Journal of the American Medical Association (JAMA)
is necessary that the way in which the body reacts to the combined effects of the injections and the infection be tested from time to time. This is now done by deter¬ mination of the opsonic index, a procedure that requires special facilities, some skill and much time. There is good reason to believe that persistent, ill-timed injec¬ tions of vaccine, without giving the patient time to re¬ cover from the primary depression of the antibacterial powers that follow after each injection, may do
... jection, may do great harm, and it is in order to avoid this, as well as to obtain direct evidence that the vaccine actually does stimulate the apparatus of immunization, that it is essential at least in the present stage of our knowledge to estimate the opsonic index. The only infection in which an exception to this might be made would seem to be chronic local tubercu¬ losis, provided the doses of tuberculin are small (1/1000 mg. by weight of bacillary substance) and the intervals between the injections 10 to 12 days. Clinical ex¬ perience with tuberculin in the hands of careful, critical observers like Trudeau before the days of opsonins indi¬ cates that this would be a safe course.