While working in Government service, I took part in the 'Indian Pulse Polio Campaign' [as part of my duty] and had supervised immunisation of thousands of children given Oral Polio vaccine[OPV]. On a single day all the kids below 5 years were given the vaccine. This Campaign continued twice a year for several years. Still it is continuing in India at least in some states. What is the result? India [along with 3 other countries ] still reports many Polio cases. Why the Polio eradication campaign with OPV failed?
Pushpa Bhargava in an interesting article in 'The Hindu' is of the opinion that it was destined to fail. Many of the experts as early as in 1988 were favouring Injectable inactivated Polio Vaccine[IPV] for achieving eradication.
Many investigations show that while in developed countries three doses of IPV or OPV can produce a protection rate of 98 percent, in developing countries it was consistently found that OPV is much less effective than IPV. Two doses of IPV can generate a protection rate of 89 percent, while the protection rate of two doses of OPV is only 72 percent. Three doses of IPV can protect almost 100 percent of the children, while three doses of OPV protect less than 85 percent of the children The reasons for the difference in OPV efficacy in developed and developing countries are not clear. Problems with the cold chain explain only a small part of the difference. The major reason might be the interference of other virus infection, e.g., diarrhea caused by viruses, which hinders the uptake of OPV.
Then why the Government went along with WHO in choosing OPV for eradication?