The goal of this randomized controlled trial is to learn if text message reminders sent through WhatsApp increase pneumococcal vaccination coverage in adults turning 65 years old in Chile. The main questions it aims to answer are:
Do text message reminders increase the proportion of adults aged 65 years who receive the pneumococcal vaccine compared to usual care? Do text message reminders increase pneumococcal vaccination coverage within the first 7 days after the message is sent? Is there an association between socioeconomic factors and pneumococcal vaccination coverage in adults aged 65 years in Chile?
Researchers will compare adults who receive a text message reminder to adults who receive no reminder (usual care) to see if the reminders increase vaccination uptake.
Participants will:
Be randomly assigned to receive a WhatsApp text message reminder about the pneumococcal vaccine or to receive no reminder Receive a second reminder on day 14 if they have not yet been vaccinated (intervention group only) Be followed for 6 weeks, with vaccination status checked at days 7, 21, and 42 from the start of the intervention
Adults born during the year 1961, turning 65 years of age in 2026
Resident in Chile at the time of the study
Valid mobile phone number registered in the National Immunization Registry (RNI)
Record of pneumococcal vaccination in the National Immunization Registry (RNI).
Identified as deceased in the Chilean Civil Registry and Identification Service.
Parallel
WhatsApp text message reminder for pneumococcal vaccination
BehavioralA text message reminder sent via WhatsApp on day 0 of the intervention by the Ministry of Health of Chile, through the official National Immunization Program contactability platform EMILIA (Rayén Salud). The message includes: (1) an official presentation identifying the Ministry of Health of Chile as the sender; (2) a reminder that the recipient is eligible for free pneumococcal vaccination upon turning 65 years of age; (3) confirmation that the 23-valent pneumococcal polysaccharide vaccine (PPV23) is guaranteed and available at no cost through the National Immunization Program; and (4) the name, address, and operating hours of vaccination centers in the participant's municipality of residence. A second reminder message with identical content will be sent on day 14 to participants in the intervention arm who have not yet received the vaccine. The message was developed by the National Immunization Program and the Ministry of Health Communications Unit, based on the Yale-UNICEF Vaccine M
Pneumococcal vaccination coverage at day 42
Proportion of randomized adults in each group who received the 23-valent pneumococcal polysaccharide vaccine (PPV23) within 42 days from the start of the intervention. Vaccination status will be ascertained through the National Immunization Registry (RNI). Coverage will be calculated as the number of vaccinated adults divided by the total number of randomized adults in each group. The association between the intervention and the outcome will be assessed using a chi-square test, and the magnitude of the association will be expressed as relative risk with 95% confidence intervals.
Pneumococcal vaccination coverage at day 7
Proportion of randomized adults in each group who received the 23-valent pneumococcal polysaccharide vaccine (PPV23) within 7 days from the start of the intervention. Vaccination status will be ascertained through the National Immunization Registry (RNI). Coverage will be calculated as the number of vaccinated adults divided by the total number of randomized adults in each group.
Pneumococcal vaccination coverage at day 21
Proportion of randomized adults in each group who received the 23-valent pneumococcal polysaccharide vaccine (PPV23) within 21 days from the start of the intervention. Vaccination status will be ascertained through the National Immunization Registry (RNI). Coverage will be calculated as the number of vaccinated adults divided by the total number of randomized adults in each group.
Time to pneumococcal vaccination
The time elapsed from randomization to administration of the 23-valent pneumococcal polysaccharide vaccine (PPV23) was analyzed using the Kaplan-Meier survival method. Time zero was defined as the date of message dispatch. Participants who had not been vaccinated by the end of the follow-up period were censored on day 42. Differences in survival curves between the intervention and control groups were assessed using the log-rank test.
Association between sociodemographic factors and pneumococcal vaccination coverage
Association between sociodemographic factors - specifically sex (male/female) and geographic region of residence (16 regions of Chile) - and pneumococcal vaccination coverage at day 42, estimated using a log-binomial regression model. Each factor will be analyzed independently. Results will be expressed as relative risk with 95% confidence intervals.
Click on the lead sponsor to view all of their trials.
Pablo Tomás Valenzuela García
Lead sponsor
Pontificia Universidad Catolica de Chile
Sponsor institution
Ministry of Health, Chile
Collaborator
This trial is not recruiting at the moment. You can still explore other options:
