A note on single- and two-dose immunogenicity tests of inactive virus vaccine in chicks

Single dose extinction limit test ot inactive polio vaccine in chicks lasts 4 days and offers the same results as the two-dose test which requires 14 days. When "long-term" incubation instead of "conventional" 2 hours-incubation of the serum/virus mixtures in the neutralization reaction was used, extinction limit values higher by 0.6-0.7 log10 were regularly obtained.