The best preventive measure for poliomyelitis is ensuring hygiene and encouraging good sanitation practices. But, polio prevention begins with polio vaccination. Polio vaccine has been developed against all 3 subtypes of the poliovirus and is very effective in producing protective antibodies that induces immunity against the poliovirus and provides protection from paralytic polio.
Two types of vaccine are available:
► A live attenuated (weakened) oral polio vaccine (OPV) developed by Dr. Albert Sabin.
► An inactivated (killed) polio vaccine (IPV), developed by Dr. Jonas Salk.
a) Oral Polio Vaccine (OPV):
Oral polio vaccine (OPV) is administered via mouth. OPV produces antibodies to all three types of poliovirus and offers protection against paralytic polio by preventing the spread of poliovirus to the nervous system. OPV is relatively inexpensive and is employed for mass immunization programmes.
Although OPV is considered safe and effective, in extremely rare instances (1 in every 2.5 million doses of the vaccine) the live virus in the OPV causes paralysis. The global public health programme accept this low risk associated with the vaccine because without it, several thousand children would be crippled annually.
Also, in rare cases, a strain of poliovirus in OPV may mutate and circulate among a population. These are known as vaccine-derived polioviruses (VDPV).
b)Inactivated Polio Vaccine:
Inactivated polio vaccine (IPV) is given by injection and acts by producing protective antibodies in the blood. However, it induces very low levels of immunity to the poliovirus and hence, provides only individual protection and does not prevent the spread of wild polio virus.
Both vaccines have been highly effective and are being used extensively to wipe out polio worldwide.