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Text messaging reminders for influenza vaccine in primary care: a cluster randomised controlled trial (TXT4FLUJAB)
  1. Emily Herrett1,
  2. Elizabeth Williamson1,
  3. Tjeerd van Staa2,3,
  4. Michael Ranopa1,
  5. Caroline Free1,
  6. Tim Chadborn4,
  7. Ben Goldacre1,5,
  8. Liam Smeeth1
  1. 1London School of Hygiene and Tropical Medicine, London, UK
  2. 2Health eResearch Centre, Farr Institute, University of Manchester, Manchester, UK
  3. 3Faculty of Sciences, Division of Pharmacoepidemiology and Clinical Pharmacology, Department of Pharmaceutical Sciences, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
  4. 4Health and Wellbeing Directorate, Public health England, Wellington House, London, UK
  5. 5Department of Primary Care Health Sciences, Centre for Evidence Based Medicine, University of Oxford, Radcliffe Observatory Quarter, Oxford, UK
  1. Correspondence to Dr Emily Herrett; emily.herrett{at}


Objectives (1) To develop methods for conducting cluster randomised trials of text messaging interventions utilising routine electronic health records at low cost; (2) to assess the effectiveness of text messaging influenza vaccine reminders in increasing vaccine uptake in patients with chronic conditions.

Design Cluster randomised trial with general practices as clusters.

Setting English primary care.

Participants 156 general practices, who used text messaging software, who had not previously used text message influenza vaccination reminders. Eligible patients were aged 18–64 in ‘at-risk’ groups.

Interventions Practices were randomly allocated to either an intervention or standard care arm in the 2013 influenza season (September to December). Practices in the intervention arm were asked to send a text message influenza vaccination reminder to their at-risk patients under 65. Practices in the standard care arm were asked to continue their influenza campaign as planned.

Blinding Practices were not blinded. Analysis was performed blinded to practice allocation.

Main outcome measures Practice-level influenza vaccine uptake among at-risk patients aged 18–64 years.

Results 77 practices were randomised to the intervention group (76 analysed, n at-risk patients=51 121), 79 to the standard care group (79 analysed, n at-risk patients=51 136). The text message increased absolute vaccine uptake by 2.62% (95% CI −0.09% to 5.33%), p=0.058, though this could have been due to chance. Within intervention clusters, a median 21.0% (IQR 10.2% to 47.0%) of eligible patients were sent a text message. The number needed to treat was 7.0 (95% CI −0.29 to 14.3).

Conclusions Patient follow-up using routine electronic health records is a low cost method of conducting cluster randomised trials. Text messaging reminders are likely to result in modest improvements in influenza vaccine uptake, but levels of patients being texted need to markedly increase if text messaging reminders are to have much effect.

Trial registration number ISRCTN48840025.


This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See:

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