Rubella antibodies in women of childbearing age during an epidemic and the two years thereafter.

An epidemic of rubella started in the south of Israel late in 1971, and reached the north of the country in the spring of 1972. Between April 1972 and April 1975, 14,149 women of childbearing age from Haifa and the north of Israel were examined for rubella antibodies by hemagglutination inhibition (HI) and complement fixation (CF) tests. During the year of the epidemic, CF antibody titers of greater than or equal 16 were found in 9.3% of cases with HI antibody titers of 64, in 37.7% of cases with HI titers of 128, and in 71.7% of cases with HI titers of greater than or equal 256. Two years later there were no women with CF antibody titers of greater than or equal 16 among those with HI titers of 64, and the percentage with CF antibody titers of greater than or equal 16 had decreased to 4.3% among women with HI titers of 128 and to 38.7% among those with HI antibody titers of greater than or equal 256. These results show that the determination of CF antibody titers may be useful in the serodiagnosis of recent rubella infection, especially diring an epidemic occurring several years after a previous one. The epidemic hardly altered the percentage of women susceptible to rubella. Although vaccination of 12-year-old girs was introduced in Israel in 1972, careful surveillance of women of childbearing age still remains necessary for detection and vaccination of susceptible nonpregnant women.