Rapid antibody response to influenza vaccination in "at risk" groups

Persons attending for routine influenza vaccination in an urban practice ea ch provided three specimens of blood for evaluating their immunological res ponse. 138 (67%) of the 206 persons were defined as "at risk" by reason of morbidity as given in the guidelines published by the Chief Medical Officer . The mean age was 67 yr and 65% were aged 65 yr or more. By day 7, 71% of 31 persons had protective H1N1 titres, 61% H3N2 and 42% B. These proportion s were similar to those found at day 14 and at day 21 based on 159 persons. These findings suggest that an effective immune response is mounted within seven days of vaccination indicating that the vaccination of persons "at ri sk" is worthwhile even after an epidemic has established itself. This is no t a reason to modify present policy of routine vaccination in early winter well before epidemics are likely to occur. (C) 2000 Elsevier Science Ltd. A ll rights reserved.