Differential immune response to attenuated rubella virus vaccine

Serum samples collected from 18 volunteers 1, 2, and 3 months after vaccination with Cendehill strain of attenuated rubella virus vaccine were fractionated on a Sephadex G-200 column to test for immunoglobulin M (IgM) antibody. Seventeen of the 18 had demonstrable IgM antibody in serum collected 1 month postvaccination whereas only 5 and 3 had IgM antibody 2 and 3 months, respectively, post-inoculation. The geometric mean titers of hemagglutination-inhibiting antibody in the 19S fraction were 38, 7, and 6 at 1, 2, and 3 months after vaccination, whereas the corresponding 7S titers were 29, 53, and 57, respectively. Four other seronegative volunteers vaccinated with Cendevax were tested serially for total antibody only in whole blood obtained by finger pricks. Three of them showed appearance of antibody between 14 and 17 days and one between 17 and 21 days. It appears that vaccine-induced immune response is similar to natural infection especially with regard to the time of appearance of antibody and the relative proportions of IgM and IgG antibody thus produced.