[The duration of humoral postvaccinal and postinfection immunity to the Venezuelan equine encephalomyelitis virus].

Serological studies on the levels of virus-neutralizing antibodies (VNA) against Venezuelan equine encephalomyelitis virus (VEE) were carried out by the standard method in 280 human subjects given a single primary inoculation of experimental forms of live vaccines against VEE prepared from attenuated strains No. 15 and No. 230. The VNA were found to persist in the blood of the vaccinees for 5-25 years (the observation period) from the time of vaccination practically at the same level. The VNA titres did not depend on the form of the preparation (for subcutaneous or oral administration) used for immunization. Similar studies were carried out on sera from 17 convalescents after VEE experienced in the past. An identical result was obtained. It is suggested that immunity to VEE persists for life.