional debate.


The Fundamentals

When speaking of herd immunity in relationship to a national vaccination campaign, one must be specific to which disease they are discussing and they must show an understanding to the intricate nature of influences of immunity within the individual and within a community.

To begin, a foundation must be understood. Epidemic theory considers three variables: agent, host and environment (each of which has many components/interactions/influences in-and-of themselves).

Agent
An agent is any infectious pathogen. These vary in biological makeup, size, transmission, and habitat. In the construction of mathematical models of epidemics and herd immunity, all possible variations in all aspects of the agent's behavior (particularly in relation the host and the environment) must be taken into account.[*]

Host
The classification of a host is relevant when an agent invades a foreign entity (aka the host) resulting in a defensive immune response with the purpose of protection. Immunity attained can range from temporary to permanent. [*] 


What is of particular study is the host’s response with antibodies specific to the infectious antigen. These seropositive individuals are those who have current infections or who have experienced an infection in the past – moving them from the category of ‘infected’ to ‘recovered’.[*]    

Of course, when referring to the context of herd immunity, one must consider both the individual hosts and the population as a whole.


Environment
Consideration and concern is given to the environment and vicinity in which both the host and agent dwell. This can range from geographical heterogeneity to seasonal variations (again, for both host and agent).



Mathematical Modeling – SIR Model

Epidemiology gives birth to herd immunity theory when the first mathematical model examined how infectious agents affected large populations over time.[*][*][*]

Obviously, for ethical reasons and financial reasons (hopefully the former out weighs the later), experimentation or field trials are prohibitive – making mathematical modeling critical in making theoretical predictions of how a disease will spread and can be useful for evaluating control strategies (particularly in the case of a bio-weapon attacks).[*][*]

The Mass Action Principle (SIR) has been widely applied and accepted in epidemic theory since 1927 – when Kermack and McKendrick published 3 papers outlining and describing a mathematical model in which they considered a fixed population with 3 compartments: susceptible; infected; recovered (SIR).[*][*][*]


Susceptibles (S) – Individuals that are susceptible have, in the case of the basic SIR model, never been infected, and they are able to catch the disease. Once they have it, they move into the Infected compartment.[*]

Infected (I) – Infected individuals can spread the disease to susceptible individuals. The time they spend in the infected compartment is the infectious period, after which they enter the recovered compartment. [*]

Recovered (R) – immune to the disease or otherwise removed from the population. Individuals in the recovered compartment are assumed to be immune for life. [*]


In the SIR model, vaccination is equivalent to complete removal (aka transfer to the Recovered compartment). It is assumed that vaccinated individuals can not infect or be infected. [*] 

The above described SIR model is helpful although it is written using an equation that implies a deterministic model (no randomness with a continuous time). [*]

To account for this, the SIR model is the basis for other similar models (SEIS, MSIR, MSEIRS) that make small adjustments in its parameters that attempt to alleviate certain ‘real-world’ problems, for example:[*][*] 

SEIS  - considers the exposed or latent period of the disease (a person is not immediately infected).

MSEIRS – considers an infection that does not leave a lasting immunity in which individuals that have recovered will return to being susceptible again, moving back into the S compartment.

MSIR – considers a disease where an individual is born with a passive immunity from the mother.


Although mathematical equations are very useful in understanding basic principles and the interplay between variables, their assumptions can lead to oversimplification.[*][*]

My concern centers on the simplicity of many mathematical models, particularly in the face of such biological complexity. Especially useful tools in modern complex theories incorporate multiple algorithms and concepts of TCS (theoretical computer science), however these tools are not yet utilized and relatively unknown in epidemiology.[*][*]



Complexities of the Herd

There are several assumptions made in the formulation of the above mentioned equations. These assumptions have benefits and disadvantages.

Benefits may include being utilized for a general guide to risk assessment or a supportive piece to compare alternative policies/intervention – a wide-ranging compass to help make epidemiological decisions.

However, it is clear that to make the forecast more realistic, it is necessary to introduce more details in the disease dynamics. Models that incorporate even the most elaborate derivations omit important features.[* pg 296]

Here are a handful of features to begin to take into consideration that influence the dynamics of disease, immunity, transmission, and recovery.[*]


Geographical heterogeneity
This refers to gender (i.e. male-female ratios), age, and factors correlated with residence. Because of existing heterogeneity, estimated elimination thresholds vary between local communities – significant local differences in population dynamics arise which, consequently adjust estimates.[*][*]

Areas of similar dynamics and variation pertaining to heterogeneity:

• Age-Structured populations
• Variable infectivity
• High contact probabilities
• Persistence of pathogens within hosts
• Variations in infection risk by age group
• Limitation of application to a closed population (no immigration or emigration)[*]
• Demographic turnover (birth or death).[*]


Host genetic factors
A particularly new dynamic gaining more comprehension is the role of host genetic factors – this dynamic is critical because mathematical models rely on and individual within the population as having an equal probability as every other individual of contracting and transmitting a disease.[*][*][*]

Research is continuing to learn strategies to identify host genes responsible for resistance/susceptibility to particular agents and the relationship between vaccine efficacy and genetics.

Areas of similar dynamics and variation pertaining to host genetic/immuno factors:

• intra-host dynamics
• Maternal immunity


Spatial epidemiology
The most fundamental of these is the problem of defining the spatial location of the entities being studied. For example,

In regards to the study on human health, spatial position of humans can pertain to the area or point with where an individual/group live, or with a point located where they work, or by using a line to describe their weekly trips. Each variation has dramatic effects analysis and on the conclusions obtained.[*]

Other issue arise in the application of spatial analysis which includes the limitation of mathematical knowledge problems in computer based calculations.[*] 


Antigenic shift
Antigenic shift is contrasted with antigenic drift (a natural mutation over time). The issue with antigenic shift concerns our lack ability to forecast ability of viruses to alter their genetic makeup (quickly creating mutant antigens) and bypassing the antibody barrier a host/community.[*]


Phylodynamics
Viral phylodynamics examines how epidemiological, immunological, and evolutionary processes impact viral genetic variation.

Dynamics of transmission is considered at the level of cells within an infected host, individual hosts within a population, or entire populations of hosts.[*]

Currently, it is understood that viruses within similar hosts, such as hosts that reside in the same geographic region, are expected to be more closely related genetically if transmission occurs more commonly between them.[*]

Areas of similar dynamics and variation pertaining to phylodynamics:

• pathogen population genetics
• evolution and spread of resistance to immunity/medication
• Strain (biology) structure and interactions


Seasonal variations
There are several biologically distinct mechanisms in which seasonality and climate change impacts host-pathogen interactions. Strong pressures on population dynamics are exerted by temperature, rainfall, seasonality and climate change – responses can range from simple annual cycles to more complex multiyear fluctuations.[*][*]

Although scientists are only beginning to understand how seasonal external drivers influence the majority of host–parasite systems, empirical evidence strongly supports the strength and mechanisms of which seasonality alters the spread and persistence of infectious diseases. [*][*]

To present two examples for further understanding:

Agent: rotavirus.
Seasonal affects: winter peaks; timing shifts with latitude[*]

Agent: meningococcal meningitis
Seasonal affect: wind speed and low humidity affect respiratory/aerosol transmission[*]

Areas of similar dynamics and variation pertaining to seasonal variation:

• alterations in immune system defenses (weakened during winter and during harsh weather)
• periparturient rise (pregnant women lowering their own immunity to prevent harming the fetus)
• diseases that are cyclical in nature
• diseases that are seasonal in nature



Ending the Debate on Herd Immunity 

Agent-Host-Environment: This relationship is complex and depends on such factors as a precise course of infection (not only with an individual but within the demography of the host population). Other factors include duration of immunity (natural or artificially acquired), maternally derived protection, age-related changes in the intimacy of contacts – not to mention a prevailing level of genetic and spatial heterogeneity in both susceptibility and resistance to infection.[*]

There is no denying that mathematical models aid in defining details associated with infectious systems. Adjustments made to incorporate dynamic influences have the ability to make useful generalities and estimates – particularly to elimination thresholds and the course of infection within a population.[*] 

However, the science and intuition built on decades of practical epidemiological experience still often fail to predict outcomes/implications of vaccination programs.[*]

Each vaccination campaign entails a massive disruption of the previous balance which results in a destabilization of epidemiologic patterns for many years.[* p297]

...are vaccinated individuals the ones stepping outside the herd?

Herd immunity existed prior to vaccination.

Preceding national vaccination programs, epidemiological patterns of immunity/disease existed for the greater good. With each national vaccine campaign, epidemiology is modified (benefiting some and disadvantaging others).

While it is perceived beneficial that some vaccinated diseases have diminished over time (such as measles, chicken pox, rubella), it is very likely that these infections existed in a precise biological niche that was very much intentional – benefits in which our understanding can not yet comprehend.[*]

How exactly can the herd immunity debate end? 

(1) Accepting that the encompassing complexity of infectious disease (and nature in general) is not something human understanding will be able comprehend in entirety. Yes, artifical modification (via vaccine) can impart benefits – but it also exposes populations/individuals to disadvantages (many of which cannot be forecasted in advance) – implementation of vaccine programs must not be taken lightly nor forced upon a population without individual consent. 

(2) Above all else, voluntary consent married with adequate comprehension of each vaccine is fundamental as national vaccine campaigns develop and progress. This is whatshould be the underlying principle in discussions on herd immunity – NOT mandatory vaccination.



This post is dedicated to those families that have been deliberately and maliciously accused of ‘free riding’ off of vaccine-induced/artificial herd immunity – especially those who have been told this by a medical professional in hopes of altering a consent of vaccination.

I like to believe all parents are doing the best they can. Please choose what works best for your family while honoring the rights of others to make that same choice.