Early and late immunity results with scarlatinal streptococcus toxin.

Conclusion

1. A complete antitoxic immunity to scarlet fever was produced by 4 doses of scarlet fever toxin (250, 1000, 2000 and 3000 skin test doses) in 70 per cent of injected persons, and a partial immunity in 26 per cent. A second series of toxin injections successfully immunized most of the refractory cases.

2. Subsequent exposure to scarlet fever showed that the induced active immunity protected the children from infection.

3. From 10 to 20 per cent of individuals who gave a negative Dick reaction after toxin injections showed a slightly positive reaction at later re-tests.

4. Groups of children who were re-tested from 9 to 14 months after the toxin injections show by a negative Dick retest that the immunity can last for at least that period of time.