Text Message Reminders Increase Influenza Vaccination Rate

In a New York City-based study, text message reminders showed promise in boosting the rate of influenza vaccinations among low-income children and adolescents.

A series of text message reminders sent to parents led to modestly increased rates of influenza vaccination for children and adolescents in low-income, urban families, according to the results of a study published on April 25, 2012, in the Journal of the American Medical Association. The study was carried out by researchers at Columbia University in New York City during the 2010-2011 influenza season.

Influenza vaccination is particularly important for children and adolescents, who are at increased risk of influenza morbidity and mortality and are a significant source of influenza transmission to other high-risk populations. Nonetheless, national rates of influenza vaccination for children and adolescents are low, estimated at just 51% for those aged 6 months to 17 years during the 2010-2011 season. Coverage is generally lower among low-income populations, who are at greater risk of catching influenza because they live in crowded conditions.

Traditional vaccine reminders, such as mailings and phone calls, have had limited effect in low-income populations, yet the researchers hypothesized that text message reminders would be more successful. The researchers had previously shown success in increasing pediatric and adolescent vaccination rates using text reminders and, as they note, cell phone numbers tend to be more stable over time than home addresses or land lines.

The current study consisted of a randomized controlled trial of 9213 children and adolescents aged 6 months to 18 years who received care at 4 community-based clinics in New York City during the 2010-2011 influenza season and were assigned to either an intervention group or a usual care group. The study participants were primarily minorities, 88% were publicly insured, and 58% were from Spanish-speaking families.

Parents whose children were assigned to the intervention group received a series of weekly text messages. The first 3 messages included educational information on the seriousness of influenza infection and addressed vaccine misperceptions, and the next 2 provided information on influenza vaccine clinics scheduled on Saturdays between October 2010 and March 2011. Messages were discontinued after a child got the vaccine, and 2 additional messages were sent to parents of children who had not gotten the vaccine by January—1 informational, and 1 regarding clinic scheduling.

Participants in both the intervention and usual care groups received usual care, 1 automated phone reminder, and access to informational flyers posted at study sites. Of the 9213 participants, 1639 had received an influenza vaccination before the first text message was sent out and were excluded from the primary analysis.

The results showed that, as of March 31, 2011, 43.6% of children and adolescents in the intervention group had received an influenza vaccine, compared with 39.9% of those in the usual care group. In relative terms, those in the intervention group were 9% more likely to get the vaccine. At an earlier review date (November 30, December 15, or December 30, 2010, depending on age), 27.1% of those in the intervention group and 22.8% of those in the usual care group had received the influenza vaccine, meaning that those in the intervention group were 19% more likely to have been vaccinated.

After accounting for parents in the intervention group who did not receive the text messages for various reasons, 46.3% of those in the intervention group were vaccinated by March 31, 2011, compared with 39.9% of the usual care group, and 29.3% of those in the intervention group were vaccinated by the earlier review date, compared with 22.8% of the usual care group. The fact that the vaccination rate for the intervention group increased when those who definitely did not receive the text messages were excluded suggests that the messages had a motivating effect.

The authors of an editorial accompanying the study note that, although the raw increase in influenza vaccination rate for those in the intervention group was just under 4 percentage points, this would translate to an additional 2.5 million children and adolescents receiving the vaccination if extrapolated over the entire United States. “Modest steps are the norm when complex behaviors and systems are targeted such as receipt of preventive services,” they write. “There can be little doubt that in the next decade there will be an increasing use of such systems and their application to additional services.”

The editorial authors add that more study will be required to determine the optimal number and frequency of text message reminders and whether providing information about weekday vaccination options or offering recipients a number to call to immediately schedule a vaccination would have increased the response rate.