Solutions put forward: India has gained remarkable success in controlling poliomyelitis through pulse polio immunization. Recent surveillance reports indicate that most of the wild virus is in circulation in Northern India (esp. UP, Bihar) causing paralytic polio. Kerala is polio free from some time so epidemiology has changed but the policy & strategy to eradicate polio are still the same across the country. So few strategies have been put forward in order to tackle this situation. It is proposed that, in the areas where polio virus (wild) is not circulating.IPV (Injectable Polio Vaccine) should be commenced in order to reduce VAPP and areas with high incidence of polio should continue to use oral polio vaccine.

Inactivated Polio Vaccine (IPV): IPV is derived from three wild strains of poliovirus, types 1, 2, and 3, which are inactivated by formalin. IPV is highly immunogenic with > 90% of vaccine recipients developing protecting antibodies following 2 doses of vaccine and > 99% after 3 doses. These antibodies persist for several years after primary immunization with IPV. Study in Tamil Nadu (India) comparing efficacy of OPV & IPV has shown higher efficacy with latter (66% Vs 92%). There were initial concerns that IPV induces lower level of mucosal immunity than OPV & it doesn't get excreted in the stools of vaccines so it may be less efficacious in preventing wild virus circulation. But now studies have shown that enhanced IPV (eIPV) induces adequate amount of IgA formation in nasopharyngeal and intestinal secretions almost equivalent to that induced by oral polio vaccine.

Schedule of IPV: Many schedules have been tested e.g. eIPV only, sequential eIPV - OPV in combination with DPT and as part of a number of investigational combination including acellular pertussis, Hib vaccine, Hepatitis B vaccine etc. Combined schedule of OPV & IPV may be useful to accelerate the eradication of polio in developing countries. Combined schedule with simultaneous delivery of OPV & IPV at 6,10 & 14 weeks had an excellent serologic response in 3 different parts of world with mucosal immunity equivalent to that provided by OPV alone without the risk of VAPP. Sequential IPV/OPV vaccination trials confirmed its efficacy in polio eradication and safer than OPV by reducing VAPP among recipients. Denmark, Israel have become polio free only after introducing OPV-IPV combination. In one study it was suggested that in countries where wild type virus no longer circulates and where general hygiene is good eIPV alone might be the vaccine of choice.

Side effects of IPV: No serious side effects are reported. Rarely anaphylaxis may occur within few minutes to few hours after vaccination.

Advantages of IPV: It is safe in immunodeficient hosts, patient on steroids & radiation therapy, in elderly and even in pregnancy. It does not require stringent conditions during storage & transport and has a longer shelf life.

Disadvantages of IPV: There are few limitations of IPV as well. Virus content is 10,000 times more than OPV hence it is costlier. It requires trained personnel to administer. There is no excretion of virus, hence contacts are not benefited. It is not useful in controlling epidemics.

Contra Indications of polio vaccine: IPV is only contraindicated in children who have experienced a severe allergic reaction to a previous dose of IPV or to streptomycin, polymyxin B, or neomycin. OPV is contraindicated in children who have immunosuppressive conditions due to congenital immunodeficiency (agammaglobulinemia or hypogammaglobulinemia), cancer (leukemia or lymphoma), immunosuppressive chemotherapy, or acquired immunodeficiency syndrome (AIDS). OPV also is contraindicated for family and other close contacts of immunocompromised people because of the risk of spread of OPV to the affected person.