Injectable vaccine is much more effective than oral vaccine and eliminates the risk of vaccine-polio. There is also a looming threat of virus importation from Pakistan. These were the inferences drawn during deliberations on the sidelines of Ranbaxy Science Foundation’s 32nd Round Table Conference on “Lessons from the Success of Polio Elimination”.

The deliberations highlighted the importance of switching from the oral polio vaccine (OPV) to the injectable polio vaccine (IPV) in India beginning next year.

Experts also warned that any delay in introducing it can have detrimental effect on public health. Said Dr T Jacob John, chairman, Child Health Foundation, “Though we have successfully combated the menace of polio using oral vaccines containing live viruses, it has to be kept in mind that only the wild polio viruses have been eliminated from India, while the vaccine-derived polioviruses still remain a threat. IPV, planned to be introduced in 2015, is inevitable if we have to prevent vaccine-derived cases of polio and achieve total eradication of the disease. Once IPV is launched to preempt circulating vaccine-derived poliovirus, we can gradually discontinue OPV, starting with type 2 component.”

According to health experts, IPV, though more expensive, carries inactive forms of all three strains (Type 1, 2 and 3) of the polio virus, with no risk of virulence. In contrast, OPV carries live but weakened form of the virus which can give rise to occasional cases of polio, especially of the Type 2 strain, the wild counterpart of which is now absent.

“IPV is much more effective than OPV in a country like India when introduced in the routine immunization program.Had we adopted IPV earlier, we could have banished polio years ago from our shores due to it having much higher efficacy than OPV. As India moves to IPV next year, it would be critical to achieve and retain high levels of routine immunisation in all states,”

Prof NK Ganguly, former director general, Indian Council of Medical Research said, “For a successful rollout of IPV in the country, the Government needs to build capacity and ensure sufficient stocks and logistics. The availability of the vaccine would be a critical factor. We also need to build advocacy among the people and have trained manpower ready from the primary immunisation field to administer the injections.”

The success of India’s polio campaign is particularly striking since many other disease control projects have been an abject failure. For example, TB control started in 1962, yet India even today has the world’s largest burdens of TB and MDR TB.

Policies on polio immunisation, polio control and polio elimination ignored results from Indian research for too long and science continued to be neglected during program design. The importance of science was only appreciated in 2005, followed by a flurry of science reviews and new research in tackling the problem. It was only after science offered solutions that polio could be successfully eliminated in the country. This offers important lessons for controlling other diseases like TB in India.

According to experts, the polio program was a success because it gave equal importance to three crucial areas of sociology, epidemiology and vaccinology. Many challenges still remain, however. India needs to sustain its wild polio-free status, prevent the importation of the virus, begin phase two (“end game”) of the war on polio, and withdraw Type 2 from the trivalent oral polio vaccine because it causes polio at an unacceptable frequency.

Health experts also warned against the threat of the wild polio virus infiltrating into India from Pakistan and restarting the epidemic that was eliminated recently after a nationwide struggle spanning decades.

Prof. Ganguly said, “The threat of virus importation from Pakistan is very real. Though it is now mandatory for everyone from the neighboring country to take an additional dose of polio vaccine before entering India, measures like this can only reduce the risk, not eliminate it. The number of polio cases in Pakistan have already crossed 200 this year, the highest in more than a decade, setting alarm bells ringing. It is necessary for India to keep 100 per cent immunity status against polio until Pakistan gets polio-free. Till that happens, we have to act as if we continue to have polio in our country.”

The conference was of high quality with the deliberations by Health experts such as Dr. Sunil Bahl from WHO, Dr. Jagadish Deshpande from Enterovirus Research Centre, Dr. Arindam Nandi from Public Health Foundation of India, Dr. Roma Soloman from the Core Group Polio Project, Dr. Shobha Broor from AIIMS, Dr. Anis Siddique from UNICEF, Mr. Deepak Kapur from Rotary International, and also participants from Ranbaxy.

The Ranbaxy Research Foundation was set up in 1985 to give an impetus to R&D activities in India.