We should know that vaccine-preventable diseases were rarely mild, natural immunity comes at a cost, and that those who died from smallpox, diphtheria, measles, and polio aren’t around to talk about their experiences on Facebook (survivorship bias).
We should never forget that vaccine-preventable diseases were once big killers, and the only reason some folks have grown to fear the side effects of vaccines more than the diseases they prevent, is because we don’t see those diseases very much any more. If more people skip or delay getting vaccinated, we will though.
Meningitis is classically defined as an inflammation of the membranes that cover the brain and spinal cord, and it can be caused by:
viruses – also called aseptic meningitis, it can be caused by enteroviruses, measles, mumps, and herpes, etc.
bacteria – Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes, Haemophilus influenzae type b (Hib), Group B strep
a fungus – Cryptococcus, Histoplasma
parasites – uncommon
amebas – Naegleria fowleri
Surprisingly, there are even non-infectious causes of meningitis. These might be include side-effects of a medication or that the child’s meningitis is a part of another systemic illness.
What to Do If Your Child Is Exposed to Meningitis
While meningitis can be contagious, it greatly depends on the type of meningitis to which they are exposed as to whether or not your child is at any risk.
So while the general advice is to “tell your doctor if you think you have been exposed to someone with meningitis,” you should try and gather as much information as you can about the exposure.
This information will hopefully include the type of meningitis they were exposed to, specifically if it was bacterial or viral, the exact organism if it has been identified, and how close of an exposure it was – were they simply in the same school or actually sitting next to each other in the same room.
For example, while the CDC states that “people who are close contacts of a person with meningococcal or Haemophilus influenzae type b (Hib) meningitis are at increased risk of getting infected and may need preventive antibiotics,” they also state that “close contacts of a person with meningitis caused by other bacteria, such as Streptococcus pneumoniae, do not need antibiotics.”
And you often don’t need to take any preventive measures if you are exposed to someone with viral meningitis.
While that might sound scary, it is basically because you typically aren’t at big risk after this kind of exposure. You could get the same virus, but the chances that it would spread and also cause meningitis are very unlikely.
Other types of meningitis, like primary amebic meningoencephalitis (PAM) and fungal and parasitic meningitis aren’t even contagious.
The Histoplasma fungus spreads from bird or bat droppings, for example, not from one person to another.
And parasites typically spread from ingesting raw or undercooked food, or in the case of Baylisascaris procyonis, from ingesting something contaminated with infectious parasite eggs in raccoon feces.
What to Do If Your Unvaccinated Child Is Exposed to Meningitis
Vaccines can prevent a number of different types of meningitis.
You should immediately call your pediatrician or local healthy department, because they might need:
antibiotics (usually rifampin, ciprofloxacin, or ceftriaxone) if the meningitis was caused by Neisseria meningitidis
antibiotics (rifampin) if the meningitis was caused by Haemophilus influenzae type b (Hib)
The availability of these antibiotics isn’t a good reason to skip or delay getting vaccinated though, as you won’t always know when your kids have been exposed to meningitis and not all types of vaccine-preventable meningitis can be prevented with antibiotics.
Of course, getting fully vaccinated on time is the best way to prevent many of these types of meningitis and other life-threatening diseases.
What to Do If Your Vaccinated Child Is Exposed to Meningitis
Even if your child is vaccinated, they might still need preventative antibiotics if they are exposed to someone with Hib or meningococcal meningitis, as vaccines are not 100% effective.
“Regardless of immunization status, close contacts of all people with invasive meningococcal disease , whether endemic or in an outbreak situation, are at high risk of infection and should receive chemoprophylaxis.”
AAP Red Book on Meningococcal Infections
This is especially true if they are not fully vaccinated.
Remember, to be fully vaccinated against Haemophilus influenzae type b, kids get a 2 or 3 dose primary series of the Hib vaccine when they are infants and a booster dose once they are 12 months old.
In the case of exposure to Hib meningitis, antibiotic prophylaxis would be recommended if:
the child is fully vaccinated, but there is a young child, under age 4 years, in the house who is unvaccinated or only partially vaccinated
the child is fully vaccinated, but there is another child in the house who is immunocompromised
the child is only partially vaccinated and under age 4 years
there is an outbreak in a preschool or daycare, with 2 or more cases within 60 days
And anyone exposed to someone with meningococcal meningitis should likely get antibiotics (chemoprophylaxis), even if they are fully vaccinated.
Talk to your pediatrician or local health department if your child is exposed to meningitis and you aren’t sure what to do, whether or not your child has been vaccinated.
What to Know About Getting Exposed to Meningitis
Learn what to do if your child is exposed to someone with meningitis, especially if they are unvaccinated, or have been exposed to someone with Hib meningitis or meningococcal disease.
The idea of herd immunity has been around since at least 1923 and became used to describe “the indirect protection afforded to individuals by the presence and proximity of others who are immune.”
That’s not much different from how the CDC defines herd immunity today:
A situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely. Even individuals not vaccinated (such as newborns and those with chronic illnesses) are offered some protection because the disease has little opportunity to spread within the community.
Also called community immunity, it is often misunderstood by folks in the anti-vaccine movement.
Challenging the Concept of Herd Immunity
That the idea of herd immunity is being challenged is not new.
“Along with the growth of interest in herd immunity, there has been a proliferation of views of what it means or even of whether it exists at all.”
Paul E. M. Fine Herd Immunity: History, Theory, Practice
It is mostly because we live in open communities that don’t mix randomly.
Keep in mind that the best model for herd immunity is a randomly mixing closed community – “one in which the probability of contact within any time interval is the same for every choice of two individuals in the population.”
Again, that doesn’t mean herd immunity doesn’t work.
It just means we can expect to see some outbreaks when someone in a well vaccinated community visits another community with lower vaccination levels and more disease, gets sick, and returns.
“However, within the population of a community, there may be pockets of susceptibles, either because prior epidemics have failed to spread into the group or because they have not accepted immunization.”
John P. Fox Herd Immunity
You must also consider the size of the community when thinking about herd immunity, for example, a family, school, neighborhood, or city, versus the entire state. So you can have herd immunity levels of protection at the state or city level because of high average vaccination levels, but pockets of susceptibles who live in the same neighborhood or go to the same school can mean that you don’t have herd immunity in those places, leading to outbreaks.
“Hib vaccine coverage of less than 70% in the Gambia was sufficient to eliminate Hib disease, with similar findings seen in Navajo populations.”
RA Adegbola Elimination of Hib disease from The Gambia after…
Lastly, there is not one herd immunity level for all diseases. It is a separate threshold for each and every disease, depending on how easily it spreads, how many people are already immune, how long immunity lasts, if there is a vaccine, and the effectiveness of the vaccine, etc. That means that a community can have herd immunity for Hib and polio, but not the flu, and for rubella and measles, but not pertussis.
What happened in The Gambia is a great example of herd immunity. After introducing a three dose primary Hib immunization schedule (no booster dose), rates of Hib meningitis quickly went from 200 per 100,000 to none. A few years later, there were 6 cases of Hib meningitis in mostly vaccinated children (no booster dose) and in the majority of cases, “close contacts had a history of frequent or recent travel to Senegal, a neighboring country with strong kinship links with The Gambia and where vaccination against Hib was not introduced” until the following year.
With a Hib meningitis rate of 3 per 100,000, they are still far below pre-vaccine levels of disease, and their situation doesn’t mean that herd immunity isn’t real, as you will understand once you review these myths about herd immunity.
Myths About Herd Immunity
What are some common myths about herd immunity?
that natural immunity is better than getting vaccinated. Not True.Natural immunity often comes with a price. Remember, many vaccine-preventable diseases are life-threatening, even in this age of modern medicine.
you can just hide in the herd. Not True. “Freeloaders” can gamble and hope that their intentionally unvaccinated kids won’t get a vaccine-preventable disease, but it won’t always work. There is a risk to “free-riding, in which individuals profit from the protection provided by a well-vaccinated society without contributing to herd immunity themselves.”
most adults aren’t immune because they haven’t been vaccinated or don’t get boosters, but since we aren’t seeing that many outbreaks, herd immunity itself must be a myth. Not True.Adults were either born in the pre-vaccine era and likely have natural immunity or were born in the vaccine era and are vaccinated and immune. But again, herd immunity is disease specific, so when we talk about herd immunity for measles, it doesn’t matter if they have immunity against hepatitis A or Hib. And adults get few boosters or catch-up vaccines. Also, some vaccines, like Hib and Prevnar, have indirect effects, protecting adults even though they aren’t vaccinated because vaccinated kids are less likely to become infectious.
most vaccines wear off too soon to provide long lasting protection for herd immunity to be real. Not True. While waning immunity is a problem for a few diseases, like pertussis and mumps, and you need boosters for others, like tetanus, vaccine induced immunity is typically long lasting and often life-long.
herd immunity wasn’t developed by observing immunized people, it was all about natural immunity. Not True. The first experiments about herd immunity by Topley and Wilson in 1923 involved vaccinated mice. Ok, they weren’t immunized people, but it wasn’t just about natural immunity! And much earlier, in 1840, it was noted that “smallpox would be disturbed, and sometimes arrested, by vaccination, which protected a part of the population.” That’s herd immunity he was talking about.
herd immunity is not a scientifically validated concept. Not True. It has been well studied for almost 100 years.
if herd immunity was real, diseases would be eradicated once you reached herd immunity levels. Not True. Reaching herd immunity levels simply starts a downward trend in disease incidence. A little more work has to be done at the final stages of eradication, like was done for smallpox and is being done for polio.
natural immunity causes much of the decrease in mortality from a disease in the developed world, even before a vaccine is introduced. Not True. While it is certainly true that there was a big drop in mortality in the first half of the 20th century for most conditions because of improvements in sanitation, nutrition, and medical science, it was not a consequence of natural herd immunity. And we continue to see significant levels of mortality and morbidity for many diseases in the modern era, especially for those that can’t yet be prevented by a vaccine, like RSV, West Nile Virus, and malaria, etc.
vaccines aren’t 100% effective, so herd immunity can’t really work. Not True. Part of the equation to figure out the herd immunity threshold for a disease takes into account the effectiveness of a particular vaccine.
folks with medical exemptions for vaccines put the herd at risk just the same as those who intentionally skip vaccines. Not True. Children and adults with medical exemptions, including immune system problems, those getting treatments for cancer, and other true medical exemptions don’t have a choice about getting vaccinated.
So, like other anti-vaccine myths, none of the herd immunity myths you may have heard are true.
That makes it hard to understand why Dr. Russel Blaylock goes so far as to say “that vaccine-induced herd immunity is mostly myth can be proven quite simply.” Does he just not understand herd immunity? That is certainly a possibility, because “although herd immunity is crucial for the elimination of infectious diseases, its complexity and explicit relationship to health politics cause it to remain under-explained and under-used in vaccine advocacy. ”
He is also really big into pushing the idea that adults have no or little immunity, because when he was in medical school, he was “taught that all of the childhood vaccines lasted a lifetime,” but it has now been discovered that “most of these vaccines lost their effectiveness 2 to 10 years after being given.”
The thing is, Blaylock graduated medical school in 1971, when the only vaccines that were routinely used were smallpox (routine use ended in 1972), DPT, OPV, and MMR (it had just become available as a combined vaccine in 1971). Of these, it was long known that smallpox, diphtheria, and tetanus didn’t “last a lifetime,” and the live vaccines OPV and MMR, except for the mumps component, actually do.
Blaylock, like most anti-vaccine folks who push myths about herd immunity, is plain wrong. And like most anti-vaccine myths, using herd immunity denialism to convince parents that it is okay to skip or delay vaccines puts us all at risk for disease.
What To Know About Herd Immunity Myths
Herd immunity is not junk science or a false theory. Herd immunity is real, it works, and explains how people in a community are protected from a disease when vaccination rates are above a certain threshold.