The virus (obtained in commerce) is not a pure product of the specific organism of variola, but in addition contains pathologic products of the inflammatory process of the calf's skin. It is obtained in the following manner: A number of incisions on the shaven skin of the calf's belly are infected with the vaccine. After a week, the pustules, which have formed in these places, are thoroughly curetted with a sharp spoon. The mass thus obtained constitutes the raw material; then the calf is slaughtered and only when at autopsy no general disease is found is this raw material used. Four times its bulk of SO per cent. glycerin is added to the raw mass, then it is kept in a cool room for a month. The mixture is then rubbed into fine particles and again allowed to stand from one to three months, when it is inclosed in the well-known lymph capillaries. During this time the glycerin destroys other bacteria (staphylococci) while the vaccine organisms remain intact.
The vaccine may be introduced in any part of the external skin, although the most favorable location is on the external surface of the upper arm, a method, as mentioned above, early practiced by the Brahmans.
In order to avoid a vaccination scar on the arm in girls, they may be vaccinated ten centimetres below the nipple (Flacks, Schlossnian), or on the legs. The latter method is to be advised only in small children who are not able to walk, older children (revaccination) often scratch or soil the vaccination areas.
The technique of wounding the epidermis is also of minor importance. It is advisable to make the vaccine wound not longer than 1 cm. and never draw blood.
Plunging needles into the skin, a method at one time much employed, does not give good results. I would advise the inexperienced to make a number of small superficial crossed incisions with a lancet. The experienced operator will accomplish more by making a fine incision with a lancet covered with the virus. Very beautiful round pustules result from boring with a chisel-like lancet, in the same manner as is clone in the cutaneous tuberculin reaction method. Surgical cleansing of the skin is not necessary. :Most physicians insist that children brought for vaccination be well washed. I merely cleanse the area of vaccination with a little ether.
After vaccination I let the children sit with the arm exposed for ten minutes, and therm allow them to dress. I tell the parents to care fully wash the arm at bedtime, in order to prevent the spreading of the virus to other parts of the body where it might produce vaccinia. I do
not think it necessary to apply a bandage to the vaccinated area. A tightly fitting bandage is even harmful to the subsequent development of the pustule, causing maceration and hindering the normal process of desiccation. The method of Paul, however, seems to be quite rational. A small amount of Tegmin is applied to the wound and sealed with a small round piece of pressed cotton.
The scars of cutaneous vaccination and the danger of external transmission of the virus would be avoided by subcutaneous injection. This method has been studied by many authorities and quite recently worked out by Knoepfelmacher and Nobl. They inject 1 c.c. of virus, diluted with 200 parts of normal salt solution, having first determined by means of bouillon culture that the virus is free from pathogenic bac teria. While its results seem to be satisfactory it has not yet to my knowledge been generally adopted. The advantage of vaccinating under the influence of red light and the subsequent protection of the pustule from exposure to all kinds of light except red rays is without scientific basis, as the course of the process is not modified.
When shall children be vaccinated? For the first vaccination, the period between the third and twelfth month of life is the most advisable. If possible it should be done at a time when the children enjoy perfect health, as the fever accompanying vaccination tends to weaken the child. Children with marked eczema should not be vaccinated, because of the danger of infecting the eczema. There are, however, no absolute contra indications; if there is danger of smallpox, vaccination is indicated regardless of anything. In cases of children with eczema, care should be taken that the wound is washed a few hours after vaccination, and that scratching is preventel at the time of the development of the pustule.
As for the season of the year when the child should be vaccinated, it is a matter of indifference.
Ilow many scarijications shall be made? The German law on vacci nation orders four incisions. The duration and degree of immunity do not seem to depend on the number of foci of infection, any more than does t he intensity of the fever. However, inoculating more than one place gives greater assurance of cessful vaccination,especially if the physician is enced.
The clinical picture of vaccination in a healthy child is fairly uniform. Deviations in some cases may be but slight.