An increase in idiopathic thrombocytopenic purpura (ITP) cases in the 6 weeks following the first dose of the measles, mumps and rubella (MMR) vaccine has been established, with absolute risks estimated as 1 in 22,300 (1) and 1 in 21,000 vaccine doses (2), and two in every three cases being vaccine-attributable.
However, the risk after a second dose of MMR vaccine has not been investigated.
- idiopathic thrombocytopenic purpura
- measles, mumps and rubella
- vaccine safety