Tuesday, April 05, 2016
A new oral vaccine is to be launched in the pursuit of global eradication of poliomyelitis! One hundred and fifty-six countries are all set to switch from the trivalent oral polio vaccine to bivalent oral polio vaccine. The Health Ministry in India has planned to launch the bivalent oral polio vaccine (bOPV) on April 25, 2016.
The incidence of paralytic polio has hitherto been successfully controlled by trivalent oral polio vaccine (tOPV). However, the emergence of the vaccination-related adverse effects such as vaccine-associated paralytic poliomyelitis has precluded the usefulness of tOPV. Dr Rajeev Joshi, a paediatrician, said, "Among 686 cases of paralytic polio caused by circulating vaccine-derived polioviruses (cVDPVs) that have been detected since 2006, type 2 cVDPVs (cVDPV2s) accounted for 97% of the cases."
VDPVs arise from a mutation in the human gut. They are neurovirulent, transmissible, and capable of causing outbreaks. However, poliomyelitis is on the edge of eradication in India, since the last case of wild poliovirus disease was reported in January 2011. Consequently, it is important to discontinue the use of OPV once polio eradication has been established.
Dr Jayant Joshi, a paediatrician and president of Pune branch of the Indian Academy of Paediatrics, explained, "With the switching over to bOPV and simultaneous introduction of single dose of injectable polio vaccine, we are aiming at complete eradication of poliomyelitis. Thereafter, oral polio vaccine would be completely withdrawn and replaced by injectable polio vaccine, as being currently practised in the developed countries."
bOPV has hitherto been used as a supplementary immunisation activity in the country's high-risk areas. However, the usage of bOPV will take off only from the `switch date' onwards. Moreover, complete disposal of tOPV is expected within two weeks of the switch. The government has issued national guidelines for discarding tOPV.
Dr Sanjay Lalwani, head of the paediatrics department at Bharati hospital, said, "Eventually, we want to get rid of the polio virus, be it wild virus or vaccine virus. So the bivalent oral polio vaccine will be replaced by injectable polio vaccine by 2020 which will eliminate all types of circulating polioviruses and the adverse events caused by the current oral polio vaccine."
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