Washington, DC, December 29, 2016 (PAHO/WHO)-In 2016, 155 countries and territories from the Americas and around the world took a historic step towards the eradication of poliomyelitis. During two weeks in April, in a process coordinated by the World Health Organization (WHO), known as "the switch," the health sector changed one type of polio vaccine for another.

In the Americas, "the switch" was led by the Pan American Health Organization (PAHO) and consisted of removing the trivalent oral polio vaccine (tOPV), which protected against all three types of polio virus, and replacing it with a new bivalent (bOPV) vaccine, which protects against two of them (type 1 and type 3), since type 2 poliovirus has been eradicated.

This process will strengthen the immunity of persons vaccinated against remaining polioviruses and reduce the risk of vaccine related polio cases.

"The switch was a milestone in global public health," said Cristina Pedreira, PAHO/WHO Regional Immunization Adviser. "There is no similar experience in which 155 countries united, and in a coordinated and synchronized manner, replaced one vaccine with another."

In PAHO countries and territories, staff visited all vaccine warehouses and vaccination service points to ensure that no trivalent vaccine was left behind, thus preventing its use by mistake. They submitted reports that were signed by the country and revised by their national certification committees, and then at the regional level, by the Regional Certification Commission.

"The primary heroes of this effort are the countries, the immunization programs in the countries, and the thousands of health workers, that every day go out to look for children who are not vaccinated to protect them from polio," said the Chief of the Expanded Program on Immunization of PAHO/WHO, Cuauhtémoc Ruiz Matus.

To achieve global polio eradication, countries must commit to complying with the requirements of the Polio Eradication and Endgame Strategic Plan, developed by WHO and partners in the Global Polio Eradication Initiative, which aims to rid the world of polio.

The Endgame, as the plan is known, includes the safe containment of all poliovirus stocks: wild, vaccine-derived, and Sabin type 2 to minimize the risk of reintroduction of these viruses into the population. These materials can only be stored in facilities that perform essential functions of vaccine production and research, and that comply with all the necessary guarantees outlined in the Global Containment Action Plan (GAPIII) to be a poliovirus-essential facility.

"If we want to ensure a polio-free world, we have to ensure that poliovirus containment is really achievable," said Gloria Rey, PAHO/WHO Regional Advisor for the Laboratory Network.

This year, the American continent celebrated 25 years without cases of wild poliovirus. Globally, the world is very close to achieving the goal of polio eradication. Today, there are fewer cases in the world than at any time in history.

Regional efforts will now focus on ensuring that more than 95% of children less than 1 year of age are vaccinated against polio in each municipality of the countries of the Americas, as well as strengthening surveillance for cases of acute flaccid paralysis and to comply with the requirements of the Endgame.


-Video: The switch in the Americas 
-The Americas celebrate 25 years without polio