Tag: IPV

What Happens if We Stop Using Oral Polio Vaccines?

As we occasionally hear reports of vaccine derived polio, it shouldn’t be surprising that anti-vaccine folks are calling for the end of all use of the oral polio vaccines that can trigger these cases.

Do you recognize the NVIC and ICAN? Think Barbara Loe Fisher and Del Bigtree... and ask them why they want to bring back polio.
Do you recognize the NVIC and ICAN? Think Barbara Loe Fisher and Del Bigtree… and ask them why they want to bring back polio.

Got any idea of what would happen if anyone listened to them?

What Happens if We Stop Using Oral Polio Vaccines?

Believe it or not, a plan is already in place to stop using oral polio vaccines.

So why haven’t we done it yet?

“In April 2016 a switch was implemented from trivalent OPV to bivalent OPV in routine immunization programmes. Following WPV1 and WPV3 eradication, use of all OPV in routine immunizations will be stopped.”

OPV Cessation

It is obviously because we haven’t yet eradicated wild polio!

“The GPEI’s achievements are evident not just in the retreat of WPV to geographic corners of the world, but also in the successive elimination of WPV types. In 2015, WPV type 2 was declared eradicated; WPV type 3 has not been seen since 2012; and while WPV1 has yet to be interrupted, its incidence has been reduced by over 90% since 2014.”

Polio Endgame Strategy 2019–2023

We are very close though.

“In impoverished communities with substandard sanitation and living conditions, vaccine strain poliovirus can contaminate water sources used for bathing and drinking, which can lead to more cases of vaccine strain polio paralysis,” said Barbara Fisher, co-founder and president of the National Vaccine Information Center. “Until polio eradication campaigns stop using live oral polio vaccine, the vaccine strain polio virus will continue to cripple children and adults.”

Vaccination-wary groups call for halt of oral polio vaccine

But if we stopped using oral polio virus vaccines before polio was eradicated, we would simply start seeing more cases of wild polio. And they would be at much higher levels than the vaccine derived cases we are seeing now.

“While over 18 million people who would have been paralysed by polio are walking today as a result of the eradication programme, we have not yet reached zero – and our mission to reach every last child remains as urgent as ever. If we stop our efforts now, within ten years we could see as many as 200,000 new cases each year, all over the world. Simply put, children everywhere remain at risk until polio is eradicated.”

Polio Endgame Strategy 2019–2023

Is that what Barbara Loe Fisher is proposing?

The Endgame Plan 2013-2018 succeeded in certifying South-East Asia (SEARO) as polio-free, brought the African Region closer than ever to eradication of wild poliovirus,  possibly eradicated two out of three wild poliovirus strains, set the world on the path of phased Oral Polio Vaccine (OPV) removal, stopped outbreaks in Syria and Horn of Africa, and cornered wild poliovirus circulation to a joint cross-border reservoir between Afghanistan and Pakistan.
The Endgame Plan 2013-2018 “succeeded in certifying South-East Asia (SEARO) as polio-free, brought the African Region closer than ever to eradication of wild poliovirus, possibly eradicated two out of three wild poliovirus strains, set the world on the path of phased Oral Polio Vaccine (OPV) removal, stopped outbreaks in Syria and Horn of Africa, and cornered wild poliovirus circulation to a joint cross-border reservoir between Afghanistan and Pakistan.”

What if instead of just stopping oral polio vaccinations, we went ahead and switched to IPV now, before wild virus interruption?

Would that be so bad?

Well yeah, it would, since IPV doesn’t stop the transmission of the polio virus.

IPV does prevent you from actually getting paralytic polio, but not from getting a polio infection and spreading it to others. So if we switched to IPV now, we would never actually eradicate polio.

OPV, on the other hand, prevents both paralytic polio and the spread of infection. Unfortunately, it can also rarely mutate and cause paralytic polio. And when vaccination rates are low, these mutant strains can even cause outbreaks.

Why do the outbreaks of mutant strains of polio only happen when vaccination rates are low? Because in addition to preventing infection from wild strains, the polio vaccines can prevent paralytic polio that is caused by the mutant strains!

But why use a vaccine that can mutate like that? It’s simple. The risk of wild polio is so much greater before OPV gets wild polio virus strains under control.

Don’t Spoil the Polio Endgame

There have been some hiccups, but we are very close to eradicating polio.

“In 1988, when the World Health Assembly declared its commitment to eradication and the Global Polio Eradication Initiative (GPEI) was formed in pursuit of this goal, there were 350 000 annual cases of WPV in 125 countries. By the end 2018, only 33 cases were identified – all from two neighbouring countries (Afghanistan and Pakistan).”

Polio Endgame Strategy 2019–2023

And while there are plenty of challenges ahead, including:

  • Ongoing conflicts in the last remaining polio-affected regions.
  • Weak or fragile health systems and extreme poverty in both endemic and non-endemic countries.

Let’s not add to those challenges and let anti-vaccine folks bring back polio.

“The medical establishment repeatedly claims that the science regarding vaccines is settled,” said Del Bigtree, CEO and founder of Informed Consent Action Network, adding that the outbreak of vaccine-derived cases “highlights the danger of eliminating the human and civil right of informed consent with regard to vaccines — a right available for all other medical products and procedures.”

Vaccination-wary groups call for halt of oral polio vaccine

Let’s not let them scare parents away from vaccinating and protecting their kids, which would lead to even more cases of both wild polio and vaccine derived polio.

More on the Polio Endgame

What Is the Morbidity/Mortality Rate of the Polio Vaccine vs the Wild Virus?

Some anti-vaccine folks still think that the risks of vaccines are far greater than the risks of the vaccine-preventable diseases they keep you from getting.

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. Photo by WHO

They aren’t, but you can kind of understand why they might think that with a disease like polio, when they might never actually have known anyone to have the disease.

What Is the Morbidity/Mortality Rate of the Polio Vaccine vs the Wild Virus?

Still, even though polio is under good control and close to being eradicated, the risk/benefit ratio clearly favors getting vaccinated and protected.

That’s because the polio vaccines are very safe and if we stopped vaccinating, polio could come back.

In fact, morbidity/mortality from polio vaccines are decreasing, as we are using much less oral polio vaccine (OPV) in the transition (OPV cessation) to just using inactivated polio vaccine (IPV).

“Over the past ten years, more than 10 billion doses of OPV have been given to nearly three billion children worldwide. More than 16 million cases of polio have been prevented, and the disease has been reduced by more than 99%. It is the appropriate vaccine through which to achieve global polio eradication.”

OPV Cessation

And while most developed countries already use IPV, those that are still using OPV recently switched from a trivalent (tOPV) to a bivalent (bOPV) form of OPV. We could do this because type 2 poliovirus has already been eradicated (2015)!

Of course, the issue with the OPV vaccines is that they rarely cause vaccine-associated paralytic polio (VAPP) and circulating vaccine-derived polioviruses (cVDPV).

Fortunately, this is even less common with bOPV.

As this chart from the WHO shows, polio vaccines are very safe.
As this chart from the WHO shows, polio vaccines are very safe.

So morbidity (getting sick)/mortality (dying) from polio vaccines is low.

There were only 31 cases of wild polio in 2018, in Afghanistan and Pakistan, and an additional 102 cases of cVDPV in 7 countries.

What about morbidity/mortality from polio?

“As recently as 30 years ago, wild poliovirus paralysed more than 350 000 children in more than 125 countries every year. In 2018 there were fewer than 30 reported cases in just two countries – Afghanistan and Pakistan.”

“Zero polio transmission and health for all”, WHO Director-General gives new year’s wish to the people of Afghanistan and Pakistan

With a 99.9% drop in polio cases since 1998, your risk of getting polio in most parts of the world is very low, but you still have to consider both the morbidity/mortality of polio in the pre-vaccine era and the risk of polio returning if we stop vaccinating before it is eradicated.

What about the idea that you don’t have to worry about polio because only 1% of kids with polio developed paralysis?

“The mortality rate for acute paralytic polio ranges from 5–15%.”

Disease factsheet about poliomyelitis

Well, when everyone gets polio, even 1% is a lot.

With such a safe vaccine, why put your kids at risk of getting polio?

Do you even understand what the risks are?

No, it isn’t just the risk of wild polio in Afghanistan and Pakistan.

Since the oral polio vaccines shed, if you are unvaccinated, in addition to the risk of wild polio, there is a small risk of getting circulating vaccine-derived polioviruses (cVDPV) if you are not vaccinated and protected. No, it is not a big risk, as there were only 102 cases of cVDPV in 7 countries in 2018, but it isn’t zero either.

And the other big risk is that if enough folks stop getting vaccinated, taking their chances hiding in the herd, polio will come back and our chance to eradicate another vaccine-preventable disease will fail.

More on the Morbidity and Mortality Rates of Polio

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