Tag: elimination

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

Fake News About Measles Outbreaks?

Many news organizations ran with a story about a multi-state measles outbreak recently.

The CDC tweeted a correction about the multi-state measles outbreak story.
The CDC tweeted a correction about the multi-state measles outbreak story.

They got something wrong though.

There is no ongoing, single, multi-state outbreak of measles this year.

Fake News About Measles Outbreaks?

Is it understandable that some media outlets would have been confused by recent CDC reports?

Not really.

The CDC Measles Cases and Outbreaks page hadn’t been updated since late-July and is still reporting case numbers that are “current as of July 14, 2018,” so there really was no recent CDC report to generate all of this extra attention.

“From January 1 to July 14, 2018, 107 people from 21 states (Arkansas, California, Connecticut, Florida, Illinois, Indiana, Kansas, Louisiana, Maryland, Michigan, Missouri, Nevada, New Jersey, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Tennessee, Texas, and Washington) and the District of Colombia were reported to have measles.”

CDC on Measles Cases and Outbreaks

Although it has been changed to say “107 individual cases of measles have been confirmed in 21 states,” there was nothing to indicate it was a single outbreak that the CDC was monitoring as many sites reported:

Few sites were immune to using a click-bait title to scare folks about the "outbreak."
Few sites were immune to using a click-bait title to scare folks about the “outbreak.”

Unfortunately, many of these reports are still online.

How did it happen?

It’s likely because you have reports from organizations and websites that seem to want to push out content, but don’t have much of a budget to pay health or medical writers to make sure it is accurate.

2018 Measles Cases and Outbreaks

It’s also unfortunate that some of these sites, in trying to correct the idea of a single, nation-wide outbreak, are now trying to minimize this year’s measles outbreaks.

No, there isn’t one large outbreak that is spreading across the United States, but there are a lot of smaller outbreaks, some of which are still ongoing.

And these outbreaks are not something that should still be expected, as we have had a safe and effective measles vaccine for over 50 years and measles was declared eliminated in the United States in 2000!

There is also something very much different about 2018, that not surprisingly, no one is reporting about.

With over 107 cases, things seem very similar to last year right, when we had about 118 cases?

The thing is, in 2017, there was one large outbreak, in Minnesota, with 79 people.

In 2015, at least 139 of 189 cases were from just three large outbreaks, in California (Disneyland), Illinois, and South Dakota.

See what’s different?

This year seems to have more individual cases in more states, each with the potential to grow into one of those big outbreaks.

Why?

You can blame the rise in measles outbreaks in Europe and other parts of the world. And some folks not getting vaccinated and protected and exposing the rest of us when they get sick.

Putting us at risk even though measles is a life-threatening infection, a safe and effective vaccine has been available for 50 years, and every anti-vaccine myth that scares folks has been refuted a thousand times.

That’s the story.

Who’s telling it?

More on Reporting on Measles Outbreaks

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