The dream for a world free from polio appears to be taking longer than expected. The WHO in 1988, committed to eradicate polio from the world by 2000. However, in the process of eradicating wild polio, the world has caught up by the threats of attenuated vaccines used in its prevention, a new strain of the virus — circulating vaccine-derived polio-virus (cVDPV) affected 460 individuals globally in the year 2020 alone. Cases in poor-countries like Afghanistan and Pakistan is increasing and includes the Philippines, Malaysia, Yemen and 19 African countries. The attenuated vaccine for Wild polio comes from the virus grown in cell cultures which eventually lose the ability to infect humans. And these harmless viruses in a vaccine saved millions from being paralysed by Wild polio.
But, the growing no of cases of cVDPV has been the topic of increasing concern in the past few years. Interestingly, most of the cVDPV emerges as a result of mutations in a strain of poliovirus called type 2, spreading in the southern part of the earth.
For the past decade, researchers worked on the new vaccine which relies on the same principle as the old polio vaccine — the use of Infectious virus. But this time the virus has been 'triple-locked’ using genetic engineering which makes it less likely to regain its virulence. The earlier attenuated virus used in the vaccine of wild polio was 'single-locked' meaning it could regain its virulence by a single 'gatekeeper mutation'. Besides, the new vaccine against cVDPV has gone through all the safety measures and efficacy tests. Looking at the increasing number of cVDPV cases and the loss it could wreck on the long run program of a polio-free world, the WHO may approve the use of vaccine under the emergency-use listing.
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