It’s true, polio has been eliminated in the United States.
But that doesn’t mean that we can stop vaccinating kids against polio yet.
Why Do We Still Vaccinate If Polio Has Been Eliminated?
For one thing, the last polio case in the United States was a lot more recent than 40 years ago.
What happened 40 years ago?
That was when we had the last endemic case of polio in the United States, in 1979. After that, in addition to cases of VAPP, there were at least 6 cases of imported paralytic poliomyelitis. In fact, the last case of wild polio in the United States was in 1993, just 26 years ago.
And just ten years ago, in 2009, was the very last case of VAPP, a patient with a long-standing combined immunodeficiency who was probably infected in the late 1990s, even though she didn’t develop paralysis until years later.
But still, why couldn’t we stop vaccinating against polio in the United States, even though polio isn’t eradicated yet? After all, we stopped using the smallpox vaccine in 1972, before smallpox was declared eradicated (1980).
While that is true, smallpox isn’t as contagious as polio and there hadn’t been a case of smallpox in the United States for over 30 years when we stopped using the vaccine.
Until wild polio is eradicated and the oral polio vaccine isn’t used anymore (OPV switch), we must continue to vaccinate against polio to prevent new outbreaks.
That is the polio eradication and endgame strategic plan.
Over the next few years, the world will hopefully switch to using just the injectable form of the polio vaccines, which eliminates the risk of VAPP.
But if we are so close, why not just stop vaccinating in those parts of the world that don’t have polio?
Because we are so close to eradicating polio.
Why take the risk of polio spreading from one of the remaining endemic countries, paralyzing kids, and putting eradication efforts further behind?
There is a lot more interest in polio these days, but not because we are close to eradicating this deadly disease, but rather because of the emergence of cases of acute flaccid myelitis (AFM).
Although the cases have a different cause, the symptoms of AFM are the same that we used to see during the outbreaks of polio that used to hit each summer in the pre-vaccine era.
Surprisingly, in most people, the poliovirus doesn’t actually cause any symptoms. They simply have an asymptomatic infection.
In some others, the poliovirus causes flu-like symptoms, including a fever, sore throat, nausea, and a headache – symptoms that last about 3 to 5 days.
Much more rarely, the poliovirus causes meningitis or paralysis.
It is these cases of paralytic polio that most people are aware of and that panicked parents during summers in the 1940s and 50s.
After having flu-like symptoms, those kids who would develop paralytic polio can develop pain and then flaccid paralysis.
“The most severe form, paralytic poliomyelitis, which is seen in less than 1% of patients, presents as excruciating episodes of pain in back and lower limbs. In children, the disease may present in biphasic form—a period of prodrome followed by a brief symptom-free period of 7 to 10 days and then appearance of asymmetrical paralysis of limbs. Flaccid paralysis is the hallmark with loss of deep tendon reflexes eventually.”
Mehndirattta et al on Poliomyelitis Historical Facts, Epidemiology, and Current Challenges in Eradication
Of course, polio wasn’t always called polio.
Other names have included infantile spinal paralysis, infantile paralysis, Heine-Medin disease, poliomyelitis anterior acuta, and acute anterior poliomyelitis.
The first use of the name “polio” came from Adolph Kussmaul, with his use of the term poliomyelitis anterior acuta, which was derived from the Greek polios “grey” and myelos “marrow” and itis “inflammation.” It was because he knew that it was caused by inflammation of the spinal cord gray matter, even if he didn’t know why.
Polio didn’t just suddenly appear in the middle of the 20th century though, it was likely around for ages.
In addition to an Egyptian funeral stele (a stone slab used as a monument) portraying Roma the Doorkeeper from 1500 BCE that suggests he had paralytic polio, archeologists have found evidence of polio in skeletons as far back as the Neolithic period.
Still, we don’t really know how long polio has been around and we don’t know why we began to see more cases in the mid-20th Century, although there are theories, including, ironically, about hygiene. While we often credit improved sanitation and hygiene for helping to reduce mortality from many diseases, some think that this actually set us up for polio outbreaks, as we were no longer exposed as infants, when we still had some maternal immunity.
The one thing that we do know is that we are on the verge of eradicating polio, as there are very cases now, in just a few countries.
Polio Timeline and Milestones
In addition to the more ancient discoveries about polio, there is a lot to learn about vaccines and vaccine-preventable diseases if we look at the major milestones of this important disease.
Although in the end it is a success story, the road to figuring out what caused polio symptoms and how polio could be prevented was very long.
Michael Underwood describes what is thought to be paralytic polio in his book A Treatise on the Diseases of Children, with General Directions for the Management of Infants from Birth in a section on “Debility of the Lower Extremities” (1789)
first reported outbreak of polio in Worksop, England (1835)
Jacob von Heine, head of an orthopedic hospital in Germany, publishes a monograph that describes 29 cases of paralytic polio, and actually attributes the condition to inflammation of the anterior horns of the spinal cord, although the cause was still not known (1840)
first use of the term poliomyelitis by Adolph Kussmaul (1874)
Nils August Bergenholtz reports on an outbreak of paralytic polio in Sweden (1881)
Karl-Oskar Medin, a pediatrician who reported on a polio epidemic in Sweden (1887), later presents his findings at the Tenth International Conference in Berlin (1890)
the first major outbreak in the United States is documented in Rutland County, Vermont and causes 132 cases of paralysis and 18 deaths (1894)
Ivar Wickman tracks cases of polio during an epidemic in Sweden in 1905 and was the first to suggest that polio was contagious and that you could get it from “those afflicted with the abortive type” (1907)
although they don’t actually identify the poliovirus, Dr. Karl Landsteiner and Dr. Erwin Popper identify that a virus causes polio when they inject material from the spinal cord of a child who had recently died with polio into the peritoneum of two monkeys, both of which soon developed paralytic polio (1908)
Simon Flexner, first discovers polio antibodies (1911), but unlike other researchers at the time, pushes the theory that polio was spread by the olfactory route, instead of the fecal-oral route, which was why we saw the development of nose sprays, etc., to try and prevent polio, none of which worked of course
a large polio epidemic in the United States causes at least 27,000 cases and 6,000 deaths (1916)
Philip Drinker and Louis Agassiz Shaw invent the first iron lung, the Drinker respirator (1929)
Frank M. Burnet and Jean Macnamara proposed that there were antigenically different strains of poliovirus (1931)
John R. Paul and James D. Trask help figure out how polio was spread by identifying the polio virus in human waste and sewage samples (1932)
Maurice Brodie and John Kolmer have unsuccessful field trials of early polio vaccines, including allergic reactions and vaccine induced polio because of poor attenuation (1935)
Sister Elizabeth Kenny establishes a clinic in Australia to treat polio survivors (1932) and later publishes her treatment recommendations, Infantile Paralysis and Cerebral Diplegia (1937)
the National Foundation for Infantile Paralysis is founded by FDR to stop polio (1937)
Carl Kling found traces of the poliovirus in the Stockholm sewage system (1942)
the Sister Kenny Institute is built in Minneapolis, as her treatment methods become widely accepted after years of controversy (1942)
the U.S. Army Neurotropic Virus Commission, including Albert Sabin, gets a grant from the NFIP to study polio in North Africa (1943)
Isabel Morgan actually developed the first inactivated polio vaccine, but only tested it on monkeys (1949)
John Enders, with T. H. Weller and F. C. Robbins, received the Nobel Prize in 1954 for their work on the cultivation of the poliomyelitis viruses (1949)
David Bodian creates the monkey model using field isolates of poliovirus and with Jonas Salk, identifies the three poliovirus serotyes (1950s)
Hilary Koprowki develops the first oral, live polio vaccine, (1950) although Sabin’s vaccine eventually gets licensed because it is thought to be less neurovirulent in monkeys and undergoes more testing
there are 58,000 cases of paralytic polio in the United States (1952)
Renato Dulbecco, with Marguerite Vogt, successfully grows and purifies polio virus (1952)
the Polio Pioneers vaccine field trial, led by Thomas Francis Jr., that proves that Jonas Salk’s polio vaccine is safe and effective begins (1954)
the WHO Western Pacific Region is declared polio free (2000)
the United States switches back to using the an inactivated polio vaccine because of concerns over VAPP (2000)
the WHO European Region is declared polio free (2002)
outbreak of vaccine derived polio among a group of unvaccinated Amish in Minnesota (2005)
last case of VAPP that was acquired outside the United States, an unvaccinated 22-year-old U.S. college student who became infected with polio vaccine virus while traveling in Costa Rica in a university-sponsored study-abroad program (2005)
last case of VAPP, a patient with a long-standing combined immunodeficiency who was probably infected in the late 1990s (2009)
Bob Sears says that it is okay to delay the polio vaccine on his alternative vaccine schedule because “we don’t have polio in the United States” (2015)
a global switch from trivalent OPV to bivalent OPV in routine immunization programs (2016)
polio remains endemic in just three countries, Afghanistan, Nigeria, and Pakistan (2018)
So it should be clear, that despite what some folks think, polio wasn’t conquered overnight. And Salk and Sabin obviously had a lot of help, although those are the names we most commonly hear connected with polio eradication.
“Until poliovirus transmission is interrupted in these countries, all countries remain at risk of importation of polio, especially vulnerable countries with weak public health and immunization services and travel or trade links to endemic countries.”
Global Polio Eradication Initiative on Endemic Countries
Breaking News – 158 cases of AFM in 36 states have been confirmed so far this year, with an additional 153 cases under investigation.
Since 2014, we have seen several outbreaks of acute flaccid paralysis (the sudden onset of weakness in one or more arms or legs) across the United States.
We don’t know, except we do know that these folks don’t have polio, even though folks continue to get confused because the kids are described as having a “polio-like” disease. Every case undergoes extensive testing, including testing for polio and other viral infections.
Do Vaccines Cause Acute Flaccid Myelitis?
Tragically, like some other conditions of unknown cause, some people have grasped onto the idea that AFP could be caused by vaccines.
“Of 14 patients with available information, 12 had previously received polio vaccine; one child and one adult were unvaccinated because of personal belief exemptions.”
Acute Flaccid Paralysis with Anterior Myelitis — California, June 2012–June 2014
It shouldn’t be surprising that there is absolutely no evidence that this is any type of vaccine injury.
Of nearly 350 cases of the acute flaccid myelitis (AFM), or the subtype of AFP that we have been seeing since 2014, we know that:
most cases occur in children
they have a magnetic resonance image (MRI) showing spinal cord lesion largely restricted to gray matter and spanning one or more vertebral segments
AFM can be caused by viruses, environmental toxins, and genetic disorders, although no common etiology has been found in recent cases
cases are occurring sporadically – after 120 cases in 34 states in 2014, there were only 24 cases in 17 states in 2015, but then 149 cases in 39 states in 2016 and 33 cases in 16 states in 2017. And there have been at least 62 cases in 22 states in 2018.
most cases occur in the late summer and early fall
most had symptoms of a preceding viral illness, including respiratory symptoms or diarrhea
brought the Morbidity and Mortality Weekly Report to CDC
investigated the swine influenza virus vaccine incident, when it was thought that some people developed GBS after getting the new swine flu vaccine in 1976
His work saved the lives of hundreds of thousands of people.
Did he ever tell folks to not get a flu shot?
Was he ever concerned about mercury in flu shots?
Considering that Dr. Langmuir died in 1993, before folks became concerned about thimerosal in vaccines, that’s unlikely. That’s especially so considering that the only place you can find these types of quotes are on anti-vaccine websites.
Still, Langmuir was critical of flu shots.
“From this appraisal of the experience in the past three and one-half years, it is apparent that progress in the control of influenza has not been impressive.”
Langmuir et al. on The Epidemiological Basis For The Control Of Influenza
He didn’t think that they worked well enough. Or more importantly, he didn’t think we had enough information about how well they worked.
“Our information regarding the occurrence of influenza is largely qualitative. Schools close, absenteeism increases, medical services become taxed, virus isolations and serological identifications are made in great numbers, and daily accounts appear in our newspapers and on television. We know we have an epidemic and we know its specific cause, but we have few quantitative measures of incidence, age- and sex-specific attack rates, and character and severity of complications. Further- more, we have only crude data regarding mortality. We do not know what proportion of excess deaths occurs among reasonably active and productive citizens in contrast to deaths among persons who are already invalids suffering from severely debilitating pre-existing disease. Despite this serious deficiency we base our recommendations for vaccine use largely on mortality experience. We undertake major efforts to produce influenza vaccine in large amounts, but we have no meaningful information regarding its actual distribution. We do not know to what extent it actually reaches persons at highest risk.”
Langmuir et al. on A Critical Evaluation of Influenza Surveillance
“The availability of potent and effective measles vaccines, which have been tested extensively over the past 4 years, provides the basis for the eradication of measles in any community that will raise its immune thresholds to readily attainable levels.”
Langmuir et al. on Epidemiologic Basis For Eradication Of Measles In 1967
And concerning all that he did in the field of public health, he is certainly not someone that anti-vaccine folks should be quoting.
Did Modern Ventilators Replace the Iron Lung for Folks with Polio?
In addition to thinking that we just change the names of diseases when we want them to go away, some folks think that we don’t see anyone in iron lungs anymore, not because polio has been eliminated, but because modern ventilators simply replaced the iron lung.
Is that true?
The iron lung, invented in 1927, helped people with polio breath.
Unlike most of today’s ventilators, the iron lung is a negative pressure ventilator. In contrast, most modern ventilators, the ones that you see people hooked up to with a tube going down to their lungs, are positive pressure ventilators.
What’s the difference?
A positive pressure ventilator pushes air into your lungs. They are useful when you have a lung disease or simply can’t breath on your own.
When people had polio, there usually wasn’t anything wrong with their lungs – it was their chest muscles and diaphragm that were the problem. So the negative pressure in the iron lung would compress and decompress their chest.
One benefit of the iron lung included that it was less invasive than ventilating someone through a tracheostomy, which became an option in the 1960s. While many new options became available for those needing long term ventilation since then, including noninvasive positive pressure ventilation, some still like to use their iron lungs.
And while it is true that they don’t make them anymore, iron lungs have not disappeared. There are some folks with polio that still use them.
But what if someone developed polio now, would they be put in an iron lung?
No, they wouldn’t. For one thing, they don’t make iron lungs anymore. Instead, they would likely use mouth intermittent positive pressure ventilation.
Still, we don’t see a lot of folks getting diagnosed with polio, needing to use mouth intermittent positive pressure ventilation, instead of iron lungs these days. And that’s because we don’t see a lot of folks getting diagnosed with polio.
What to Know About Polio, Modern Ventilators and Iron Lungs
Although some people with polio are still using their iron lungs, the main reason we don’t see more people with polio needing to use iron lungs or modern ventilators is simply because polio is almost eradicated.
“Before the vaccine was developed, the diagnosis of polio required 24 or more hours of paralysis. After the vaccine release, the diagnosis changed to at least 60 days of paralysis. As you can imagine, cases of polio dropped significantly.”
The Myth That Polio Went Away Because They Changed the Diagnostic Criteria
In 1952, there were 21,000 cases of paralytic polio in the United States.
But were there really?
Didn’t they change the way they diagnosed polio a few years later, right after the first polio vaccines came out, making it less likely that folks would be diagnosed with polio?
The original diagnostic criteria for polio came from the World Health Organization and included:
“Signs and symptoms of nonparalytic poliomyelitis with the addition of partial or complete paralysis of one or more muscle groups, detected on two examinations at least 24 hours apart.”
It changed in 1955 to include residual paralysis 10 to 20 days after onset of illness and again 50 to 70 days after onset.
“In the past children’s paralysis was often not correctly diagnosed as polio. Stool samples need to be analyzed to be able to distinguish paralytic symptoms from Guillain-Barré Syndrome, transverse myelitis, or traumatic neuritis.”
Polio – Data Quality and Measurement
But you coulld’t just use stool samples, as many kids might have recently had non-paralytic polio, and could test positive for polio (false positive test), but have another reason to have paralysis.
“Isolation of poliovirus is helpful but not necessary to confirm a case of paralytic poliomyelitis, and isolation of poliovirus itself does not confirm diagnosis.”
Alexander et al. on Vaccine Policy Changes and Epidemiology of Poliomyelitis in the United States
Since polio causes residual paralysis, the new diagnostic criteria helped to make sure that kids were diagnosed correctly.
Did We Overestimate the Number of Kids with Polio?
Some folks think that since we changed the criteria, we overestimated the number of kids with polio in the years before the vaccine came out.
Most of this idea seems to come from a panel discussion in 1960 by critics of the original polio vaccine, The Present Status of Polio Vaccines, including two, Dr. Herald R. Cox and Dr. Herman Kleinman, who were working on a competing live-virus vaccine.
None in the group were arguing against vaccines, or even really, that the Salk polio vaccine didn’t work at all though. They just didn’t think that it was effective as some folks thought.
“I’ve talked long enough. The only other thing I can say is that the live poliovirus vaccine is coming. It takes time. The one thing I am sure of in this life is that the truth always wins out.”
Dr. Herald R. Cox on The Present Status of Polio Vaccines
Dr. Cox did talk a lot about the oral polio vaccine. He talked about successful trials in Minneapolis, Nicaragua, Finland, West Germany, France, Spain, Canada, Japan, and Costa Rica, etc.
When anti-vaccine folks cherry pick quotes from The Present Status of Polio Vaccines discussion panel, they seem to leave out all of the stuff about how well the oral polio vaccine works.
“Since nothing is available, there seems to be no alternative but to push the use of it. I don’t think we should do so in ignorance, nor too complacently, believing that as long as we have something partially effective there is no need to have something better.”
Dr. Bernard Greenberg on The Present Status of Polio Vaccines
And of course, they did, fairly soon, switch to something better – the Sabin live-virus oral polio vaccine.
Interestingly, using the idea that we changed the diagnostic criteria to make polio go away in an argument about vaccines is known as the Greenberg Gambit.
It tells you something about anti-vaccine arguments, that these folks are misinterpreting something someone said about vaccines almost 60 years ago.
In pushing the idea that polio hasn’t been eliminated, but rather just redefined, they also miss that:
But isn’t polio still around and just renamed as transverse myelitis, Guillain-Barré syndrome (GBS), and aseptic meningitis?
Let’s do the math.
Using the adjusted numbers in the The Present Status of Polio Vaccines discussion, there were at about 6,000 cases of paralytic polio in the United States in 1959.
While 3,000 to 6,000 people in the United States develop Guillain-Barré syndrome each year, the risk increases with age, and it is rare in young kids. Remember, paralytic polio mostly affected younger children, typically those under age 5 years.
“Transverse myelitis can affect people of any age, gender, or race. It does not appear to be genetic or run in families. A peak in incidence rates (the number of new cases per year) appears to occur between 10 and 19 years and 30 and 39 years.”
Transverse Myelitis Fact Sheet
Similarly, transverse myelitis is uncommon in younger children, and there are even fewer cases, about 1,400 a year.
What about aseptic meningitis? That doesn’t usually cause paralysis.
So do the math.
You aren’t going to find that many kids (remember, the incidence was 5-7 per 1,000) under age 5 years who really have “polio,” but instead, because of a worldwide conspiracy about vaccines, are getting diagnosed with transverse myelitis, Guillain-Barré syndrome (GBS), or aseptic meningitis instead.
Anyway, kids with acute flaccid paralysis are thoroughly tested to make sure they don’t have polio. And both transverse myelitis and Guillain-Barré syndrome have different signs and symptoms from paralytic polio. Unlike polio, which as asymmetric muscle atrophy, the atrophy in transverse myelitis and Guillain-Barré syndrome is symmetrical. Also, unlike those other conditions that cause AFP, with polio, nerve conduction velocity tests and electromyography testing will be abnormal. Plus, polio typically starts with a fever. The other conditions don’t. So while these conditions might all be included in a differential diagnosis for someone with AFP, they are not usually that hard to distinguish.
“Each case of AFP should be followed by a diagnosis to find its cause. Within 14 days of the onset of AFP two stool samples should be collected 24 to 48 hours apart and need to be sent to a GPEI accredited laboratory to be tested for the poliovirus.”
Polio – Data Quality and Measurement
But why be so strict on following up on every case of AFP?
It’s very simple.
If you miss a case of polio, then it could lead to many more cases of polio. And that would tmake it very hard to eradicate polio in an area.
If anything, until the establishment of the Global Polio Eradication Initiative (GPEI) in 1988, it is thought that cases of polio and paralytic polio were greatly underestimated in many parts of the world!
And now polio is almost eradicated.
“DR. SABIN: Let us agree, at least, that things are not being brushed aside. Let us say that we might disagree on the extent to which certain things have received study. But I hope that Dr. Bodian realizes that nobody is brushing things aside. I would not have taken the trouble of spending several months studying viremia with different strains in chimpanzees and human volunteers, and viremia produced by certain low temperature mutants to correlate it with their invasive capacity, if I were merely brushing it aside.”
Live Polio Vaccines – Papers Presented and Discussions Held at the First International Conference on Live Poliovirus Vaccines
If they redefined how paralytic polio was diagnosed in 1955 as part of a conspiracy to make it look like the polio vaccines were working, then why did the number of cases continue to drop into the 1960s?
Shouldn’t they have just dropped in 1955 and then stayed at the same lower level?
And why don’t any of the folks with other conditions that cause paralysis, like transverse myelitis and Guillain-Barré syndrome (GBS) ever have polio virus in their system when they are tested?
Also, if the renaming theory explains why the polio vaccine didn’t work, then why do anti-vaccine folks also need to push misinformation about DDT and polio?
What to Know About Polio Myths and Conspiracies
The near eradication of polio from the world is one of the big success stories of the modern era, just as those who push the idea that has all been faked is a snapshot of society at one of our low points.
Well, unlike most other vaccines, the meningococcal B vaccines are not thought to decrease nasal carriage of the meningococcal B bacteria. So if you are vaccinated and an asymptomatic carrier of the bacteria, you could theoretically spread it to someone else, as could someone who is unvaccinated.
Still, the MenB vaccines can protect you from getting actual meningococcal B disease, and if you don’t have meningococcemia or meningococcal meningitis, you won’t expose and spread it to someone else. That’s why the MenB vaccines are especially useful in outbreak situations.
Any others? After all, Dr. Bob did say that “most vaccines don’t prevent the spread of a disease.”
Vaccines That Don’t Prevent the Spread of a Disease
There are a few other examples of vaccines that don’t prevent the spread of a disease.
“I also warn them not to share their fears with their neighbors, because if too many people avoid the MMR, we’ll likely see the diseases increase significantly.”
Dr. Bob Sears in The Vaccine Book
Of course, any vaccine that is delayed or skipped won’t work to prevent the spread of a disease.
Just like they are seeing measles outbreaks and deaths now, because of low vaccination rates, in Ukraine there were 17,387 cases of diphtheria and 646 deaths from 1992 to 1997. Also high, were cases of measles (over 23,000 cases in 1993) and pertussis (almost 7,000 cases in 1993).
And because of waning immunity, vaccines don’t do as good a job of preventing the spread of pertussis and mumps as we would like. Still, that’s only when the vaccines don’t work, and even then, as Dr. Bob says, they do work to reduce the severity of symptoms. During recent mumps outbreaks, the rates of complications are far below historical levels. The same is true for pertussis.
We typically see the same thing with flu. Even when the flu vaccine isn’t a good match or isn’t as effective as we would like, it still has a lot of benefits, including reducing your risk of dying.
“IPV induces very low levels of immunity in the intestine. As a result, when a person immunized with IPV is infected with wild poliovirus, the virus can still multiply inside the intestines and be shed in the faeces, risking continued circulation.”
Inactivated poliovirus vaccine
Does the fact that IPV, the inactivated polio vaccine, can sometimes lead to infections and shedding mean that it doesn’t prevent infections?
Of course not!
“IPV triggers an excellent protective immune response in most people.”
Inactivated poliovirus vaccine
Most people vaccinated with IPV will be immune, won’t get wild polio, and so won’t be able to get anyone else sick.
“Vaccines reduce disease by direct protection of vaccinees and by indirect protection of nonimmune persons. Indirect protection depends on a reduction in infection transmission, and hence on protection (immunity) against infection, not just against disease. If a vaccine were to protect only against disease, and not at all against infection, then it would have no influence on infection transmission in the community and there would be no indirect protection (vaccination of one person would have no influence on any others in the community). It would be possible to reduce disease with such a vaccine but not to eradicate the infection.”
But because IPV doesn’t provide indirect protection, we still use OPV in parts of the world where polio is more of a problem.
Vaccines work. Even the few that don’t prevent the spread of infections, still help to reduce disease.
What’s the Difference Between Infections and Disease?
Wait, is there a difference between infection and disease?
Yes there is, something that Dr. Bob, who actually wrote a book about vaccines, seems to have overlooked.
An infection is simply the presence of a virus, bacteria, or other organism in your body.
A disease, on the other hand, is a virus or bacteria in your body causing signs and symptoms.
All vaccines work to prevent disease, or at least they do when you actually get vaccinated.
A very few don’t prevent infections and the spread of infections, but that is not a good reason to skip or delay your child’s vaccines. In fact, it is one of the reasons why it is important to have high vaccination rates! Even natural infections don’t always keep you from becoming asymptomatic carriers that can infected others. Many people who have natural typhoid (remember Typhoid Mary?) and hepatitis B infections go on to become chronic carriers without any symptoms, but still able to infect others.
If you understand that a few vaccines don’t prevent the spread of infections, then you should understand that you can’t hide in the herd and expect to be protected, even though most folks around you are vaccinated.
What to Know About Vaccines and the Spread of Disease
Despite what Dr. Bob says, almost all vaccines work to prevent the spread of disease and infections, at least they do when you get your kids vaccinated.