Polio vaccination has already saved over 16 million people from paralysis and left us verge of global polio eradication. But the vaccines we have still aren’t perfect, and might not be the best tools to protect us post-eradication. So our researchers are looking towards developing novel, ‘safer’ vaccines to guarantee that polio soon becomes a disease of the past. 
 

We currently have two tools to control polio, the Oral Polio Vaccine (OPV) and the Inactivated Polio Vaccine. Both vaccines work by introducing non-infectious forms of polio virus into the body, which then encourages our immune system to produce special proteins, known as antibodies, that help fight off the invading virus.

The adoption of these vaccines has already saved over 16 million people from paralysis, and today polio is found only in Afghanistan, Pakistan and Nigeria. Our current vaccines have been effective in taking us towards eradication but they might not be the best means to protect us post-eradication. With both vaccines there’s a small risk of re-introducing polio into the environment, which isn’t ideal in a world where poliovirus has already been wiped out. New, safer vaccines are needed for the end game.

New approaches

Our researchers are investigating three different approaches for new vaccines that will allow us to continue to fight polio after eradication. 

1. Stable oral polio vaccines 

OPV is the preferred option for controlling polio outbreaks worldwide. It’s easy to administer and offers extended protection within communities, by building immunity not only in the person who receives it, but also those around them. This makes it ideal for use in outbreak situations.

However, it can be a double-edged sword for polio. Over 30 years ago our scientists identified the dark secret of this vaccine, showing that within weeks of vaccination the weakened virus could accumulate genetic changes turning into an infectious vaccine-derived poliovirus (VDPV) capable of causing disease.

In situations where a population is seriously under-immunized, there is a risk of these vaccine-derived polioviruses circulating in the community. After eradication, these vaccine-derived viruses could also lead to the re-emergence of polio.
 
Our scientists have developed safer, genetically stable virus strains that can be used for the OPV but won’t revert back to their infectious form.
Vaccine-dervived polio viruses result from genetic changes or mutations to the ’weakened’ poliovirus found in the oral polio vaccine. 

 
 

2. Safer innactivated polio vaccines 

Innactivated polio vaccine (IPV) production uses huge vats of live poliovirus. Although IPV manufacture is carefully controlled, there’s always the threat of accidental re-introduction of the virus into the environment. This could be particularly dangerous in a post-eradication world. 

Research at NIBSC has identified new strains of poliovirus that are suitable for vaccine manufacture but are essentially non-infectious. As these strains can still provide protection against polio, they leave us with a safer alternative for future IPVs. 


3. Making vaccines without the virus

Accidental release of the live virus during polio vaccine production could reverse decades of work towards eradication.
 
Virus-like particles (VLPs) are empty protein shells that look the same as the virus but lack the genetic material needed for the virus to multiply and cause disease. They could make ideal vaccine candidates, but at the moment they’re not stable enough to use in vaccine production.  
 
To solve this problem our researchers have developed a method to produce stable VLPs.They’re now looking to transfer this approach to systems such as plants, insect and human cells so the large amounts of VLPs needed for vaccines can be made. 

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