Serological surveillance of influenza in Hamburg and Munich (1976/1977)

A monthly serological survey (HI-test) of influenza infections was done in Hamburg (1083 sera) and Munich (955 sera) between June 1976-February 1977 in order to find out if environment influences the host's response to infection. A higher frequency of seropositive reactions and percentage of protective antibodies (titer 1:40 and over) was found in the population of Hamburg versus Munich. The frequency was greater in individuals over 60 years (group IV) followed by persons 25-29 years (group III) than group II (15-24 years) and group I (0-14 years). There was no difference in the percentage of seropositive reactions within the 4 age groups from Munich. The GMT values of influenza antibodies in both populations studied followed the same pattern. Antibody titers against influenza antigens were found in decreasing order: A/Victoria 3/75, A/England 23/76, A/Port Chalmers 1/73, A/New Jersey 8/76, B/Hong Kong 8/73. The possible influence of climate on the host's response is discussed.