Specific IgG1 avidity maturation after rubella vaccination: a comparison with avidity maturation after primary infection with wild rubella virus.

Rubella reinfection, which can affect the developing foetus, is said to occur more frequently among people who have received rubella vaccine than among those whose rubella immunity is the result of a natural infection. We have compared the rate of increase in avidity of rubella-specific antibody in these two groups since differences either in the ability of the immune response to mature or in the rate at which it matures might be attributable to differences in antigen handling during the two modes of infection. Any differences in the type or the rate of maturation might then be responsible, at least in part, for the apparent increased susceptibility of vaccinees to reinfection. Although there was evidence to suggest that there was a slightly slower maturation rate at the later stages of the immune response among the vaccinees, the number of corresponding sera from cases of natural infection, taken several months after onset of symptoms, was insufficient to allow this to be demonstrated statistically. A larger, longitudinal study would be required to establish conclusively whether a true relationship between avidity maturation and an increase in reinfection rate among vaccinees exists.