Armstrong – Table of Contents

years; however cases below one year or over 8 years seemed to be rare. Encephalitis
appeared more commonly among girls, and seemed to occur most frequently with
primary vaccination. The type and source of virus seemed to have no relationship to the
occurrence of encephalitis.
The cause of the complication was unknown but most authors at that time
suggested the activation of a latent agent in the vaccine or the recipient as a possible
factor in the production of encephalitis. Others postulated that the complication was due
to the vaccine itself or to the induction of a local “hyperallergic state” in the central
nervous system by the vaccine.
Prevention of encephalitis, as advocated by the health authorities at the time, was
basically the avoidance of routine vaccination in the absence in the community of
smallpox, poliomyelitis or other transmittable infections of the central nervous system.
Practically all the authorities outside the United States, at the time, stressed the
importance of performing primary vaccinations during the first year of life, since at this
period postvaccinal encephalitis appeared to be relatively less common.
Armstrong indicated that the usual ages for performing primary vaccinations in
the United States were in the sixth or seventh year. He remarked that this would seem to
predispose the United States population to the postvaccinal complication. He also stated
that such cases had been reported from various areas of the country. He concluded his
report (19) as follows: “It seems therefore that this complication is occasionally found in
the United States, and, as health officers, we should all be on the lookout for the
occurrence of symptoms pointing to the central nervous system in persons recently
vaccinated. Should such cases come to your attention, they should be considered worthy