Infections, vaccinations, and the risk of childhood leukaemia

A nationwide case-control study was conducted in New Zealand, to test hypot heses about the role of infections in the aetiology of childhood leukaemia. Children aged 0-14 years with leukaemia were matched on age and sex to con trols selected from birth records. Case ascertainment was virtually complet e and 121 (92%) of 131 eligible case families took part. The participation rate among the 303 first-choice eligible controls was 69%. Home interviews and serological tests were conducted. Adjusted relative risks were estimate d by logistic regression. There was an increased risk of leukaemia in relat ion to reported influenza infection of the child during the first year of l ife (adjusted odds ratio 6.8, 95% confidence interval 1.8-25.7). This could be a chance finding due to multiple comparisons, and it should be tested e lsewhere. Some key variables relevant to Greaves' hypothesis were not assoc iated with B-cell precursor acute lymphoblastic leukaemia (numbers of infec tions and vaccinations, firstborn status, attendance at preschool groups), although a smalt effect could not be ruled out with a study of this size. L eukaemia risk was higher among children in poorer social circumstances, and this was true for all eligible children as well as for the participants.