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Can Behaviourally-Informed Invitation Letters Increase Influenza Vaccination Rates?


Clinical trial shows that customized communications increases the rate of childhood immunization

Immunization is a global health and development success story, saving millions of lives every year. Vaccines reduce the risks of getting a disease by working with your body’s natural defenses to build protection. However, low vaccination rates in some areas are a cause of concern and many proposals have been put forward to increase these rates.

A clinical trial has explored the use of behaviourally-informed invitation letters and reminders as a potential technique for increasing influenza vaccination rates among children.

Childhood influenza is a common respiratory illness caused by the influenza virus. It is highly contagious and can lead to serious complications, such as pneumonia and bronchitis. In order to prevent the spread of influenza and protect children, vaccination is recommended.

Immunization is a key component of primary health care and an indisputable human right. It’s also one of the best health investments money can buy. Vaccines are also critical to the prevention and control of infectious disease outbreaks. Yet despite tremendous progress, vaccination coverage has plateaued in recent years and dropped since 2020.

In this clinical trial, researchers looked at whether behaviorally-informed invitation letters and reminders could increase the uptake of childhood influenza immunization through schools and GP practices.

The study involved two clinical trials. In the first trial, parents of eligible children in the intervention group registered at their local clinics and were sent the behaviourally-informed invitation letter by post. The control group children received the usual care. The letter was short in length, simplified, and made more salient by highlighting key points or actions required, thereby reducing the mental effort required to process the information and identify the action required. It was personalized with the name of the child and the parent, increasing the letter's personal relevance, and had a tear-off slip where individuals could note the time and date of their appointment, addressing implementation intentions.

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In the second trial, the parents were sent either behaviourally-informed letters or standard letters with and without reminders. Letters were sent to parents from providers, and reminders were sent to parents from the schools.

The results of the clinical trials showed that behaviorally-informed invitation letters and reminders were effective in increasing the uptake of childhood influenza immunization. In the school trial, the uptake of immunization was higher in the group that received the behaviorally-informed invitation letter along with a reminder compared to the group that received the standard invitation letter. In the GP practice trial, the immunization rate was 37.1% in the intervention group compared to 23.4% in the control group.

These findings indicate that behaviourally-informed letters were successful in increasing the immunization rates in children.

The results of this clinical study may have important implications for public health interventions aimed at increasing the uptake of childhood influenza immunization. By using behaviorally-informed invitation letters and reminders, healthcare providers can encourage parents to vaccinate their children more effectively.


The results of the clinical study suggest that behaviorally-informed invitation letters and reminders can increase the uptake of childhood influenza immunization through schools and GP practices. These findings have important implications for public health interventions aimed at increasing immunization rates and preventing the spread of infectious diseases. By taking a behaviorally-informed approach, healthcare providers can design more effective interventions that are tailored to the needs of the target population.
BMC Public Health, Jan-20-23
ClinicalTrials.gov NCT02921633, NCT02883972

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This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. CenTrial Data Ltd. does not take responsibility for possible health consequences of any person or persons reading or following the information in this educational content. Treatments and clinical trials mentioned may not be appropriate or available for all trial participants. Outcomes from treatments and clinical trials may vary from person to person. Consult with your doctor as to whether a clinical trial is a suitable option for your condition. Assistance from generative AI tools may have been used in writing this article.