Until 31 December 1992, Member States in which all collection centres contain only animals which have not been vaccinated against Aujeszky's disease giving a negative reaction to the serum neutralization test, or to the ELISA test for Aujeszky's disease, in accordance with the provisions of this Directive: ... - may not prohibit the admission of semen from boars which have been vaccinated in the collection centre with the G1 deleted vaccine, provided that: - such vaccination has only been carried out on boars that were serum-negative with regard to the virus of Aujeszky's disease, - serological examinations carried out at the earliest three weeks after vaccination of such boars do not reveal the presence of antibodies induced by the disease virus.
