[An attenuated strain of vaccinia virus (MVA). Successful intramuscular immunization against vaccinia and variola (author's transl)].

The attenuated MVA strain of vaccinia virus was previously shown to be innocuous and immunogenic at intracutaneous injection. It was therefore suggested for clinical trial. Preliminary results in human vaccinees are promising. The present experiments were initiated to study the intramuscular injection of the vaccine as a preferable route of administration. Histological examination was done in rabbits and monkeys. At the site of injection there were but minor inflammatory reactions considerably less pronounced than after the injection of commercial tetanus vaccine which was used for comparison. Intramuscular immunization with strain MVA repeated twice protected rabbits against an intravenous challenge with vaccinia strain Elstree; monkeys were protected against experimental smallpox. Intramuscular immunization with attenuated smallpox vaccine is suggested for clinical trial.