Background

Ending Polio: the final steps to success

There are 3 types of wild poliovirus (WPV): WPV1, WPV2, and WPV3. All 3 types can cause paralysis, but WPV2 was eliminated worldwide in 1999.

We have two vaccines against polio, the Oral Polio Vaccine (OPV, in drops) and the injectable Inactivated Polio Vaccine (IPV). OPV works best to prevent transmission of polio. IPV works best to boost immunity and protect against future threats once OPV is no longer needed.

Thirty years ago 350,000 children were paralyzed by polio every year. Thanks to polio vaccine, that number was reduced to 416 in 2013!

We are very close to a world without polio... but, there are important steps to take before we reach the finish line!

The last few steps:

Now - Most countries use trivalent OPV (tOPV) which protects against all 3 types of poliovirus even though type 2 has been eliminated. Very rarely OPV can cause paralysis in areas with low vaccination. This is more common with the drops that protect against type 2.

Soon- In order to eradicate polio, the world needs to eventually stop using OPV. To give added protection as we prepare to withdraw OPV, IPV will be included in routine vaccination programmes. The introduction of IPV also gives us an opportunity to remind parents about the importance of immunization and inform them that their children are due for vaccines.

Then - Once IPV is introduced in all countries, OPV that just protects against type 1 and type 3 polio (bOPV) will replace the current OPV that protects against all 3 types of poliovirus (tOPV). This change will avoid cases of paralysis caused by the type 2 part of tOPV.

In a few years - It will take 3 years after the world’s last polio case to be certain that polio no longer exists anywhere in the world. With no more polio, we can start removing even bOPV from the childhood vaccination schedule. IPV will continue to be given to ensure a polio free world.