Stability of the Hungarian National BCG Reference Preparations. Trend of viability during 4-7 years storage at +4 degrees C.

The stability of the viability of the Hungarian BCG Reference Preparations (Vaccine Bch. Nos: 265, 456, 505) was tested according to the recommendation of the World Health Organization. The BCG viable units of the vaccines were estimated from the colony counts determined on solid medium. The control data of the BCG viable units expressing the stability in 10(6)/ml values were analysed up to 7 years in a three-step statistical model applying unbiased parameter estimates, valid hypothesis test and multiple comparison. The presented model verifying the stability of the reference preparations ensures the reliability of the assays to accept or reject the viability at controlling routine BCG vaccines in comparison with the reference preparations.