What to do when rubella vaccine doesn't work
"An anxious patient trying to conceive says she's had two prior measles-mumps-rubella (MMR) vaccinations, as she tested negative for rubella immunity. A recent rubella IgG test was 'inconclusive,'" reports PETER LOMBARDI, MD, of Newmarket, ON. His question is: "Given the history of two previous documented MMR vaccinations, am I correct to say she doesn't need another vaccination and is considered immune, despite the inconclusive result?"
Over 97% of people given rubella vaccine form specific antibodies against it. It's recommended that patients who've been vaccinated previously but who aren't seropositive should have a second dose, although they're likely immune to natural infection. If your patient is healthy (immunocompetent) and the previous vaccines were stored and administered correctly, then she's probably immune and further vaccination is of little or no benefit. Her current risk of acquiring rubella is negligible, based on her likely immune status and the low rate of wild-type rubella infection in Canada, as a result of successful vaccination programs. KL