The effect of measles infection and of vaccination with certain live vaccines upon humoral immunity to smallpox

The results of a study of the effect of measles infection and of vaccination with live measles vaccine (Leningrad-16 strain) on the level of humoral immunity to smallpox in children previously vaccinated against smallpox show that a measles infection markedly depressed the humoral immunity to smallpox, which did not reach its initial level in the 2-3 months of observation that followed clinical recovery. Immunoglobulin administered during the incubation period did not prevent the fall in smallpox antibody titres.It was also found that live measles vaccine, however intense the clinical reaction to the vaccination may be, does not have any marked effect on the smallpox antibody level in children. Similarly, 2 administrations of live trivalent poliomyelitis vaccine had no effect on humoral immunity to smallpox.