Is MMR immunisation safe in chronic Idiopathic thrombocytopenic purpura?
- Dr M Erlewyn-Lajeunesse, Paediatric Allergy, Immunology & Infectious Diseases, Southampton University Hospital, Tremona Road, Southampton SO16 6YD, UK;
Idiopathic thrombocytopenic purpura (ITP) can occur after measles/mumps/rubella (MMR) immunisation, although its incidence is much lower than that after measles or rubella infection. MMR does not reactivate previous acute ITP.1 2 A second booster dose of MMR appears also to be safe in this regard.3 However, less is known about the safety of MMR in chronic ITP. We present three cases of children with chronic ITP whose illness was not exacerbated by immunisation (summarised in table 1).
In the first case, a girl was diagnosed at 13 months old after admission for a petechial rash with a platelet count of 5×109/l. Despite trials of prednisolone, pulsed dexamethasone and intravenous immunoglobulins, her disease remained refractory for 7 years, requiring annual hospital admissions. She experienced monthly exacerbations of petechiae associated with a platelet count <15×109/l. She received her first MMR vaccine at 4 years old while asymptomatic, with a platelet count of 63×109/l. She had no complications in the subsequent 6 weeks and she suffered only two flares of ITP in the following year. She received an MMR booster 2 years later, while asymptomatic, with a platelet count of 103×109/l. In the following year she experienced one relapse precipitated by a viral illness.
In the second case, a girl with pseudo-pseudo-hypoparathyroidism developed bruising and petechiae aged 12. Her platelet count was 6×109/l but improved to 52×109/l with conservative management. She was asymptomatic for 3 years, maintaining an average platelet count of 60×109/l before experiencing two symptomatic exacerbations, 2 years apart, which were both managed conservatively. She had initially received MMR vaccination without complication before the onset of ITP. She received an MMR booster 5 years after diagnosis and 6 months after her previous exacerbation. Her platelets were not checked at immunisation but had been 35×109/l 3 months previously and were 51×109/l 3 months later. She has remained asymptomatic since immunisation.
In the final case, a boy presented at 10 months old with a petechial rash and a platelet count of 11×109/l. In the 2 years since diagnosis, his platelet count has remained persistently below 20×109/l and he continues to suffer low-trauma bruising and a fluctuating rash. He received measles, mumps and rubella immunisation as separate single-antigen vaccines at his parents’ request. His platelet count was 19×109/l at vaccination and 8×109/l afterwards. His symptoms remain constant but stable.
This is the first report of the use of MMR in chronic ITP. From this small case series, we conclude that MMR immunisation is probably safe in children with chronic ITP, provided that their initial disease did not occur within 6 weeks of measles or rubella immunisation. MMR is relatively contraindicated in children with vaccine-related disease (within 6 weeks of immunisation), as two case reports suggest that they may be at higher risk of relapse.4 5 The British Committee for Standards in Haematology advises the measurement of measles titres in children with chronic ITP before boosting with MMR, to decide whether a further dose is indicated.6 If a child has not been previously immunised, then the risk–benefit of MMR should be weighed against the incidence of measles in the community at that time. The risk of ITP is much higher with wild-type measles and rubella, and, in the event of an outbreak, we would recommend that children with chronic ITP be immunised with MMR.