Few young children had mild reactions to the measles, mumps, and rubella vaccine and older children had nearly no vaccine related reactions
QUESTION: What are the adverse effects of the measles, mumps, and rubella (MMR) vaccine in children who are twins?
Randomised (unclear allocation concealment), blinded (nurses, investigators, and parents), placebo controlled, crossover trial.
A child health centre in Finland.
1162 children who were monozygous or heterozygous twins (581 twin pairs) between 14 months and 6 years of age with or without previous measles vaccination. Follow up was 100%.
For each twin pair, 1 child was allocated to receive a dose of vaccine first and then a dose of placebo, and the other child was allocated to receive a dose of placebo first and then a dose of vaccine given 3 weeks apart.
Main outcome measures
For 21 days, parents reported daily signs and symptoms including local reactions (redness with a diameter >1 inch, soreness, and swelling), rectal temperature, rhinorrhoea or cough, nausea or vomiting, diarrhoea, rash, …