Objective: To investigate the reasons for poor uptake of immunisation (non-immunisation) and the possible side effects of measles, mumps, and rubella vaccine in a catch up immunisation campaign during a community outbreak of measles.
Design: Descriptive study of reasons for non-immunisation and retrospective cohort study of side effects of the vaccine.
Setting: Secondary schools in South Glamorgan.
Subjects: Random cluster sample of the parents of 500 children targeted but not immunised and a randomised sample of 2866 of the children targeted.
Main outcome measures: Reasons for non-immunisation; symptoms among immunised and non-immunised children.
Results: Immunisation coverage of the campaign was only 43.4% (7633/17,595). The practical problems experienced included non-return of consent forms (6698/17,595), refusal of immunisation (2061/10,897 forms returned), and absence from school on day of immunisation (1203/8836 children with consent for immunisation). The most common reasons cited for non-immunisation were previous measles infection (145/232), previous immunisation against measles (78/232), and concern about side effects (55/232). Symptoms were equally common among immunised and non-immunised subjects. However, significantly more immunised boys than non-immunised boys reported fever (relative risk 2.31 (95% confidence interval 1.36 to 3.93)), rash (2.00 (1.10 to 3.64), joint symptoms (1.58; 1.05 to 2.38), and headache (1.31 (1.04 to 1.65)).
Conclusions: Many of the objections raised by parents could be overcome by emphasising that primary immunisation does not necessarily confer immunity and that diagnosis of measles is unreliable. Measles, mumps, and rubella vaccine is safe in children aged 11-15.