The data comprise ages in days at oral polio vaccine (OPV) and first hospital admission for intussusception in children between the ages of 27 and 365 days. There are 207 cases.
opvdatA data frame containing 207 rows and 8 columns. The column names are 'case' (individual identifier), 'sta' (age on first day of the observation period), 'end' (age on last day of the observation period), 'intus' (age at admission for intussusception), 'opv' (age at first dose of OPV), 'opvd2' (age at second dose of OPV), 'opvd3' (age at third dose of OPV), 'sex' (1 for males, 2 for females).
Andrews N., Miller, E., Waight, P., Farrington, P., Crowcroft, N., Stowe, J., and Taylor B. (2002). Does oral polio vaccine cause intussusception in infants? Evidence from a sequence of three self-controlled case series studies in the United Kingdom. European Journal of Epidemiology 17, 701--706.