Tag: eradication

Why Are the DPT and OPV Vaccines Still Used in Some Countries?

As most folks know, neither the DPT nor OPV vaccines are used in the United States.

Pope Francis helped launch a polio vaccine campaign when he visited Mexico in 2016.
Pope Francis helped launch a polio vaccine campaign when he visited Mexico in 2016.

That they are still used in other countries likely raises some questions for those folks that get them.

Why Are the DPT and OPV Vaccines Still Used in Some Countries?

As I am sure you have guessed, there is no conspiracy about the continued use of these vaccines in other parts of the world. We aren’t getting rid of old stocks of vaccines or using cheaper vaccines in poorer parts of the world.

So what’s the reason?

To understand why they are still used in other countries, it helps to understand why they aren’t used here.

Remember that the DPT vaccine, which protects folks against diphtheria, pertussis, and tetanus, came under attack in the 1970s and 80s as some folks blamed the vaccine for causing vaccine injuries, including seizures and encephalopathy. It didn’t, but we still got a new vaccine, DTaP, which doesn’t seem to work as well.

“Although concerns about possible adverse events following their administration have led to the adoption of acellular pertussis vaccines in some countries, whole-cell pertussis vaccines are still widely produced and used globally in both developed and developing countries. Whole-cell pertussis vaccines that comply with WHO requirements, administered according to an optimal schedule have a long and successful record in the control of whooping cough. Furthermore, the excellent efficacy of some currently available whole-cell pertussis vaccine has also been shown, not only in recent clinical trials, but also on the basis of the resurgence of disease where vaccination has been interrupted or when coverage has markedly decreased. Therefore, WHO continues to recommend whole-cell pertussis vaccines for use in national immunization programmes.”

WHO on Recommendations for whole-cell pertussis vaccine

The WHO now recommends that if countries do switch to DTaP,  the acellular pertussis vaccine, they should be prepared to add additional periodic booster doses and immunizations during pregnancy, which may still “may not be sufficient to prevent resurgence of pertussis.”

The OPV vaccine, on the other hand, was replaced because it can rarely cause vaccine-associated paralytic polio (VAPP) and circulating vaccine-derived polio virus (cVDPV). Of course, it does it at much lower rates than wild polio virus, so until polio is well controlled, the benefit of using OPV outweighs the risk. In addition to being less expensive and easier to use, OPV has the benefit over IPV of providing better herd immunity.

At some point, as we did in the United States in 2000, countries make a switch to the IPV vaccine.

In 2016, remaining countries that use OPV switched from trivalent OPV to bivalent OPV, because wild polio virus type 2 was eradicated in 1999. Once the remaining two types are eradicated, we can stop using the OPV vaccine altogether.

Until then, countries either use:

  • OPV plus one dose of IPV
  • sequential IPV-OPV schedules – high vaccine coverage and low risk of wild polio importation
  • IPV only schedules – sustained high vaccine coverage and very low risk of wild polio importation

So there is no conspiracy. These vaccines are safe and they work.

Without them, there would be over:

  • 1.3 million pertussis related deaths each year
  • 600,000 cases of paralytic polio each year

With most of these cases affecting young children.

More on the Continued Use of DPT and OPV Vaccines

The Hospital Rock Engravings of Farmington, Connecticut

Vaccines are a lot safer than they used to be in the old days.

No, I’m not talking about the “crude brew” that was the original DTP vaccine.

This older vaccine used more antigens than the DTaP vaccine that replaced it, so could cause more side effects. Even before that though, there was less oversight of vaccine manufacturers in the early 20th century. This could lead to vaccines that were contaminated or which simply didn’t work.

That certainly was a problem with the early smallpox vaccine, which is typically considered to be the most dangerous vaccine ever routinely used.

Variolation and Smallpox

But even before the smallpox vaccine was developed by Edward Jenner in 1796, we had variolation.

While the smallpox vaccine involved the cowpox virus, variolation actually infected someone with smallpox. The idea was to give the person a milder form by exposing them to a weaker, or attenuated, form of the virus.

They got this weakened virus from the smallpox scabs of someone who had already recovered and:

  • blowing dried smallpox scabs into their nose
  • applying pus from smallpox scabs to a small puncture wound on their skin

Variolation worked, giving the person immunity to smallpox – if they survived.

Unfortunately, about 1 to 3% of people who underwent variolation died.

And people who had recently undergone variolation could be contagious, leading to smallpox epidemics.

So why did folks undergo variolation if they had a chance of dying from the procedure?

It’s simple.

A natural smallpox infection was so much more deadly. Up to 30% of people who got smallpox died, and many people eventually got caught up in the regular smallpox epidemics that plagued people in the pre-vaccine era.

The Hospital Rock Engravings of Farmington, Connecticut

We don’t have to worry about smallpox anymore.

Well, not about natural smallpox infections, since smallpox was eradicated back in 1980.

And there are many other diseases that we get vaccinated against, with it being extremely easy to get that protection, especially compared to what folks did in the old days.

Do you know how far folks went to make variolation safer?

“Every year, thousands undergo this operation, and the French Ambassador says pleasantly, that they take the small-pox here by way of diversion, as they take the waters in other countries. There is no example of any one that has died in it, and you may believe I am well satisfied of the safety of this experiment, since I intend to try it on my dear little son. I am patriot enough to take the pains to bring this useful invention into fashion in England…”
Lady Mary Wortley Montagu On Small Pox in Turkey (1717)

They actually went to smallpox hospitals to get vaccinated, remaining in quarantine for up to three weeks so that they wouldn’t get others sick.

In Farmington, Connecticut, two doctors established the Todd-Wadsworth Smallpox Hospital and had a lot of success with variolation.

Patients were no longer starved before inoculation, and many had begun to doubt the efficacy and safety of vomiting, sweats, purges, mercurials (toxic mercury salts such as calomel), and bleeding which had previously weakened both inoculees and those who “took the pox in the natural way.”

Charles Leach, MD on Hospital Rock

There, up to 20 patients at a time stayed in quarantine to get variolated, as a smallpox epidemic hit nearby Boston.

Patients engraved their name on Hospital Rock in the late 1700s near Farmington.
Patients engraved their name on Hospital Rock in the late 1700s near Farmington. Photo by Keith Wilkens

Between 1792 and 1794, many who got variolated wrote their names on what is now known as Hospital Rock.

“Many have supposed that the names on this rock were those who had did of the small-pox, but this is a great mistake. Every name on the rock is that of a person who was living when the name was placed there. Norris Stanley lived to own ships which were captured in the war of 1812 by Algerian pirates and still later to receive from the United States an indeminity therefor amounting to a large sum.”

James Shepard on The Small Pox Hospital Rock

The nearby town of Durham seemed to go a different way.

Instead of an inoculation hospital, they had a pest house to quarantine folks with natural smallpox infections.

Adding to the history of smallpox in Connecticut – a smallpox burying ground in Guilford.

Why wasn’t variolation popular everywhere? Folks didn’t have to wait for the first vaccine for the anti-vaccine movement to get started.

What to Know About Smallpox and the Hospital Rock Engravings

Hundreds of people got safely inoculated against smallpox and left their names on Hospital Rock near Farmington, Connecticut just before Edward Jenner discovered the first smallpox vaccine.

More on the Hospital Rock Engravings

Is the Anti-Vaccine Movement Growing?

Boston Reverend Cotton Mather  actively promoted smallpox inoculation during a local epidemic.
Boston Reverend Cotton Mather actively promoted smallpox inoculation during a local epidemic.

We often have to remind people that the anti-vaccine movement didn’t start with Bob Sears, or Jenny McCarthy, or even with Andy Wakefield.

Did you know that the Reverend Cotton Mather’s house was bombed in Boston in 1721? Well, someone through a bomb through his window. Fortunately, it didn’t go off.

That’s 77 years before Jenner developed his smallpox vaccine!

What was Mather doing?

He had started a smallpox variolation program. He was trying to protect people in Boston from smallpox during one of the most deadly epidemics of the time.

So essentially, the anti-vaccine movement started before we even had real vaccines…

Is the Anti-Vaccine Movement Growing?

You see reports of more and more outbreaks of vaccine-preventable diseases, hear about new vaccine laws and mandates, and depending on who your friends are, may see a lot of anti-vaccine articles and vaccine injury stories getting shared on Facebook.

You have probably even heard about pediatricians firing families who refuse to vaccinate their kids.

So what’s the story?

Is the anti-vaccine movement growing?

Is there a growing resistance among parents to getting their kids vaccinated?

“Parents are taking back the truth. It is my expectation that this crack in the dam will serve to sound an alarm. To wake women up. To show them that they have relinquished their maternal wisdom, and that it is time to wrest it back.”

Kelly Brogan, MD

Is the world finally “waking up to the dangers of vaccines,” like many anti-vaccine experts have been claiming for years and years?

The Anti-Vaccine Movement is not Growing

Many people will likely tell you that the anti-vaccine is in fact growing.

You can read it in their headlines:

  • The worrying rise of the anti-vaccination movement
  • Will 2017 be the year the anti-vaccination movement goes mainstream?
  • Pediatricians calling anti-vaccine movement a growing problem
  • There’s Good Evidence That The Anti-Vaccine Movement Is Growing
  • I was skeptical that the anti-vaccine movement was gaining traction. Not anymore.

But the anti-vaccine movement is not necessarily growing.

The overwhelming majority of parents and adults are fully vaccinated.

What we do have is a very vocal minority of people who do their best to push misinformation and conspiracy theories about vaccines and vaccine dangers, and not surprisingly, they have some new ways to do it. Unfortunately, they use their anti-vaccine talking points to scare vaccine hesitant parents and those who might now be on the fence about vaccines to sometimes delay or skip some vaccines.

Most parents do their research though, don’t jump on the anti-vaccine bandwagon, and know that vaccines work, vaccines are safe, and vaccines are necessary.

The Anti-Vaccine Movement is Changing

A lot about the anti-vaccine movement hasn’t changed over the last 100 plus years.

Many early critics of vaccines were alternative medicine providers, including homeopaths and chiropractors, just like we see today. And like they do today, they argued that vaccines didn’t work, vaccines were dangerous, and that vaccines weren’t even necessary.

alicia-silverstone

The big difference?

Unlike when Lora Little, at the end of the 19th century, had to travel around the country to distribute her anti-vaccine pamphlet, Crimes of the Cowpox Ring, anti-vaccine folks can now just tweet or post messages on Facebook. It is also relatively easy to self-publish an anti-vaccine book and sell it on Amazon, put up your own anti-vaccine website, post videos on YouTube, or even make movies.

“Whatever you think about Andrew Wakefield, the real villains of the MMR scandal are the media.”

Ben Goldacre on The MMR story that wasn’t

Fortunately, all of that is balanced by something they don’t have anymore.

No, it’s not science. That was never on their side.

It’s that the media has caught on to the damage they were doing and isn’t as likely to push vaccine scare stories anymore.

Explaining the Popularity of the Anti-Vaccine Movement

The anti-vaccine movement has always been around and they are likely not going anywhere, whether or not they are growing.

Looking at the history of the anti-vaccine movement, it is clear that they have their ups and downs, times when they are more or less popular, but they are always there.

“By the 1930s… with the improvements in medical practice and the popular acceptance of the state and federal governments’ role in public health, the anti-vaccinationists slowly faded from view, and the movement collapsed.”

Martin Kaufman The American Anti-Vaccinations and Their Arguments

Why so many ups and downs?

As more people are vaccinated and diseases disappear, they forget how bad those diseases are, skip or delay getting their vaccines, and trigger outbreaks.
As more people are vaccinated and diseases disappear, they forget how bad those diseases are, skip or delay getting their vaccines, and trigger outbreaks. Chart by WHO

It is easily explained once you understand the evolution of our immunization programs, which generally occurs in five stages:

  1. pre-vaccine era or stage
  2. increasing coverage stage – as more and more people get vaccinated and protected, you pass a crossover point, where people begin to forget just how bad the diseases really were, and you start to hear stories about “mild measles” and about how polio wasn’t that bad (it usually wasn’t if you didn’t get paralytic polio…)
  3. loss of confidence stage – although vaccine side effects are about the same as they always were, they become a much bigger focus because you don’t see any of the mortality or morbidity from the diseases the vaccines are preventing. It is at this point that the anti-vaccine movement is able to be the most effective.
  4. resumption of confidence stage – after the loss of confidence in stage three leads to a drop in vaccine coverage and more outbreaks of a vaccine-preventable disease, not surprisingly, more people understand that vaccines are in fact necessary and they get vaccinated again. It is at this point that the anti-vaccine movement is the least effective, as we saw after outbreaks of pertussis in the UK in the 1970s and measles more recently. You also see it when there is a report of an outbreak of meningococcal disease on a college campus or a child dying of the flu on the local news, etc.
  5. eradication stage – until we get here, like we did when smallpox was eradicated, the anti-vaccine movement is able to cycle through stages two to four, with ups and downs in their popularity,

So the anti-vaccine movement is able to grow when they have the easiest time convincing you that the risks of vaccines (which are very small) are worse than the risks of the diseases they prevent (which are only small now, in most cases, because we vaccinate to keep these diseases away, but were life-threatening in the pre-vaccine era).

“As vaccine use increases and the incidence of vaccine-preventable diseases is reduced, vaccine-related adverse events become more prominent in vaccination decisions. Even unfounded safety concerns can lead to decreased vaccine acceptance and resurgence of vaccine-preventable diseases, as occurred in the 1970s and 1980s as a public reaction to allegations that the whole-cell pertussis vaccine caused encephalopathy and brain damage. Recent outbreaks of measles, mumps, and pertussis in the United States are important reminders of how immunization delays and refusals can result in resurgences of vaccine-preventable diseases.”

Paul Offit, MD on Vaccine Safety

Fortunately, most parents don’t buy into the propaganda of the anti-vaccine movement and don’t wait for an outbreak to get their kids vaccinated and protected. They understand that you can wait too long.

The bottom line – except for pockets of susceptibles and clusters of unvaccinated kids and adults, most people are vaccinated. If the anti-vaccine does grow, it eventually gets pulled back as more kids get sick.

What to Know about the Growing Anti-Vaccine Movement

Although they may have an easier time reaching more people on Twitter, Facebook, YouTube, and with Amazon, the overwhelming majority of parents vaccinate their kids and aren’t influenced by what some people think is a growing anti-vaccine movement.

More on the Growing Anti-Vaccine Movement

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Myths About Polio and Acute Flaccid Paralysis

Polio is one of the most well known causes of acute flaccid paralysis.

Although most people with polio infections have no symptoms at all, or just have a very mild illness, with a sore throat and a low grade fever, a small percentage can develop:

  • a loss of superficial reflexes
  • severe muscle aches and spasms in their limbs or back
  • an asymmetrical flaccid paralysis with diminished deep tendon reflexes

This acute flaccid paralysis only affects the child’s strength in the affected muscle groups – there is no loss of sensation. The severity of the symptoms and the disease depends on which muscles are affected the most. If it is just your legs, then you will have trouble walking. On the other hand, if it affects your chest, then you might not be able to breath, unless you are put on a ventilator (iron lung).

Acute Flaccid Paralysis

Thinking about it in the context of polio, it becomes easy to understand acute flaccid paralysis or AFP.

It is the sudden onset (acute) of a flaccid (floppy or poor muscle tone) paralysis (weakness or inability to move) of one or more muscles.

But what many people don’t understand, is that in addition to polio, there are many more non-polio causes of AFP.

Non-Polio AFP

Many of us got a crash course in non-polio acute flaccid paralysis (NP-AFP) a few years ago when we started hearing reports of kids developing polio-like paralysis in 2014. Now thought to be caused by enterovirus D68 infections (EV-D68), the paralysis followed respiratory tract infections in many of the affected children. All together, at least 120 children in 34 states developed acute flaccid paralysis that year.

Interestingly, EV-D68 is one of more than 100 non-polio enteroviruses. The virus that causes hand, foot, and mouth disease, coxsackievirus A16, is another. Others cause pinkeye, meningitis, or encephalitis.

Keep in mind that many other viruses and conditions can cause non-polio AFP too, including:

  • Guillian-Barré syndrome
  • toxins (botulism)
  • tumors
  • transverse myelitis
  • traumatic neuritis
  • other infections, including novel enterovirus C105, a non-polio enterovirus, and even tick-borne (Lyme disease) and mosquito-borne (Japanese encephalitis) infections

How do you determine the cause and how do you know it isn’t polio?

These kids with AFP typically have extensive testing to determine what is causing their AFP, including an MRI, antibody tests, and testing of their cerebrospinal fluid, etc. Although it isn’t always possible to identify a cause, you can at least rule out many potential suspects, like trauma, polio, and other infections.

Myths About Polio and Acute Flaccid Paralysis

Some folks don’t believe in non-polio AFP.

They believe that polio never really disappeared because vaccines don’t really work and that polio was simply renamed to, you guessed it, acute flaccid paralysis.

“Unbeknownst to most doctors, the polio-vaccine history involves a massive public health service makeover during an era when a live, deadly strain of poliovirus infected the Salk polio vaccines, and paralyzed hundreds of children and their contacts. These were the vaccines that were supposedly responsible for the decline in polio from 1955 to 1961! But there is a more sinister reason for the “decline” in polio during those years; in 1955, a very creative re-definition of poliovirus infections was invented, to “cover” the fact that many cases of ”polio” paralysis had no poliovirus in their systems at all. While this protected the reputation of the Salk vaccine, it muddied the waters of history in a big way.”

Suzanne Humphries, MD on Smoke, Mirrors, and the “Disappearance” Of Polio

What’s their evidence?

A rise in cases of non-polio AFP in India since 1997.

How do we know that there has been a rise in non-polio AFP cases in India since 1997?

It’s very simple and explains why there isn’t any data on before that 1997. 

As part of the strategy to eliminate polio in that country, starting in 1997, all cases of AFP started getting tested for polio. It was a way to track the effectiveness of the immunization program. If you were seeing too many cases of AFP caused by polio, then not enough people were getting vaccinated. On the other hand, if you weren’t seeing any cases of AFP in an area, then the testing and surveillance probably wasn’t getting none, since there will always be some cases of non-polio AFP.

Unfortunately, they found many cases to track. And the cases kept increasing, although more and more, they weren’t being caused by polio. At least not by live polio virus.

Were they caused by the polio vaccine?

In some cases, yes. It is well known that the live polio vaccine can rarely cause VAPP and cVDPV.

By 2015, after India was declared free of polio (the last case was in 2011), none of those cases of AFP were found to be caused by wild polio though. And India hasn’t had a case of cVDPV since 2010.

Why the increase in cases of non-polio AFP? It certainly isn’t because of Suzanne Humphries’ polio virus renaming conspiracy or any other anti-vaccine conspiracy involving the polio vaccine itself.

The 'data' that Susanne Humphries uses to try and make her case about AFP neglects to mention that in the pre-vaccine era, polio paralyzed 500 to 1,000 children in India each day! Those 180,000 to 365,000 cases of paralysis wouldn't fit on her chart though...
The ‘data’ that Susanne Humphries uses to try and make her case about AFP neglects to mention that in the pre-vaccine era, polio paralyzed 500 to 1,000 children in India each day! Those 180,000 to 365,000 cases of paralysis wouldn’t fit on her chart though…
If we simply renamed polio to non-polio AFP, why did the numbers drop for so long and then slowly start to increase? Shouldn’t it have been a rapid crossover?

More importantly,  why are the case of paralysis from non-polio AFP so much lower than the pre-vaccine era cases of AFP from polio?

And how come we rarely see large outbreaks of AFP like we did in the pre-vaccine era?

Sure, 120 kids in the EV-D68 non-polio AFP outbreak of 2014 is way more than any of us would like to see, but it is tremendously less than what we used to see in the pre-vaccine era from polio.

“Poliomyelitis is one of the important emergent viral diseases of the twentieth century… At its height, from 1950–1954, poliomyelitis resulted in the paralysis of some 22,000 U.S. citizens each year… Many thousands were left permanently disabled by the disease, while many others suffocated as a consequence of respiratory paralysis.”

Barry Trevelyan on the The Spatial Dynamics of Poliomyelitis in the US

While anti-vaccine conspiracy theories about AFP are as easy to dismiss as all of the rest they bring up,  what is behind the rise in AFP in some areas of the world?

Although one study that was published in Pediatrics, “Trends in Nonpolio Acute Flaccid Paralysis Incidence in India 2000 to 2013,” did find a correlation between the use of the OPV vaccine and the incidence of non-polio AFP, many experts think the rise is a result of better screening. Also, once polio gets under control, other more neglected diseases start getting more attention, like enteroviral infections. Not surprisingly, other parts of the world have had the same experience.

There is also the fact that in 2005, the Global Poliomyelitis Eradication Initiative began “to cast a wider net for poliovirus detection and to maximize sensitivity so that every poliomyelitis case is detected.” Why? If even a single case was missed, it could lead to continued outbreaks and would get in the way of polio elimination in the country.

“This large increase in NP-AFP cases, which represent AFP cases caused by agents other than poliovirus, probably reflects the excellent implementation of the expanded definition of AFP and highly sensitive surveillance and detection methods used by NPSP in India from 2005 onwards…”

C. Durga Rao on Nonpolio Acute Flaccid Paralysis in India

So did the polio vaccine recently cause 53,000 paralysis victims in India?

No. 

The polio vaccine has worked to get us on the brink of eradicating polio though.

What To Know About Acute Flaccid Paralysis

Acute flaccid paralysis can be caused by the polio virus, but non-polio acute flaccid paralysis becomes a more important cause once polio is eliminated in a region.

More About Acute Flaccid Paralysis

cVDPV

Circulating vaccine-derived polio virus or cVDPV are outbreaks of polio that are actually caused by the polio vaccine.

Very rarely, the attenuated (weakened) virus in the oral polio vaccine can revert to a form that can cause the person who was vaccinated or their close contact to actually develop polio.

It should not be confused with VAPP or vaccine-associated paralytic polio. With VAPP, the original strain of attenuated vaccine virus reverts to a form that can cause polio, but it does spread from one person to another, so does not lead to outbreaks.

cVDPV Outbreaks

Fortunately, both VAPP and cVDPV are rare.

How rare? VAPP only occurs in about 1 in every 1.27 million children receiving their first dose of OPV.

And according to the WHO, there had only been about 24 outbreaks of cVDPV over the past 10 years. Tragically, this has resulted in at least 750 cases of paralytic polio in 21 countries.

An outbreak of cVDPV in Syria will be controlled by 355 vaccination teams that will vaccinate up to 328,000 children.
The WHO reports that an outbreak of cVDPV in Syria will be controlled by 355 vaccination teams that will vaccinate up to 328,000 children.

A new outbreak of cVDPV in Syria adds to those numbers though.

After being polio free for 15 years, since 1999, Syria began having cases of wild type polio again in 2013 (35 cases) and 2014 (1 case). Those polio cases and the emergence of an outbreak of cVDPV2 (there are three strains of polio virus – this outbreak was caused by the type-2 strain) highlight the effects of years of poor immunization rates because of war.

While there are many challenges to getting kids vaccinated in Syria, up to 355 vaccination teams with 61 supervisors will be working out of five vaccine distribution centers to vaccinate 328,000 children to control the outbreak and get kids vaccinated.

Circulating Vaccine-Derived Polio Virus

Just like wild type polio, we can stop cVDPV by increasing vaccination rates and increasing access to improved sanitation facilities.

Why?

Although anti-vaccine folks routinely cry wolf about shedding, the oral polio vaccine really does shed – in the stool of people who have been recently vaccinated. You can then be exposed to the attenuated polio vaccine virus (which can help give immunity to others in the community by passive immunization) or a strain of cVDPV (which can, unfortunately, help give others, especially if they are not vaccinated, paralytic polio) if they are exposed to open sewage or can not practice proper hygiene, etc.

Can’t we just stop using the live, oral polio vaccine?

Although a serious side effect of the vaccine, the vaccine’s benefits clearly outweigh the risk of both VAPP and cVDPV while polio is endemic (lots of cases) in a region, after all, without the vaccine, hundreds of thousands of children would get polio and would be paralyzed.

In polio-free countries, the risks of VAPP and cVDPV becomes greater than the risk of polio though, and they move to the inactivated polio vaccine. That helps prevent a situation in which the polio vaccines actually causes more cases of polio than wild type polio viruses.

Eventually, all countries will move to the IPV vaccine as we move closer to polio eradication. We came one step closer to that point in April 2016 when all countries that were still using the oral polio vaccine switched from trivalent OPV (three strains) to bivalent OPV (two strains) for their routine immunization programs. This could eliminate up to 90% of cases of cVDPV (most are caused by the type-2 strain which is not in bOPV)!

What To Know About cVDPV

Circulating vaccine-derived polio virus outbreaks are a rare side effect of the oral polio vaccine.

More Information About cVDPV

Eradicated Diseases

Once a vaccine-preventable disease is eradicated, the worldwide incidence of the disease is reduced to zero so that intervention, including immunizations, are no longer needed.

Eradicated Diseases

Only one vaccine-preventable disease has actually been declared eradicated in the world – smallpox in 1980.

Rinderpest was also eradicated with vaccines, but unlike smallpox,  rinderpest was a disease of livestock.

The second vaccine-preventable disease to be eradicated will likely be polio.

Guinea worm disease may be eradicated first, but not with the help of vaccines.

Eliminated Diseases

Many more vaccine-preventable diseases have been eliminated, especially in developed countries.

Similar to eradication, when a disease is eliminated, the incidence of disease is reduced to zero, but only in a particular geographic area. Unlike eradication, since the disease is still around in other areas, people must continue to get vaccinated so that the disease doesn’t come back in that area.

To be more clear, when an epidemiologist says that a disease is eliminated in an area, what they are really saying is that the endemic form of the disease has been eliminated – someone has to reintroduce the disease from outside the area for outbreaks to occur. So you can still have cases and even big outbreaks, like we continue to see with measles in the United States, however, they always start with someone who initially got infected from outside the country.

In the United States, endemic yellow fever, polio, measles, rubella and respiratory diphtheria have all been eliminated. So have neonatal tetanus and congenital rubella syndrome:

  • endemic yellow fever (1905), spread by mosquito bites, was the first diseases to be eliminated
  • endemic polio was declared eliminated in 1979
  • endemic measles was declared eliminated in 2000
  • neonatal tetanus was declared eliminated before 2000
  • endemic rubella and congenital rubella syndrome were declared eliminated in 2004
  • endemic respiratory diphtheria was declared eliminated in 2009 and the last big outbreak was in the 1970s

Again, even though these diseases have been eliminated in the United States, that doesn’t mean that you can’t get them anymore. If you are not vaccinated or have a problem with your immune system and travel to an area of the world where these diseases are still common, you are at risk to get sick and bring that disease home with you, infecting others.

Disease Control

Unfortunately, not all diseases can be eliminated and eradicated.

This may have nothing to do with how well a vaccine works or whether or not people get their kids vaccinated though.

In some cases, an infection might not be contagious and is simply found in the environment, like Ascariasis (roundworms) or tetanus. To eradicate tetanus, we would have to get rid of the tetanus bacteria at its source – soil!

Other reasons that a disease might not be able to be easily eliminated or eradicated could include that:

  • it can also infect animals – rabies, yellow fever, Chagas’ disease
  • the disease causes infections without symptoms – Amebiasis
  • the presence of asymptomatic carriers – diphtheria
  • natural infection doesn’t provide life-long immunity – malaria
  • the disease doesn’t always have obvious symptoms – polio
  • people are contagious before they have obvious symptoms – measles

Hopefully these challenges will soon be overcome for more diseases though, especially vaccine-preventable diseases like polio and measles.

Goals for Global Elimination and Eradication of Diseases

Tragically, we have a long history of not meeting our goals for disease elimination and eradication.

Still, a lot of progress has been made over the years, millions of lives have been saved, and many more deaths will be prevented if we meet our current goals to eradicate or eliminate these diseases:

  • polio – since the initial war on polio was started by President Franklin D Roosevelt in 1938 and the development of the first polio vaccines in the 1950s to the creation of The Global Polio Eradication Initiative in 1988, eradicating polio has been a priority for health experts. Unfortunately, we missed the first goal of eradicating polio by 2000, but are certainly getting close, as only three countries still have endemic polio – Afghanistan, Nigeria and Pakistan – and worldwide cases are at all time lows. The new goal is to have a polio-free world by 2018!
  • measles – We have missed a lot of the goals on the way to eradicating measles, including the goal to eliminate measles in the United States by 1982 (wasn’t met until 2000), the goal of global eradication of measles by 2010 which was first set in 1996, and the goal of reducing global measles mortality by 90% by 2010 over 2000 levels (there was a 74% decrease though!). We will hopefully meet the latest goals of the Global Measles and Rubella Strategic Plan 2012-2020.
  • maternal and neonatal tetanus – while many people associate tetanus with stepping on a rusty nail, tetanus can also affect mothers and their newborn babies, especially when hygienic practices aren’t available when the baby is delivered or when they care for the baby’s umbilical cord. Although the target dates have been postponed from the initial goals of 1995, 2000, 2005 and 2015, eliminating maternal and neonatal tetanus is still a goal. Considering that at least 34,000 newborns died of neonatal tetanus as late as 2015, which is down from 787,000 in 1988, significant progress continues to be made by the Maternal and Neonatal Tetanus Elimination partnership.
  • Guinea worm disease – although not usually life-threatening, Guinea worm disease is still a serious disease that causes suffering for those who become infected with the Guinea worm larvae that can grow to become adults that are 2 to 3 feet long. Fortunately, Guinea worm disease should be the next disease that is eradicated, with cases at an all time low thanks to the efforts of The Carter Center.
  • lymphatic filariasis (Elephantiasis) – transmitted by infected mosquitoes, lymphatic filariasis is another disabling condition that has been targeted for elimination using insecticidal bed nets and drugs donated by Merck and GlaxoSmithKline, hopefully by 2020.
  • taeniasis/cysticercosis (tapeworms) – eating undercooked pork that is infected with larval cysts of the tapeworm Taenia solium can cause intestinal tapeworms (taeniasis). Swallowing the eggs of these intestinal tapeworms (located in an infected persons feces) can lead to getting cysticercosis, in which the larval cysts can infect brain (neurocysticercosis) and muscle tissue, etc. Although thought to be potentially eradicable, cysticercosis is considered to be of several major neglected tropical diseases.
  • mumps – a vaccine-preventable disease that is thought to be potentially eradicable.
  • leprosy – using expanded multi-drug therapy regimens, leprosy is now in the final push phase of elimination.
  • river blindness (onchocerciasis) – a parasitic infection that is spread through the bite of small black flies, river blindness is targeted for eliminated in select regions using a drug donated by Merck.
  • trachoma – another eye infection that is spread by flies and which can lead to blindness, blinding trachoma is targeted for global elimination by 2020. In addition to health education and corrective eye surgeries, the effort has been aided by Pfizer donating an antibiotic to fight trachoma.
  • rubella – rubella is also also targeted for elimination from at least five WHO regions by 2020.

Unfortunately, even as we make progress to control, eliminate, and eradicate these diseases, some are beginning to make a comeback.

And no, it is not just because of parents choosing to intentionally not vaccinate their children. In many parts of the world, in addition to the humanitarian crisis and health challenges posed by natural disasters, children are getting sick in war zones and refugee camps and simply can’t be vaccinated.

What to Know about Eradicated Diseases

Vaccines work well and have helped control, eliminate, and in the case of smallpox, eradicate diseases.

More on Eradicated Diseases