Smartphone-based active vaccine safety surveillance (SmartVax) at a Swiss adult vaccination clinic - a pilot study

Post-licensure surveillance of adverse events following immunisation (AEFI) is critical for detecting rare but severe AEFI. SmartVax software, using smartphone technology, actively solicits reports of AEFI via automated, opt-out SMS surveys to vaccine recipients in the days following immunisation. We report on a pilot study to test the feasibility and acceptance of SmartVax in Switzerland.

Between February and September 2020, consecutive subjects immunised at an adult immunisation clinic and the employee health service at the University Hospital of Basel were screened. Participants included three subgroups: healthcare workers (HCW), subjects with immune-mediated inflammatory diseases (IMID) and clients of the regular adult immunisation clinic. Three days after vaccination, participants received an SMS inquiring if they had any AEFI. In the case of an AEFI, subjects received an automated SMS with a link to an online survey assessing the type and temporal evolution of the AEFI. Descriptive statistics of response rate, time-to-response, frequency and type of AEFI by vaccine and clinical subgroup were performed.

Of 293 subjects screened, 276 were included (46.6% routine vaccination check-up visits, 33.3% HCW, 20.1% IMID patients) receiving 625 vaccinations during 360 immunisation visits. The SMS response rate was high (90.3%), with a median time-to-respond of 47 minutes (interquartile range11-205). After 29.8% of immunisation visits at least one AEFI was reported. There were no differences in frequency or type of AEFI between the three clinical subgroups. The recombinant, adjuvanted zoster vaccine Shingrix® was associated with the highest rate of local and systemic reactions.

Monitoring post-licensure vaccine safety using the active SMS-based surveillance system SmartVax is feasible in Switzerland. We observed a high acceptance in the diverse study population, including healthcare workers and IMID patients. High response rates in the elderly and reliable monitoring almost in real-time make SmartVax a promising tool for COVID-19 vaccine safety monitoring.