Tag: OPV

What’s the Real Risk from the Contaminated Vaccines in India?

Most people understand that polio vaccines have helped to control and get us close to eradicating polio.

Many even know that there are two types of polio vaccine – the inactivated Salk vaccine and the live Sabin vaccine.

Some might even know that there are actually three strains of polio virus that we have traditionally gotten vaccinated against, and that one of those strains, type 2, has already been eradicated.

“In April 2016 a switch was implemented from trivalent OPV to bivalent OPV in routine immunization programmes.”

OPV Cessation

That’s why we have switched to using a bivalent OPV which only contains type 1 and 3 serotypes.

Contaminated Vaccines in India

What does all of this have to do with the news of contaminated vaccines in India?

“At least three batches of polio vaccines containing 1.5 lakh vials have been found contaminated with type 2 polio virus, putting at risk India’s “polio free” status as children born after April 2016 — when the type 2 virus was withdrawn worldwide including in India — do not have immunity to this particular virus, sources said.”

Unfortunately, some contaminated vaccines were actually administered to children in the Indian states of Maharashtra, Telengana, and Uttar Pradesh before the contamination was discovered.

Will these kids get polio?

No, as the vaccines weren’t contaminated with wild polio virus.

It seems that Bio-Med Private Limited was still producing and distributing polio vaccine with the type 2 vaccine virus, even though this type of vaccine was discontinued a few years ago.

Why?

We will  hopefully find out, as the managing director of Bio-Med Pvt Ltd has been arrested, but we don’t know yet.

We do know that there is little risk from these vaccines and they won’t put India’s “polio free” status at risk.

Why would there be any risk from kids getting an extra vaccine virus strain?

It’s because the type 2 strain of polio is the most likely to cause cVDPV, or outbreaks of polio that are actually caused by the polio vaccine.

Fortunately, these outbreaks are very rare.

A dose of IPV is the backup plan to make sure a problems with the switch to bOPV doesn't end up in a tragedy.
A dose of IPV is the backup plan to make sure any problems with the switch to bOPV doesn’t end up in a tragedy.

But kids in the area are at even less at risk from these “contaminated” vaccines because as part of the plan to switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV), they likely got a dose of IPV, which includes protection against all three polio virus strains.

Not that this means that it isn’t a problem that a company was making and distributing a vaccine that kids shouldn’t have been getting.

That is terrible!

It just isn’t as big a danger as some folks are making it out to be. It is extremely unlikely that there will be any cases of polio in India, and definitely not a resurgence of polio because of these vaccines, as some have suggested.

The real risk will be that an isolated event will scare folks away from getting vaccinated and protected, even though we know that these events are rare and that vaccines are safe.

More on Contaminated Vaccines in India

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