<prompt> The characteristics of polio vaccine are all except -Maintenance of cold chain100 immunisationKilled vaccine is effective in India5 doses of OPV given  <response>: Park;s Textbook of Preventive and Social Medicine 23rd edition Page no: 206, 207 After 3 doses of OPV, the mean propoion of infants with detectable serum neutralizing antibody level was only 73 for type1, 90 for type 2 and 70 for type 3 polio virus 