THE IMMEDIATE mortality of encephalomyelitis following Jennerian vaccination is usually stated to be in the region of 30 to 50%. The mortality has, however, tended to be lower in recent series. Greenberg and Appelbaum,1 for example, report 46 neurologic illnesses following approximately 5,000,000 vaccinations in New York City in 1947, with 8 deaths, 4 of which were due to coincidental disease, such as tuberculous meningitis or coronary thrombosis. The remaining four deaths were probably encephalitic, though the classic histopathological changes were lacking.
As regards the remote prognosis, it is commonly stated that recovery from postvaccinal encephalomyelitis is usually remarkably complete and that residual symptoms are exceptional,2 though, in fact, accounts of the subsequent fate of patients recovering from the acute illness are scanty. Most of the standard textbooks indicate a low incidence of sequelae—"complete recovery is the rule"3; "recovery is usually complete"4; "in patients who recover