Across more than four million appointments, VaxCare’s SMS recall program improved vaccination rates at enrolled clinics by reminding patients they’re due and to talk to their provider about a flu shot.
Every flu season, patients come in for their annual physical, or for help managing blood pressure they can’t quite get under control. They’re due for a flu shot too, but that’s not why they came in, so it never comes up.
Throughout the 2025 flu season, we ran an SMS recall program across our primary-care network to see if we could increase the rate of flu vaccination. The result? Reaching out to patients before their visit led to a 19% relative increase in adult flu vaccinations. Simply reminding patients that they’re eligible is one of the most effective ways clinics may address dipping flu rates.
How the Program Works
VaxCare runs the reminders for enrolled clinics using the records they already keep, such as who’s due for a flu shot and who has a visit coming up.
Patients with a visit already booked get automated reminders in the days before, prompting them to get their flu shot while they’re there. Patients who are due but have nothing scheduled get a one-time message inviting them to come in.
Every message goes out from the practice’s own number, the one their patients recognize.
These pre-visit reminders carry most of the gain, and because they’re tied to a scheduled visit, they trigger automatically.
By the Numbers
Across our network, adults who received the reminders were vaccinated at 23.62%, versus 19.84% at clinics that weren’t running the program, a 19% relative increase. That’s roughly double what flu-reminder programs have reached before. A 2024 review of earlier trials put their average closer to a 9% increase.
A 19% relative increase in adult flu vaccination, across more than four million appointments.
One possible reason for the gap that isn’t captured in the trial literature: these messages came from the patient’s own practice. Patients are more likely to respond and act when they’re familiar with who’s messaging them.
And these aren’t one-season results. The relative gains held within rounding distance across the 2024 and 2025 seasons, even as the network grew.
High Volumes, High Returns
Broken out by practice volume, the strongest response came from the highest-volume practices, the large multi-site systems that see and vaccinate the most adults each season. In that group, adult flu vaccination rose about 36%, the program’s best result anywhere in the network.
That’s a high watermark, but for a health system, the rate is one of several factors, including scale and investment. At the network average, simply sending automated text reminders to 100,000 adults would lead to several thousand additional flu shots, with no added phone calls or staff time. The reminders run off appointments already on the books, so no additional lift is needed, regardless of how many patients are in the network.
Adults 65 and older reached the highest vaccination rate overall at about one in three. They start from a higher base, so the increase off that number was smaller, but the reminders still put them at the top rate of any age group.
Adults 50 to 64 saw the biggest relative increase at 23.7%. Their flu coverage has trailed for years, even though the shot is squarely recommended for them. These are working adults who come in when something needs attention, and reminders help to keep seasonal vaccination top-of-mind.
Adults 18 to 26 saw a 19.1% increase. Young adults are often written off as indifferent to the flu shot, but with a message from the care provider at their own medical home, their response came in close to the network average.
And the results hold for VaxCare’s pediatric program, Vax-to-School, which has already been published in a peer-reviewed journal (Clarke et al., BMC Digital Health, 2025). There, the largest gains came from adolescents, the age group standard outreach gets through to least. Different studies, different age groups, but the same finding: text-based recall reaches the patients other channels miss.
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New Flu Season, Same Patients
Left alone, the same patients slip past season after season, and the shots that could have protected them never happen. A well-timed reminder changes that. Last season it raised adult flu vaccination 19% across our network.
The reminders run off existing appointments, are sent on their own, and honor opt-outs automatically. Once clinics enroll, whether individually or as an entire system, the real change is in who they’re able to reach. Now the adults who were always eligible can finally hear from their own practice in time to act.
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