Rationale: Noncompliance with vaccination schedules undermines the potential benefits of immunization. The purpose of this study was to evaluate whether a reminder of the next vaccine dose sent by the Short Messaging Service (SMS) to the vaccinee's mobile phone increases compliance with hepatitis A + B and hepatitis A vaccination schedule.
Subjects and methods: In this experimental, controlled study, the study group comprised travelers who went to the Internacional-Clínic Vaccination Centre between the 1st June and 30th September of 2001 for the standard immunization schedule against hepatitis A + B and against hepatitis A. Trained health-care workers entered the data into a computer to generate text messages reminding vaccinees of their scheduled doses. Two control groups, one from the same period of the same year including travelers from the third office (Control 2001) and the second, all travelers seen in the same period of the previous year (Control 2000), were used.
Results: For the second hepatitis A + B dose, compliance in the study group (Message Groups) was 88.4% (83.3-92.2); in the Control 2001, 80.7% (76.3-84.4, relative risk [RR] 1.10 [1.02-1.17]); and in the Control 2000, 77.2% (73.3-80.5, RR 1.15 [1.07-1.22]). For the third hepatitis A + B vaccine dose, results were 47.1% (40.5-53.8); 26.9% (22.8-31.7, RR 1.75 [1.41-2.17]); and 23.6% (20.1-27.4, RR 2.00 [1.63-2.45]), respectively. As for the hepatitis A vaccine, compliance rates for the second dose were 27.7% (23.9-31.9); 16.4% (14.4-18.6, RR 1.69 [1.40-2.04]); and 13.2% (11.6-14.9, RR 2.10 [1.75-2.54]); respectively.
Conclusions: SMS seems to be an effective tool for increasing compliance with vaccination schedules.