Influenza Immunization Procedures

To the Editor:—  I should like to take issue with statements made by Samuel Katz, MD, in his answer to a question (209:1911, 1969) regarding the intradermal method of administering influenza virus vaccine. Dr. Katz suggests that such administration is warranted only "under special situations," such as booster doses, in times of critical shortage, to immunize infants and children under 5 years of age, or older people who fall in the "high risk" category in whom an ensuing reaction to the vaccine would be undesirable.He correctly emphasizes the necessity that in administering the vaccine intradermally, it must be absolutely certain that the injection is given into and not beneath the skin in order for it to be effective immunologically. But although, as Dr. Katz points out, individuals receiving two 1-ml doses of the vaccine subcutaneously have a somewhat higher hemagglutinin titer than those getting the vaccine intradermally in two