The Public Health Ministry will eradicate a total of 1.2 million doses of trivalent oral polio vaccines (OPVs) today, said Amnuay Kajeena, director of the Department of Disease Control.
A worker wearing protective gear puts medical waste into designated bins for disposal at a medical waste incinerator in Bangkok’s Prawet district. PHOTOS BY Somchai Poomlard
The trivalent OPVs will be replaced with bivalent OPVs, he added.
Dr Amnuay said the country will switch from using trivalent OPVs to bivalent OPVs, to remove the type 2 components from immunisation programmes, starting tomorrow.
Trivalent OPVs have been used to weaken type 1, 2 and 3 poliovirus strains while bivalent OPVs target types 1 and 3.
Dr Amnuay said the change came in response to World Health Organisation (WHO) requirements under the Polio Eradication and Endgame Strategic Plan 2013-2018.
In September 2015, The WHO declared that poliovirus type 2 had been eradicated from the planet as no cases had been detected since November 1999.
However, there are cases of poliomyelitis caused by the type 2 vaccine, due to a mutated form of the virus that comes from the vaccine itself in some countries.
The WHO decided to remove the type 2 strain from OPVs and switch from trivalent OPVs to bivalent OPVs in April 2016.
Earlier, the Food and Drug Administration recalled trivalent OPVs from distributors and hospitals, according to Dr Amnuay.
Samples of the trivalent oral polio vaccine are shown prior to disposal at a medical waste incinerator.