Just been on the phone to my sister in law, monaing about my DD1 catching chicken pox (sorry to mention it again). She told me that her boy (3 years old too) has just recovered from catching German Measles. I was surprised to hear this he had his MMR jab "on time" - are they still vulnerable to these diseases then until they have the follow on MMR at 4 years, have they misdiagnosed him or is his case rare? Just wondering if any of you know. Sorry if this seems a daft question, genuinely surprised by this one and it has got me wondering, can?t find any info about vulnerability between jabs on the internet anywhere..